Managing water for waders

blog L sittingYour task, should you choose to accept it, is to turn farmland into a haven for breeding waders. The only tools you have at your disposal are tractors and cows and we will give you permission to pump water out of nearby rivers when conditions allow. That’s how it started. These days the diggers look big enough to use on a motorway construction site!

If your aim is to maximise the number of pairs of breeding waders on your lowland wet grassland farm or nature reserve, then one of the key issues is to get the water levels right. This blog focuses on providing an appropriate mix of ditches, pools and grassland for species such as Lapwing, Redshank and Snipe and then keeping everything wet enough (but not too wet) during the important chick-rearing season.

This blog is not just about maximising the number of breeding waders on a nature reserve. It’s also about working with neighbouring farmers, in order to secure fresh water supplies for the future and to reduce the risk of salt-water inundations, associated with sea level rise. In the long-term, stakeholder engagement has proved far more important than habitat management, as you will read below.

Understanding water levels

When developing lowland wet grasslands for waders, an extra five cm of late-winter rain can make a huge difference, especially if you can capture as much as possible of the rain that falls or can draw water from a swollen river. Mark Smart, the Senior Site Manager for the RSPB’s Berney Marshes and Breydon Water reserve in East Anglia, understands grazing marshes and how to capture and distribute water, in order to provide the muddy edges where wader chicks find insects. An aerial photograph of Berney Marsh shows how Mark has designed a special landscape to capture winter rain – one that is ideal for Lapwings and other waders.

Mark has taken the lessons he has learnt on RSPB nature reserves and shared them widely, a contribution to conservation that earned him one of the 2018 Marsh Awards for Wetland Conservation from the Wildfowl & Wetland Trust.

From wheat and barley to ducks and waders

blog cow eatingThe marshes of the Norfolk Broads have been drying out for 2000 years. By the 1970s, and after over 400 years of farming, the Halvergate Marsh complex was on the point of being fully drained and by 1985 much of the wet grassland in which waders formerly bred had already been lost and turned into arable fields. At this point, the RSPB made its first purchase of land, as they tried to retain at least some of the threatened habitat which is so important to winter wildfowl and summer waders. At the same time, campaigning by local and national conservationists secured legal protection for the unique Broadland scenery and the species that rely upon the habitats it contains, thereby halting the advance of the combine harvesters.

The importance of Halvergate Marshes for wildlife has long been known, and in 1987 it became the site of the UKs first Environmentally Sensitive Area – the prototype for subsequent agri-environment schemes. Lowland wet grasslands are traditionally drained using ‘footdrains’ – narrow, shallow channels that connect low-lying parts of the fields with surrounding ditches, in order to drain them.

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The muddy edges of a footdrain

These same footdrains can be used to hold and manage surface water levels within fields, by blocking the ditch connections with sluices. In the 1990s, Mark pioneered the design and deployment of footdrains on lowland wet grasslands, and the kit needed for their construction. Through his skills, enthusiasm and collaborations with grassland managers throughout lowland England, footdrains and the water that they can contain are now a common sight. Many generations of wader families have enjoyed the invertebrate food that footdrains support.

The breeding season for waders is very short – with the first Lapwing claiming territories in March and most chicks fledged by the end of July. Outside these months, these wet grasslands provide excellent grazing for geese and ducks in the winter and cattle in the summer. The task of nature reserve managers is to work with graziers to try to ensure that cattle deliver appropriate sward heights for winter wildfowl and summer waders.

Not just water

fence 2By creating a hot-spot for nesting birds, within an intensively-farmed landscape, land-managers also produce a food-rich area for predators, attracted in by concentrations of eggs, chicks and sitting adults. Restricting the activities of species such as foxes and crows is an important part of the role of an RSPB warden, carried out through site management and active control measures. By focusing these activities in the winter period, the RSPB’s Halvergate Marshes team are able to stop corvids and foxes from setting up territories within the area that is managed for breeding waders. Electric fencing can help to prevent foxes moving onto the site in spring, while changing the way that core wader areas are managed helps to reduce fox/nest interactions by, for instance:

  • Adding shallow ditches in the right places can break up the site into compartments and reduce the likelihood that nests will be predated.
  • Leaving areas with long grass, that is good for small mammals and the mustelids and foxes that prey upon them, can change the focus of hunting activities.
  • Erecting temporary fencing, during at least the early part of the nesting season, can both provide protection and potentially increase the synchronicity of nesting attempts and hence the ability of birds effectively to mob predators.

blog L chickThere is more about these measures in these blogs, with links to papers from the RSPB and University of East Anglia team of conservation researchers:

There is annual management of the Berney site too, with foot-drains to be re-cut, spoil to be spread in ways that can provide a mix of water-levels and more muddy edges, and rotovation of some areas to increase the diversity of habitats. These techniques might seem rather different to the ones that are used by farmers but many of the other operations at Berney are the same as would be seen outside nature reserves, with fences to mend, stock to manage and creeping thistle and rush to ‘weed-wipe’.

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Rotovation, carried out in dry conditions, adds heterogeneity and creates bare, muddy areas

Measuring success

The development of Berney Marshes has been hugely successful. Back in 1987, there were only 13 pairs of wader breeding on the site – nine pairs of Redshank and four of Lapwing. The total for 2019 looks like being about 270 pairs – over twenty times as many.

blog RK graphRedshank: The graph alongside illustrates how Redshank numbers have changed across the decades. At the same time as Breeding Bird Survey (BTO, JNCC & RSPB) for England results revealed huge declines, with a loss of nearly half in the period 1995-2017, Redshank pairs on Berney Marshes have been increasing. Even on this site, there is a suggestion that the peak number of pairs may be in the past. Given the pressures on breeding Redshank on saltmarsh habitats (blog: Redshank – the ‘warden of the marshes’), providing breeding habitat in coastal marshes, inside sea-walls, may be particularly important. Hopefully, the latest earthworks (see later) will create more space for Redshank.

Left image below shows Redshank nest in a clump of grass. The right image shows a Lapwing nest in a newly-rotovated patch. 

 

blog L graphLapwing: Between 1988 and 1998, the number of pairs of Lapwing rose from 14 to 79, reaching a peak of 157 in 2010. Numbers vary, according to spring weather and water levels, with between 83 and 130 pairs in the years 2011 to 2019. The national decline in England was 28% between 1995 and 2017 (Breeding Bird Survey) – not quite as drastic as for Redshank but still worrying. Intensive studies at Berney have shown that productivity is only high enough to boost numbers in some years. The latest project by UEA and RSPB conservation scientists involves trialling temporary electric fences to provide protection for first clutches and broods. Hopefully Berney can become a net exporter of Lapwings in most years.

Oystercatcher: There were no Oystercatchers breeding at Berney back in 1997. The peak number of pairs was 18 in 2009, with an average of ten pairs in subsequent years. Nationally, numbers in England have increased but with major declines in Scotland, which is the species’ heartland within the UK. This is discussed in an earlier WaderTales blog.

Avocet: The RSPB’s logo species has been hugely successful, nationally, with the help of protection and habitat creation. The first pair of Avocets bred at Berney in 1992 and pairs have bred in most years since then, with over thirty pairs in nine years but no pairs in 2013 or 2014. The 2019 count is 35 pairs and there is potential for further growth in numbers across the site, with the creation of more island homes (see below).

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Combined harvesters have been replaced by nesting Avocets

Snipe: Despite all of the excellent habitat creation work, there have never been more than 8 pairs of Snipe recorded on Berney and only between 0 and 3 pairs in each of the last ten years. The underlying soils at Berney are clay-based, which may not suit this species.

Sharing the knowledge

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Redshank chick: science is an important feature of the work at Berney

Although it’s great that the RSPB has been able to buy and develop land for breeding waders in the Yare Valley, the impact of their work has been far larger, thanks to management agreements with other landowners. Mark Smart and the RSPB have set up Broads Land Management Services, to deliver wet grasslands that attract the top tier of conservation payments for farmers working in the Broads. Much of the recent work has been part of the Water Mills and Marshes Project, funded by HLF and led by the Broads Authority. Using specialist ditch-cutting and spoil-spreading equipment, the team has been able to create wet features within top-quality grazing fields. This is not just a local initiative; the kit and the advice have had impacts on farms and nature reserves across the country.

For his work for wetland conservation, Mark Smart received a Marsh Award for Wetland Conservation from the Wildfowl & Wetland Trust in 2018. “Mark Smart received his award for his 17 years managing RSPB Berney Marshes in the Norfolk Broads. Over this period, he brought together landowners, conservationists, local authorities and scientists to improve the marshes for wildlife. Today more than 300 pairs of wading birds nest there each spring, and more than 100,000 waterbirds return to it each winter.”

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Illustrations above shows work that has been completed at Somerleyton in Suffolk and a newly-fledged Lapwing.

blog DutchWorking with his wife, Jen Smart, who is a Principal Conservation Scientist at the RSPB’s centre for Conservation, Mark has added a Dutch dimension to the RSPB’s advice work by co-authoring Meadowbirds on the horizon of southwest Friesland.  This report has just been published by the International Wader Study Group.

Climate – ‘the new normal’

Fresh water is an increasingly important commodity in East Anglia – for farmers and for nature reserve wardens, looking to maximise agricultural and wader chick production. More extreme weather patterns are already producing periods of drought and intense periods of rain, while a rising sea-level is increasing the salinity of rivers and limiting extraction opportunities. Broadland farmers are looking for a reliable water supply, the Environment Agency is looking for ways to reinforce sea defences and for places to store fresh water, in order to avoid flooding, and the RSPB wants to hold more water in the late winter that can be used to keep areas wet in the early summer. With some lateral thinking, many of the needs of these key stakeholders can be met in partnership projects, as shown below

The Environment Agency’s need for material to raise sea defences provided Mark Smart with an opportunity to provide more pools and scrapes for breeding waders. It was a win-win solution; free habitat creation work for the RSPB and minimal movement of the clay and top-soil that the Environment Agency needed. In the images below, you can see this work in progress and the islands that are now being used by nesting Avocets.

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The most recent project is an ambitious water storage and flood reduction scheme for the whole of Halvergate Marsh. This will keep salt water out of these important grazing marshes and store fresh water for summer use. The £2 million Halvergate Marshes Water Level Management Improvement Scheme is a joint initiative, funded by DEFRA and delivered by the Water Management Alliance. The project involves a large number of stakeholders, including the Broads Internal Drainage Board, RSPB and neighbouring farming estates.

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The Water Level Management Improvement Scheme is a huge undertaking, with 8 km of new ditches, 240 piped culverts and 12 big sluices, that will create storage for 60,000 cubic metres of fresh water and systems to distribute this water over the course of a dry East Anglian summer. One of the most impressive features of the project, illustrating the imagination of the design team, is the Higher Level Carrier, a ‘flyover’ ditch system that passes over the top of existing wet grazing land to get water to some of the driest part of Halvergate Marshes (left picture below). This high-level water transportation route was constructed using locally-sourced clay, thereby creating shallow pools around which yet more waders are already nesting.

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When designing this project, the opportunity was taken to develop opportunities for birdwatchers to see the birds that will be drawn into the wettest areas, by making sure that the ‘best bits’ are close to public access points on the Weavers’ Way, the 61 mile (100 km) long-distance path running from Cromer to Great Yarmouth.

Aspirations

Mark Smart has not finished yet! Plans are afoot to develop the RSPB’s land that is closest to Great Yarmouth, recently purchased using a WREN grant. If agreed, this can provide an alternative, safe high-tide refuge area for tens of thousands of waders and wildfowl that roost on the mud and saltmarsh at the mouth of the Yare. Their current high-tide refuge is threatened by sea-level rise and developments proposed for the outskirts of Great Yarmouth.

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This proposed roosting area will be part of an extension to the Halvergate Marshes Water Level Management Improvement Scheme, which will add another 10,000 cubic metres of water storage. Alongside flood alleviation and fresh-water conservation, this scheme will create fifty hectares of additional shallow wader and waterfowl scrapes adjacent to Breydon Water.

blog Wood spThe new scrapes should not only attract wintering and breeding birds but also many passage waders, such as the Wood Sandpiper pictured to the right. The whole scheme has the potential to be another win-win-win-win, for the owners of low-lying properties, for Broadland farmers, for internationally important bird populations and for local and visiting birdwatchers.

Read more

Information about the RSPB’s Berney Marshes & Breydon Water reserve can be found on the RSPB’s website. Click here

There is information about the Water, Mills and Marshes project here.

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GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

 

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Chicks and ticks

How do ticks affect Golden Plover chicks? pic chick on moveBy utilising data from an existing study, David Douglas and James Pearce-Higgins have discovered that Golden Plover chicks that carry more sheep-ticks Ixodes ricinus have a lower chance of survival. Their findings are written up as a paper in Bird Study. The work is only based on a small sample and the data don’t identify the mechanism that leads to increased mortality but, given the current interest in the biological effects of ticks, the findings are interesting.

Costs of carrying ticks

Carrying ticks has three potential effects on wader chicks

  • Ticks suck blood, which could be costly.
  • Ticks can introduce diseases, via tick-borne bacteria and viruses.
  • There may be effects on feeding efficiency, via impaired vision, hearing etc.

Sheep ticks act as vectors for a variety of pathogens, including the louping ill virus (LIV) which can affect a range of domestic and wild mammals, as well as wild birds. LIV is known to cause high mortality of Red Grouse chicks but there has been no previous assessment of the effects of sheep ticks on other moorland birds, such as breeding waders. It should be noted that wader chicks eat ticks – so they are not ‘all bad’.

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Ticks can clearly be seen on the unfeathered lower eyelid of this young chick. There are smaller ticks attached to the gape at the base of the beak as well.

All sorts of things could influence the probability of tick infestation in birds:

  • Ticks may be able to survive better in warmer conditions.
  • Tick numbers can be affected by the number of mammalian hosts.
  • Mammal to bird transfer could be affected by land management and habitat structure.

Ecological interactions between ectoparasitic ticks and waders are not well understood. Given possible increases in tick abundance with climate change, the authors of the new study felt that it would be useful to test whether ticks have detectable effects on the Golden Plover chicks that carry them.

Spotting an opportunity

The Golden Plover chicks that provided the data used in this paper were caught as part of a wind farm study at Gordonbush in northern Scotland, a site made up of 33 km2 of blanket bog. There is more information about the study in these two papers:

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Gordonbush, prior to the development of a wind farm

Tick numbers on Golden Plover chicks were collected at the time of ringing (within 24 hours of hatching) and during subsequent recaptures. Recapture was facilitated by locating tagged birds using radio-location. On each capture, chicks were weighed and the number of ticks visible on the bare parts of the head (around the eyes and bill) were counted. Most ticks attach themselves to the bare parts of the head and neck.

Variation in tick loads on Golden Plover chicks

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Incubating adult. Golden Plovers commence primary moult at the start of (or before) incubation. Read more here.

The number of sheep-ticks found on these Golden Plover chicks was higher than those previously reported for waders but were within the range of those found on Red Grouse on moorland. Previous wader studies had been focused upon areas with sheep, which were routinely treated to reduce tick infestations. In the current study it was found that:

  • 90% of chicks were carrying ticks, with between 1 and 12 ticks being found on each affected Golden Plover chick. The highest tick-load was found in mid-age chicks.
  • Tick loads were higher during periods with warmer maximum temperatures and when chicks were estimated to have moved through taller vegetation between recaptures.
  • Chick growth rates were depressed by high tick-loads, especially when temperatures were warmer.
  • Of the 21 chicks, 4 fledged, 13 died and the outcomes for the other 4 were unknown. Half of the deaths appeared to have been due to predation and half to starvation/exposure.
  • Chicks that were heavier (for their ages) were more likely to survive. Those with higher tick loads (for their ages) were less likely to survive.

With the small sample size, it was not possible to detect a correlation between tick load and chick growth rates but low survival was correlated with high tick-loads. This had not previously been documented for waders.

Implications for wader conservation

pic red deerGordonbush is an area where there is no grazing by domestic animals so the likely mammalian tick-hosts are Red Deer in particular and also Mountain Hare. The correlation between warmer weather and tick numbers, found in this study, could be explained by increased tick activity, while the link to taller vegetation may well be explained by ticks seeking damper microhabitats. In their discussion of the results, the authors suggest potential ways that ticks and waders, of different ages, might interact. Anyone looking to expand the work, in order to understand the mechanics of tick infestation, is likely to spend more time looking at ticks than waders!

pic Curlew

Could ticks be reducing survival probabilities for  young Curlew?

The authors of this paper were not able to test for the presence of disease (such as LIV) in their Golden Plover population but this is a plausible cause of the increased probability of mortality. In a study in Yorkshire by Newborn et al. (2009), no evidence was found of LIV in wader chicks, whereas it was present in 3.6% of a sample of Red Grouse chicks at the same sites. Newborn and colleagues report that a single Eurasian Curlew chick has previously been recorded to be seropositive for LIV. In the Newborn study, the lowest incidence of ticks among waders was in Lapwings (6% of broods), followed by Golden Plover (47% of broods had ticks) and Curlew (91% of broods). There is a hint, in these data, that ticks might more commonly attach themselves to wader chicks that are found in taller vegetation.

Despite high tick loads on chicks, and the correlation with lower chick survival, the overall percentage of Golden Plover chicks known to fledge in the Gordonbush study (19%) is comparable with other studies. Perhaps ticks are only causing the deaths of chicks that would have died anyway?

pic Red GrouseThe authors suggest that no case should be made for tick-control, to help breeding waders, until it is clear whether tick-based chick mortality limits Golden Plover and other wader populations on moorland. In the paper, they argue that previous attempts to reduce moorland tick abundance and tick loads on Red Grouse have failed to detect convincing evidence of improvements in grouse survival, breeding success or post-breeding densities.

A range of methods have been deployed in attempts to reduce moorland tick abundance and tick loads on Red Grouse, including reducing densities of mammalian tick hosts (Mountain Hare and deer) and deploying acaricides (as used in sheep dips). See this link to material from GWCT on ticks and Red Grouse.

In conclusion

pic older chickWork at a single site over two years appears to have documented a level of tick infestation in Golden Plovers that is associated with chick mortality. It is not clear how chicks are being affected, particularly given that there is insufficient evidence thus far that ticks affect chick growth rate.

The authors collected the data analysed in this paper for other studies – the focus was not on tick effects – and they hope that funding might be found for future research focusing upon the associations between ticks and waders, other birds and other animals. Until that happens, it would be useful if shorebird biologists who repeatedly handle wader chicks, in order to measure growth and survival rates, could routinely record the presence or absence of ticks.

Given that warming temperatures could lead to increased tick abundance, this seems to be a good time to discover more about tick behaviour, the importance of ticks as a food source for wader chicks and whether tick-loads are reducing growth rates and fledging success in other wader species.

Paper

This research is published in the BTO journal Bird Study. Click on the details below to link to the full paper:

Variation in ectoparasitic sheep tick Ixodes ricinus infestation on European Golden Plover chicks Pluvialis apricaria and implications for growth and survival. David J. T. Douglas and James W. Pearce-Higgins. Bird Study. June 2019.

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GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

Redshank – the ‘warden of the marshes’

blog nesting RKAre subsidies that are designed to protect the biodiversity of Britain’s saltmarshes, delivering the planned, conservation benefits? In particular, is this investment supporting populations of amber-listed Redshank?

About 25,000 pairs of Redshank are thought to breed in the United Kingdom (link to APEP), with about half of these nesting in coastal saltmarshes. In recognition of the importance of saltmarshes, agricultural grants are available to support their management, with a focus on providing an appropriate level of grazing for a range of plants, birds and insects. In their 2019 paper in the Journal of Applied Ecology, Lucy Mason and her RSPB colleagues ask some serious questions – are these agricultural subsidies being well spent?

Saltmarsh grazing is an important conservation prescription that is used to try to boost, or at least maintain, populations of breeding waders, particularly Redshank, as well as to conserve the unique herb-rich habitats in which they hide their nests and raise their young. This study follows on from an earlier paper that showed that more than 50% of saltmarsh-nesting Redshank in Great Britain were lost between 1985 and 2011, and three papers by Elwyn Sharps on the impacts of cattle that graze saltmarshes during the Redshank breeding season (about which there is more below).

Why worry about Redshank?

The latest population estimate for Redshank in the United Kingdom is 25,000 pairs, as many as 50% of which are birds nesting on saltings. Redshank is an amber-listed species of conservation concern in the UK, with the most recent population changes showing a drop of 44% between 1995 and 2017 (Breeding Bird Survey) and a larger decline over the period since 1990.

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What are saltmarshes?

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Rich plant communities

Saltmarshes are intricate, dynamic habitats, where land meets sea. They are highly productive ecosystems, rich in plants, birds and insects. Traditionally, they would have been grazed by herbivorous mammals and waterfowl but, in the absence of free-roaming animals, the only way to maintain the short but diverse swards favoured by specialist plants and animals is to employ the services of cattle and sheep. Although saltmarsh still covers large areas, it is estimated that over 50% has been lost or degraded globally, thanks to reclamation and erosion. Further losses are occurring, as saltmarshes get squeezed between rising sea levels and the hard sea defences that protect coastal settlements and farmland.

The structure of saltmarsh is created by the way that water moves, as waves dissipate their energy and deposit silt during higher, spring and storm tides and the water then runs back off the salting. The latter process creates branching creeks that drain the marsh, from small meandering ditches, that are just big enough to catch a foot and twist an ankle, to waist-deep, fast-flowing channels with slippery, muddy sides.

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Deep creeks of outer marsh

Anyone who has been out on a marsh will know that, with some local knowledge, it is possible to make your way from the sea-wall to the edge of the saltmarsh along a route that lies between two creek systems. On the other hand, travelling along the muddy, salting edge parallel to the sea-wall is difficult, as it involves crossing creeks. Grazing animals face the same navigation problems; it’s a lot easier to graze wide expanses of the upper marsh than the outer areas that are dissected by deep creeks. As discussed below, these upper areas, with a mixture of short grass and clumps of longer grass, are also the ones that are favoured by breeding Redshank.

How many Redshank breed on saltmarshes?

A 2013 paper by Lucy Malpas (now Lucy Mason) in Bird Study brought together evidence of declines in saltmarsh-breeding Redshank over a 26-year period. An estimated total of 21,431 pairs were found to be breeding on British saltmarsh in 1985 but this had dropped to 11,946 pairs in 2011, with the highest proportion of the remaining population found in East Anglia. The 2011 survey showed that there were regional variations (see table), with the biggest declines in Scotland. Looking at the way that saltmarshes were managed, Lucy found that Redshank declines were less severe on conservation-managed sites in East Anglia and the South of England, where grazing pressures remained low, but more severe on conservation-managed sites in the North West, where heavy grazing persisted.

tableAt the end of this Bird Study paper, Lucy and her colleagues suggest that saltmarsh-breeding Redshank declines are likely to be driven by a lack of suitable nesting habitat. Conservation management schemes and site protection, implemented since 1996, appeared not to be delivering the grazing regimes and associated habitat conditions required by this species, particularly in the northwest of England. Although habitat changes may not be linked to unsuitable grazing management in all regions, they suggested the need for a better understanding of grazing practices and consideration of potential long-term management solutions.

Grazing levels and Redshank numbers

Intensive grazing leads to a very short uniform sward, lighter grazing produces a more uneven patchy sward with diverse heights, whilst no grazing can leave saltmarshes with dense communities of coarse grasses. For Redshank, that need clumps of grass in which to hide their nests and more open areas in which chicks can feed, light grazing is a key management tool.  Elwyn Sharps and colleagues, working on the salt marshes of the Ribble Estuary in northwest England, were interested to see how grazing regimes worked for the local Redshanks. Elwyn showed that the risk of Redshank nest predation increased from 28% with no breeding-season grazing to 95% with grazing of 0.5 cattle per hectare per year, which is still within the definition of light grazing.

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In follow-up work, Elwyn showed that livestock play an important role in creating the clumps of Festuca rubra habitat preferred by Redshank nesting on the Ribble Estuary but that even low-intensity conservation grazing can create a shorter than ideal sward height, potentially leaving Redshank nests more vulnerable to predators. There is more about this in the WaderTales blog: Big Foot and the Redshank Nest.

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Grazing the higher saltmarsh

One of the missing elements from Elwyn’s first two papers about grazing levels was an understanding of the behaviour of cattle on saltmarsh. In the next piece of work, Elwyn and colleagues tracked the movements of individual cattle, using GPS collars, and assessed the vulnerability of nesting Redshank, using dummy nests. In a 2017 paper in Ecology & Evolution, they showed that cattle spend their time in the same areas of saltmarsh as the ones in which Redshanks like to nest. Their conclusion is that “grazing management should aim to keep livestock away from Redshank nesting habitat between mid-April and mid-July, when nests are active, through delaying the onset of grazing or introducing a rotational grazing system”.

Do conservation payments deliver?

To assess whether conservation grazing is being achieved, and whether agri-environment schemes are effective in delivering this management, Lucy Mason and her colleagues conducted a national survey of English saltmarshes, scoring the management on each site as optimal, suboptimal or detrimental, based on five aspects of grazing (presence, stock type, intensity, timing and habitat impact). They surveyed 213 saltmarsh sites in three regions during 2013, representing 50% of the vegetated saltmarsh in England. Of the study sites, 114 (54%) received payments for saltmarsh management and/or conservation grazing options through Higher Level Stewardship, or the Countryside Stewardship Scheme. The annual cost of saltmarsh and grazing management options in the marshes that were studied was £543,075 for 10,218 ha of saltmarsh, equating to over £5 million spent on saltmarsh management options over the course of 10 years.

blog muddy creekTo assess grazing levels, the team visited each site up to four times during the core grazing period (April–October), to count cattle. They also assessed the longer-term impact of grazing on saltmarsh habitat, by measuring sward height and heterogeneity. Combining the measurements of site condition and analysing the results produced the following key findings:

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    Nest hidden in clump of grass

    Although most saltmarsh sites in England that are capable of supporting grazing are grazed by livestock, conservation grazing is not being achieved.

  • Nationally, the biggest management failings relate to the timing of grazing and the way that grazing impacts upon habitat structure.
  • There were regional differences in scores relating to stock type, grazing intensity, grazing timing and habitat impacts, but no single region scored higher than others overall.
  • Sites with Agri-Environment Scheme (AES) agreements were no more likely to be grazed than sites without AES – some subsidies were being paid without any active grazing taking place.
  • AES reduced grazing pressure but not sufficiently to achieve optimal conservation grazing requirements, indicating that AES has been an ineffective conservation mechanism on saltmarsh.
  • In the East, older AES sites scored substantially higher and approached optimal levels, suggesting that managers and advisers can improve outcomes by working together over longer periods.

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Improving the system

The authors argue that, although there is sound scientific evidence as to how saltmarshes should be managed, to provide positive conservation outcomes, there are problems when it comes to the translation of evidence into recommendations for hands-on management. It is also difficult to encourage land managers to implement recommendations when these go against traditional farming practices and economic gain. To improve the situation, Lucy and her colleagues suggest that:

  • When establishing agreements, it is helpful to provide detailed prescriptions that can guide land-managers.
  • AES payments need to take account of the costs of grazing a complex environment, which means thinking about the availability of cattle of appropriate ages at the right times of year, provision of fresh water and high-tide refuges, and the use of fences to divide up the saltmarsh, in order to provide a rotational grazing system.
  • Prescriptions that focus on numbers of cattle and timing of grazing are easier to follow than ones that focus on intensity and habitat condition.
  • Additionally, a more detailed and reliable system of auditing would be beneficial, to ensure that management activities take place to the necessary standard prior to payments.
  • Moving to a results-based scheme, where payments are made based on desirable outcomes, rather than on evidence of management, may improve the overall conservation value and economic efficiency of saltmarsh AES options.

Blog JoshIn conclusion

Raising cattle on saltmarsh is hard work, in terms of stock control, but requires no fertiliser inputs.  These ‘mobile mowing units’ stop saltings from becoming long and rank, thereby creating spaces in which a rich plant and grass community can flourish, where geese and waterfowl can graze during the winter months, and potentially providing nesting spaces for breeding waders, such as the amber-listed Redshank, breeding numbers of which are still declining.

Lucy and her RSPB colleagues conclude that Agri-environment Schemes are the only mechanisms through which saltmarsh conservation grazing can be implemented on a national scale, so it’s important to make sure that they are as effective as possible. By working together, it is hoped that policymakers, researchers and managers can refine conservation guidelines which are used to create management schemes that attract subsidies. They suggest that better value could be achieved through more sensitive use of current management activities or perhaps by linking payments to conservation outcomes, rather than on evidence of management.

blog cr RKThe noisy warning calls of a pair Redshank, as they encourage their chicks to hide, have earned the species the title ‘warden of the marshes’. Their calls also appear to be a warning cry about the state of Britain’s saltmarshes, despite the large amount of money being provided through agricultural subsidies and the good intentions of conservation organisations, agricultural advisers and graziers.

You can read more here:

Are agri-environment schemes successful in delivering conservation grazing management on saltmarsh? Lucy R. Mason, Alastair Feather, Nick Godden, Chris C. Vreugdenhil & Jennifer Smart. Journal of  Applied Ecology. May 2019.

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GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

Not-so-Common Sandpipers

April and May mark the start of the Common Sandpiper breeding season, as males display along rivers and streams and around the banks of lakes and reservoirs. Numbers in the United Kingdom have declined by 26% in just over 20 years, providing an increased focus to research that has been taking place over five decades.

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This tale focuses on a year in the life of Common Sandpipers, using material gleaned from the book Common & Spotted Sandpipers by Phil Holland (published by Whittles in 2018) but with new information from recent migration studies. Phil’s fascinating book also includes chapters about the habitats used by both species, the food that they eat, predators that eat them and the way that Common Sandpipers have adapted (or failed to adapt) to changes in Britain over the last 250 years.

Common or Spotted?

blog spottyThis blog is just about Common Sandpipers. The Spotted Sandpiper breaks up the circumpolar distribution of the Common Sandpiper, laying claim to the Americas. A big difference between the two species is the mating system, with Common Sandpiper pairs setting up territories in a conventional (although not particularly faithful) manner and Spotted Sandpipers using polyandry in a way that provides females with the potential to raise more chicks in a year.

A female Spotted Sandpiper sets up a territory, attracts a male, lays a clutch of eggs which her partner then incubates, attracts and lays another clutch for another male, and so on. In Phil Holland’s book, there is an example of one female laying five clutches with three males over the course of six weeks – representing an egg-mass of four times her own body weight. There is plenty more fascinating stuff about Spotted Sandpipers in the book.

Population changes

The Breeding Bird Survey indicates a fall in breeding Common Sandpiper numbers in the UK of 26% between 1995 and 2017, with a bigger decline in England (49%) than in Scotland (23%). Other BTO-led surveys suggest that the nationwide declines started in the mid-1980s, with a British fall of over 50% during this longer period. There have been similar declines elsewhere in Europe. Common Sandpiper is now amber-listed, as a species of conservation concern, in the UK.

Breeding season

Much of the detailed breeding season work on Common Sandpiper in the UK was undertaken in the English Peak District by Phil Holland and then Derek Yalden, to whom Phil Holland’s book is dedicated, with information supplemented by other bird ringers, particularly Tom Dougall in Scotland.

blog nestMale Common Sandpipers tend to arrive back from Africa a little earlier than females – with a median difference of just two days – and it is the male that holds the territory (females in Spotted Sandpiper). If two birds that were together in the previous year arrive back on site then they will usually pair up again. When they don’t, it’s because of a mismatch in the timing of arrival or because the female moves to a better territory or more experienced mate. It may not be easy to spot infidelity in the field but genetic analysis in Scotland showed that males were incubating the eggs that had not been fertilized by them in 5 out of 26 cases (Mee paper link). On two of these occasions, none of the clutch of four belonged to the male that was sitting on them.

blog sittingDuring the incubation period, males typically take the 15-hour night-shift and females the 9-hour day-shift. During their ‘time off’, males devote time to territory defence and look-out duties. Chicks hatch after three weeks and the growth rate of chicks is highest in warm, dry and sunny weather. Males do most of the parenting of chicks; females usually leave before the chicks fledge and occasionally, if there are late nests, before the eggs hatch. Experienced parents raise more chicks to the point of fledging. There is more fascinating detail in the book, which includes full references for papers.

The southward migration

blog mapMovements of ringed birds from Scotland and Northern England strongly suggested that adults left their breeding territories and headed south within the UK, to fatten up prior to migration to Africa. British ringers have caught birds weighing up to 80 g, twice the pre-fattening weight, suggesting the potential to move a long way in the next flight.

Geolocators have been a revelation, enabling individuals to be tracked for the whole annual cycle between one breeding season and the next. The story of the first UK Common Sandpiper to return with a functioning geolocator was told in Wader Study by Brian Bates and colleagues, revealing two stops in western Britain, a three-day break in Morocco and a direct flight to Senegal.

There’s a WaderTales blog about the use of geolocators on Green Sandpipers that gives more information about how data are collected and discusses how these devices affect the behaviour of the birds that carry them.

A follow-up paper by the same Scottish team from Highland Ringing Group, this time with Ron Summers as lead author, has been published in the Journal of Avian Biology (Non-breeding areas and timing of migration in relation to weather of Scottish-breeding common sandpipers). It summarises the journeys of 10 tagged birds, with a median departure date from Scotland of 9 July. Some individuals spent time fattening in England, then most birds staged for longer in Iberia before continuing to West Africa, with a median arrival time of 28 July. The southward migration from Scotland took an average 17.5 days (range 1.5–24 days), excluding the initial fuelling period.

Pere Josa and colleagues have studied Common Sandpipers in The Ebro Delta of Spain, writing up their findings in Wader Study as Autumn migration of the Common Sandpiper. These stop-over adults migrate seven weeks earlier than juveniles, putting on enough fat to travel at least 2000 km on the next stage of their journeys, which would take them to North Africa. They would need to refuel if they were to make it as far as West Africa, which is the main wintering area for Common Sandpipers. Common & Spotted Sandpipers provides many more examples of ringing and body condition studies carried out in stop-over sites between Sweden and Morocco.

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Life in the south

blog mangroveSix of the tagged birds from Scotland spent most of the non-breeding season (October–February) on the coast of Guinea-Bissau, suggesting that this is a key area. Single birds occurred in Sierra Leone, Guinea, the Canary Islands and Western Sahara.

Coastal West Africa provides two major habitats for Common Sandpipers: mudflats associated with mangroves (as shown to the right) and rice fields. Phil Holland takes the reader around the mangroves of the world and discusses the numbers of Common and Spotted Sandpipers that have been reported from different countries. He suggests that rice fields provide supplementary food for birds that are mainly coastal winterers and wonders if the depletion of mangrove habitat  has affected Common Sandpipers.

The northward migration

The last day in West Africa, for the 10 tagged individuals, ranged from 3 to 20 April and the arrival dates in Scotland ranged from 19 April to 6 May. The birds typically staged twice between Morocco and the Channel and the median time taken for active migration was 16 days (range 13.5–20.5 days). The main migration strategy involved short- and medium-range flights, using tail-winds in most cases. Birds that left later spent shorter periods of time at stop-over locations.

Why so few Common Sandpipers?

survival blogAs discussed in the WaderTales blog summarising Patterns and processes in shorebird survival rates: a global review by Verónica Méndez in IBIS, the apparent annual survival rate of the Actitis family is low, with a calculated rate of 0.718 for Common Sandpiper and 0.497 for Spotted Sandpiper. Whether this has always been the case is unknown, of course, and Phil Holland points out that these calculations are based upon observations of colour-ringed individuals, at least some of which change territories between years, potentially leading to a reduction in detectability.

An analysis of demographic data for a small population of Common Sandpipers in northern England, by James Pearce-Higgins and colleagues indicated that the long-term decline in numbers was not due to low breeding success, instead being due to a low return rate of adults, which was negatively associated with the winter North Atlantic Oscillation. This suggested that climate change might be affecting annual survival.

In their paper about the 10 Scottish birds, tracked using geolocators, Ron Summers and colleagues matched movements to meteorological data during the migration period. They suggest that the weather during the southward migration was unlikely to adversely affect birds but that strong cross-winds or head-winds during the northward migration to the breeding grounds may do so. This accords with work on Black-tailed Godwits by Nathan Senner and colleagues which showed that the survival of satellite-tagged birds was reduced on the northward crossing from West Africa to Europe.

For the moment, there is no clear explanation for the fall in Common Sandpiper numbers. Given that it’s hard to change the climate or to study what might be happening to Common Sandpipers feeding amongst the mangroves of West Africa, it seems wise to focus on habitat and species protection in breeding areas. We also need to keep monitoring productivity and return rates of breeding populations in the UK and elsewhere, especially in the English Peak District.

Common & Spotted Sandpipers

blog coverPhil Holland’s book is a fascinating insight into the lives of the two Actitis species. It’s almost as if the reader is allowed to sit on a bank with the author and share intimate moments with these birds. Derek Yalden would have been delighted to see the project come to fruition but acknowledge that there is still much to learn. Who will spend the next 40 years studying Common Sandpipers in Europe and Africa or Asia and Australasia, or Spotted Sandpiper in the Americas?

Book Details

Common & Spotted Sandpipers is published by Whittles Books. You can find out more by following this link.

New research

blog CKThomas Mondain-Monval (Lancaster University) is trying to understand the UK-decline of Common Sandpipers.  He is studying a breeding population in the Yorkshire Dales National Park, tracking birds on migration and studying them at a wintering site in Djoudj National Bird Sanctuary, Senegal.  Birds are fitted with colour rings and geolocators in the UK and Senegal, and Thomas would appreciate reports of migrating birds, which are likely to appear in Iberia, France and England. If licensed bird-ringers see birds with geolocators and spot opportunities to catch them and remove the trackers, this would be very helpful. Thomas can be contacted at:

t.mondain-monval@lancaster.ac.uk


GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

Ireland’s wintering waders

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There’s still space for a few Knot

The island of Ireland is a great refuge for wintering waders, washed as it is by the warm waters of the Gulf Stream. It’s just a quick hop across the Atlantic from Iceland for Black-tailed Godwits, Golden Plovers, Redshanks and Oystercatchers. For birds travelling from Siberia, such as Bar-tailed Godwits and Grey Plovers, it’s a longer journey but one that’s well worth making.

If Ireland is such a great destination for shorebirds, why do the latest population estimates reveal a decline of nearly 20% in wader numbers in just five years?

This blog summarises the wader information, published in Estimates of waterbird numbers wintering in Ireland, 2011/12 – 2015/16 in Irish Birds. The totals in the report are split into counts for the Republic of Ireland and Northern Ireland but, given that waders don’t recognise borders, most of the comments in this blog relate to the whole of Ireland. The results for 2011-16 have been compared to the equivalent figures for 2006-11 and set in the context of the totals of wintering waders throughout the East Atlantic flyway, as combined by Wetlands International. The Irish data were collected by the amazing volunteers who make monthly, winter counts for I-WeBS (BirdWatch Ireland & National Parks & Wildlife Service) and WeBS (BTO/RSPB/JNCC in Northern Ireland).

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Headline figures

Fifteen species are considered in this report. The most numerous are Lapwing and Golden Plover, which account for an estimate over 170,000 individuals between them, whilst the smallest contributions are made by Purple Sandpiper (662) and Greenshank (1317). In total, the average estimated number of waders in the winters during the period 2011-16 is 429,170 birds but it should be noted that this total excludes two widespread and common species – Woodcock and Snipe – as well as the enigmatic Jack Snipe. To update previous estimates for these three species, which were last made using distribution and abundance data collected during Bird Atlas 2007-11 fieldwork, it would be necessary to run a special inland survey. There is also some question about Lapwing and Golden Plover numbers, simply because so many of these birds are found in areas that are not covered by monthly waterbird counts.

Biggest changes

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The Irish Sanderling population has increased by 13.2% in five years

The combined average winter maximum count of the 15 wader species examined in the report declined by 102,310 birds (19%) in the five-year period between 2006-11 and 2011-16. This is extremely worrying. If Lapwing and Golden Plover are excluded from consideration, as there is uncertainty about the completeness of counts, there are five species that are of particular concern; Knot numbers dropped by more than 40% and Oystercatcher, Dunlin, Redshank and Turnstone numbers by more than 20%. The Purple Sandpiper population estimate dropped by over 30% but relatively small numbers of this species are encountered around the rocky coast of Ireland. The only species to show increases were Sanderling, Bar-tailed Godwit, Black-tailed Godwit and Greenshank.

In a previous WaderTales blog, there is detailed information about population estimates for Great Britain: Do population estimates matter? In Great Britain there were similar rates of decline for Redshank and Turnstone (measured over an eight-year, rather than five-year period) but much smaller falls for Knot, Oystercatcher and Dunlin. The possible causes of the changes in Ireland are discussed in the paper in Irish Birds. They include flyway-scale declines (e.g. Knot and Curlew) and the possibility that more birds from the east are now wintering on the coasts of mainland Europe (e.g. Dunlin and Grey Plover).

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European context

Blog tableThe table alongside gives an indication of the relative importance of Ireland, Great Britain and, together, the British Isles to the birds that use the East Atlantic flyway during the winter period. The three columns show the percentage of each species found in each of the three regions. Summarised international counts, as used in the paper, were kindly provided by Wetlands International. In the case of four species, Ireland is host to a significant proportion of the Icelandic breeding population (Oystercatcher, Golden Plover, Black-tailed Godwit and Redshank).

Notes: As mentioned earlier, there are questions about the precision of estimates for Lapwing and Golden Plover, although the population trends are reliable. The Ringed Plover percentage seems high (98% for British Isles) but this may well reflect the fact that the Non-estuarine Waterbird Survey has uncovered significant numbers of the species on the open shores of Great Britain. These extra birds are included in the new totals for GB but not in the flyway total. The percentages for Black-tailed Godwit seem low, as discussed further down.

Ireland is particularly important for Golden Plover, Ringed Plover, Bar-tailed Godwit and Black-tailed Godwit, as well as for the Icelandic subspecies of Redshank. Greenshank is excluded because the percentages are below 1% of the flyway population for Ireland and for Great Britain.

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11% of Bar-tailed Godwit on the East Atlantic Flyway spend the winter in Ireland

Although there are important populations of breeding waders in Ireland, the shores and wet fields of the island really come into their own during July and August, when the first ‘winter’ waders arrive, and they only become quiet again in April and May, when the last birds head north and east to nest. A successful breeder is likely only to be away for four or five months, meaning that these waders will spend by far the largest part of the year in Ireland. The island is even more important for immature birds. Young Oystercatchers that arrive from Iceland, Scotland or perhaps Norway when just a few months old are likely to spend the next 30 months in Ireland before making their first trip north. There is a WaderTales migration blog about the Oystercatchers that fly from Iceland: Migratory decisions for Icelandic Oystercatchers.

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Curlew in the Republic

Curlew numbers in the Republic of Ireland illustrate the relative importance of the country for breeding and non-breeding populations. The winter population estimate for Curlew in the Republic is 28,300 but the most recent survey conducted by BirdWatch Ireland and NPWS, as summarised in the WaderTales blog Ireland’s Curlew Crisis, reveals that the number of breeding birds has crashed to just 138 pairs. Accounting for young Irish birds that have not started to breed, and even if we assume that all Irish birds stay in the country for the winter, then the total number of home-grown Curlew seen in non-breeding flocks is at most about 400. This means that every winter flock of 70 Curlew will contain an average of just one Irish bird. Far more deliver their curl-ew calls with a Scottish, Finnish or Swedish ‘accent’. The map below shows the migration pattern for Curlew ringed in or found in Britain & Ireland.

blog migration map

Black-tailed Godwit

In the table above, it looks as if 18% of Iceland’s Black-tailed Godwits spend the winter in Ireland. This is probably an underestimate of the importance of the Republic of Ireland and Northern Ireland to the species. The flyway total for Black-tailed Godwit is given as between 98,000 and 134,000 in the Irish Birds paper and the percentage figure is based on 110,000. These three figures are almost certainly too high, as they build upon country-based estimates that have subsequently been revised. The true figure is likely to be around 60,000 to 65,000 (J. Gill pers. comm.), which would suggest that the maximum winter count in Ireland of 19,800 represents at least 30% of the islandica Black-tailed Godwits. Add in extra birds that moult in Ireland in the autumn, before moving further south to countries such as Portugal, and other birds that spend spring months on the island, and Ireland becomes even more important for Black-tailed Godwits!

blog BTMost birdwatchers might associate flocks of waders with estuaries but Black-tailed Godwit is an excellent example of a species that also relies on inland fields, either close to estuaries or along river valleys. Whilst undertaking PhD research on Black-tailed Godwits in south-east Ireland, Daniel Hayhow showed that there is insufficient time to find enough estuarine food during the mid-winter tidal cycles, with birds topping up their resources on grassland. You can read more about the energetic consequences of choosing to winter in eastern England, Portugal and Ireland in this blog: Overtaking on migration. Site designation and planning decisions need to take account of the grassland feeding requirements of Black-tailed Godwits and other waders that do not spend all of their time on estuaries, particularly Curlew.

Conservation implications

Some of the issues facing waders may be related to threats that species face in the breeding grounds. However, it may be easier to introduce measures that provide better protection and feeding opportunities in the wintering area, as ways of maintaining populations through the non-breeding season, than it is to deal with problems in the High Arctic. (Although we can all help by reducing carbon emissions, in order to minimise global warming, of course).

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Reading the report, I was reminded of the need to consider a range of conservation issues:

  • Care needs to be taken when considering shoreline developments. These can directly remove habitat or squeeze the width of the intertidal zone.
  • Increased harvesting of shellfish can affect species such as Oystercatcher and Knot and brings risks of introducing alien species and diseases.
  • In the drive to cut carbon emissions, tidal, wave and wind power developments need to be sited in appropriate places.
  • Off-shore harvesting of growing kelp beds has been suggested, as a way of producing fertiliser and biofuels. This process could reduce protection for beaches and change the availability of resources for species such as Turnstone and Sanderling.
  • Grassland areas need to be considered (and not just estuaries) when planning protection for species such as Curlew and Black-tailed Godwit.

blog RKPaper

Estimates of waterbird numbers wintering in Ireland, 2011/12 – 2015/16. Brian Burke, Lesley J. Lewis, Niamh Fitzgerald, Teresa Frost, Graham Austin, and T. David Tierney. Irish Birds No. 41, 1-12.

There is a complementary paper in British Birds, covering Great Britain. The wader information is summarised in this blog: Do population estimates matter?


GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

Do population estimates matter?

blog top godwitsThis month (March 2019) saw the publication of Population estimates of wintering waterbirds in Great Britain, which includes all the wader species from Little Stint to Curlew. Given that the Wetland Bird Survey already covers about 2000 wetlands and provides annual monitoring, why do we need to know the total number of birds in Great Britain?

I suggest four reasons:

  • If we count the number of Curlew and we have a figure for the European population then we know that Great Britain is responsible for nearly 20% of Europe’s Curlew each winter, thereby strengthening the case for national conservation action;
  • If we have a national figure, then we know that a flock of 2000 Black-tailed Godwit represents (as it turns out) over 5% of the British total, which is a useful criterion when assessing the conservation importance of individual sites;
  • blog GKPopulation totals help to put annual percentage changes into context;
  • And simply because people ask questions such as “how many Greenshank are there in the country during the winter?”

So, here’s the bottom line. In their 2019 review of waterbird numbers in British Birds, a team from BTO, WWT, JNCC & RSPB reveal that an estimated total of 4.9 million waders spend the winter in Great Britain. That’s about one third of all waders on the East Atlantic Flyway. Impressive!

Please note that Northern Ireland figures are included in an upcoming report for the island of Ireland.

Making the counts

The population estimates owe a lot to those who undertake monthly Wetland Bird Survey (WeBS) counts on estuaries, lakes and waterways, during the winter months, year in and year out. Counts from the period 2012/13 to 2016/17 are used in the population estimates that form the basis for the 2019 review. WeBS data have many other uses, as you can read here: Wetland Bird Survey: working for waders.

blog CUFor species of wader that also make use of the open coast, the Non-estuarine Waterbirds Survey of 2015/16 (or NEWS III) provided additional data, updating the NEWS II figures from 2006/07. The vast majority of our wintering Purple Sandpipers are found on open beaches and rocky shores, as well as large numbers of Turnstone, Ringed Plover and Sanderling, together with significant numbers of Oystercatcher, Curlew and Redshank. There’s more about NEWS in this slightly dated blog: NEWS and Oystercatchers for Christmas.

The last assessment of winter wader populations was made by the Avian Population Estimates Panel and published in British Birds in 2013 as Population estimates of birds in Great Britain and the United Kingdom (APEP3). In here, estimates for waders were largely based on WeBS data for the period 2004-09 and NEWS II. The new assessment is presented as Population estimates of wintering waterbirds in Great Britain and also published in British Birds. It uses WeBS information for the period 2012-17 and NEWS III data. Effectively, there is an 8-year or 9-year difference between the two sets of figures.

The biggest losers

blog graphicGreat Britain is extremely important in the context of the East Atlantic Flyway, as is obvious from the fact that the area holds nearly five million waders. The WeBs counts already monitor the ups and downs on an annual basis but this review provides an opportunity to turn the percentages into actual numbers. It is concerning that, over a period representing less than a decade, the average maximum winter count for six of the species that were surveyed dropped by a total of over 150,000. These big losers were Knot, Oystercatcher, Redshank, Curlew, Grey Plover and Dunlin, ordered by number of birds lost, with Knot seeing the biggest absolute decline.

In preparing the new estimates for the British Birds paper, an opportunity was taken to refine the way that populations are calculated, based on Use of environmental stratification to derive non-breeding population estimates of dispersed waterbirds in Great Britain, by Verónica Méndez et al. The new methodology explains some of the differences between percentage changes reported by WeBS and the percentage changes obtained by comparing the latest population estimates to those in APEP3.

blog KN graphic

The Knot estimate dropped from 320,000 to 260,000. This figure is higher than might be expected from the counts that take place at sites covered by WeBS, being larger than the ten-year decline of 14% reported in the last WeBS report. Knot are mobile species within the North Sea and Atlantic Coast wintering area and it is possible that British losses may be explained, at least to some extent, by redistribution.

blog oyc graphThe drop in Oystercatcher numbers from 320,000 to 290,000 appears to be less than 10%, compared to a ten-year decline of 12% on WeBS. Improved analysis of NEWS data helped to add some more birds to the open-coast estimate so the 10% fall may underestimate the seriousness of the Oystercatcher situation. The 25-year Oystercatcher decline on WeBS is 26%, which is not surprising if you look at the changes to breeding numbers in Scotland, where most British birds are to be found. There’s more about this in: From shingle beach to roof-top.

blog RKThe Redshank decline of 26,000 is higher than would be predicted from WeBS figures, suggesting a drop of over 20% since APEP3, rather than ‘just’ 15% for the ten-year WeBS figure. This is a species that also features strongly in the Non-estuarine Waterbird Survey and that might explain the difference. Wintering Redshank are mostly of British and Icelandic origin, with the Breeding Bird Survey (BBS) suggesting a ten-year decline of 24% in our British breeding birds.

The Curlew is now globally recognised as near-threatened. The latest winter estimate is 120,000, down from 140,000 in APEP3. The new total represents between 14% and 19% of the European population, which means that we have a particular responsibility for this much-loved species. Only the Netherlands holds more wintering Curlew than Great Britain. Is the Curlew really nearly-threatened? is one of several blogs about Curlew in the WaderTales catalogue at www.wadertales.wordpress/about .

blog 2 DNIt has been suggested that the long-term declines of Grey Plover and Dunlin  may be associated with short-stopping, with new generations of both species wintering closer to their eastern breeding grounds than used to be the case. WeBS results indicate a 31% drop in Grey Plover and a 42% drop in Dunlin, over the last 25 years. There was a loss of 10,000 for both species between APEP3 and the new review, representing declines of 23% and 3% respectively.

The biggest winners

There are four big winners in the period between APEP3 (2004-09) and the new review (2012-16), although, even here, not all as it seems.

The Avocet has seen further dramatic gains. with the estimated wintering population rising to 8,700. The increase is not quite as big as might have been expected, based on the 43% rise seen in ten years of WeBS counts, but it is still a dramatic continuation of a 40-year trend.

The numbers of Bar-tailed Godwit and Ringed Plover are both substantially higher but at least a proportion of each of these changes is linked to the better coverage and more sophisticated sampling methods that were discussed earlier. Bar-tailed Godwit increases may also reflect redistribution around the North Sea.

blog BW graphOne of the consequences of improved statistical techniques, as used this time around, is the apparent decline in the estimated population of Black-tailed Godwit. The new figure of 39,000 is 4,000 smaller than in APEP3, despite the fact that the WeBS graph clearly shows an increase. Interpolation using WeBs figures suggests that the earlier population estimate should have been 31,000, rather than 43,000.

There are other winners too, as you can read in the paper. At the start, I posed the question “how many Greenshank are there in the country during the winter?”.  The answer is 810, representing an increase of 200 since APEP3.

Game species

The estimates for the three wintering waders that are still on the UK quarry list have not changed since APEP3 (published in 2011) as there are no new data available.

Golden Plover: The winter estimate remains as 400,000, as there has been no comprehensive, winter survey since 2006/7. Large numbers of Golden Plover arrive from Scandinavia, Europe and Iceland in the late summer, joining the British birds that choose not to migrate south or west. The GB breeding population is probably less than 50,000 pairs. Most breed in Scotland which has seen a breeding decline of 23% in the period 1995 to 2016 (BBS). Golden Plover is still ‘green listed’.

snipe-headerSnipe (Common): The winter estimate remains as 1,100,000 – a figure that was acknowledged in APEP3 as being less reliable than that of most species. At the same time, the GB breeding population was estimated as 76,000 pairs, indicating at least a 4:1 ratio of foreign to British birds, and that does not take account of the number of British birds that migrate south and west. Snipe are ‘amber listed’ but BBS suggests a recent increase of 26% (1995-2016). There is a WaderTales blog about  Snipe and Jack Snipe.

Woodcock: The winter estimate remains as 1,400,000 – another figure that is not considered to be particularly precise, with much variation between years. The diminishing breeding population is dwarfed by winter numbers, as you can read in this WaderTales blog, with increased attention being given to ways to afford better protection of red-listed, British-breeding birds.

January counts

blog BTThe paper in British Birds also includes a table of January population estimates, to provide data that are comparable to mid-winter counts in other countries. These figures are used in waterbird monitoring for the International Waterbird Census for the African Eurasian Flyway. The main table (and figures mentioned above) are average maximum winter counts (in the period September to March). Black-tailed Godwit is one species that illustrates the difference, with a mean of 30,000 in January and a mean peak count of 39,000. Having moulted in Great Britain, some Black-tailed Godwits move south to France and Portugal in late autumn, returning as early as February. January counts are therefore substantially lower than early-winter and late-winter counts. There is more about the migratory strategy employed by Black-tailed Godwits that winter in southern Europe in Overtaking on Migration.

Looking forward

blog BB coverThe authors have done a tremendous job. They have refined the way that estimates are calculated, they have combined the results from WeBS and NEWS III, and they have delivered population estimates for 25 wader species and many more other species of waterbirds. These population estimates will be used in conservation decision-making until the next set of numbers becomes available. Meanwhile, thousands of birdwatchers will count the birds on their WeBS patches in each winter month, every year. Without them, this paper could not have been written.

Before the next assessment, there will need to be another NEWS survey, to check up on species that use rocky and sandy shore birds, such as Purple Sandpipers, Turnstone and Curlew. Hopefully, there will also be a dedicated survey to assess Lapwing and Golden Plover numbers and perhaps we might find a way to refine the old estimates for Woodcock, Snipe and Jack Snipe.

Paper

Population estimates of wintering waterbirds in Great Britain. Teresa Frost, Graham Austin, Richard Hearn, Stephen McAvoy, Anna Robinson, David Stroud, Ian Woodward and Simon Wotton. Published in British Birds Volume 112. March 2019.

British Birds is a subscription journal. The issue containing this paper can be purchased separately. At some stage, the paper will become free-to-view.

blog flying godwits

 


GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

Ireland’s Curlew Crisis

To put the rapid loss of Ireland’s breeding Curlew into context, it’s equivalent to the human population of the Republic dropping from 4.8 million to less than 200,000.

blog muddy edgeIn their paper in Wader Study, the journal of the International Wader Study Group, Barry O’Donoghue and his colleagues reveal the results of the 2015-17 survey of breeding Curlew in the Republic of Ireland. The emerald isle used to be a haven for Curlew but there are now dire warnings that the species could be lost as a breeding species. Various estimates suggest that there were between 3,300 and 12,000 pairs in the 1980s but the current number may be as low as 138 pairs. That’s a fall of 96% in about thirty years.

The latest survey

Surveys in the summers of 2015, 2016 and 2017 focused upon areas that were known to hold breeding Curlew in the previous few years. Sites were identified, using data from Bird Atlas 2007-11 (BTO, BirdWatch Ireland & SOC), the National Parks and Wildlife Service (NPWS) and BirdWatch Ireland, and then extended by 3 km to try to cover any satellite pairs. Additional records were sought from NPWS Rangers (who actively monitor wildlife in their patches across the country) and BirdWatch Ireland branches, supported by a public appeal, using traditional and social media. For details of the survey methods, please see the paper ( link below).

Doing the sums

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Loss of habitat is a major issue for Ireland’s Curlew – blocks of forestry and fragmentation.

Volunteers and staff, who surveyed previously-occupied areas, discovered 128 breeding pairs during the summers of 2015-17. Nationwide publicity added an additional ten pairs, making a minimum count of 138 pairs of breeding Curlew in the whole of the Republic of Ireland. When comparing this figure to historical estimates of national populations, the authors use the conservative figure of 3300 pairs, which is at the lower end of the smallest estimate. This suggests a drop of 96%. If the highest previous estimate of 12,000 pairs had been used, we would be talking about a decline of 99%.

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Curlew chicks are a rare sight – productivity is very low in Ireland

Curlew were recorded at densities of approximately three pairs per 1,000 ha of suitable habitat (0.3 pairs per km2). This suggests that, in these occupied areas of raised bog, wet grassland, wet heath and upland blanket bog, Curlew are living in similar densities to those of the 1980s. They are just found in a much reduced total area.

One positive finding is that 56% of the surveyed Curlew population occurs in protected sites, whether Special Protection Areas (SPAs) or Special Areas of Conservation (SACs) designated under European legislation, and/or Natural Heritage Areas (NHAs) designated under national legislation.

Caveats

The focus of the 2015-17 survey was upon sites that were known to hold Curlew during the period between 2007 and 2014. In an ideal world, there would have been surveys of randomly selected areas in other parts of the country, to establish the number of birds that might have been missed. This would have been an expensive exercise and the consequences are probably not particularly significant because:

  • blog mapDuring the breeding seasons of 2008 to 2011, the whole of Ireland was covered for the Bird Atlas.  The map alongside shows the breeding distribution from this joint BTO, Birdwatch Ireland and SOC project. It shows that there are many areas that no longer have breeding Curlew (black triangles).
  • Curlew are highly site-faithful. Birds are long-lived and unlikely to move between years, so any site occupied in 2011, for instance, would be expected still to hold some of the same birds four years later.
  • Curlew return to breed close to areas where they were raised. The 3-km buffer zone is likely to have picked up young birds setting up their own territories, although precious few chicks fledge successfully these days, anyway.
  • The Curlew is a much-loved bird. A major publicity campaign led to the discovery of only 10 pairs outside the main study areas. If a further 30 pairs were missed (which seems high, representing only a 25% success rate in the call for additional records) then this would only change the ‘96% decline’ headline to a ‘95% decline’.

blog numeniiniWhat has gone wrong?

This blog focuses on the results of the 2015-17 Irish Curlew  survey. Previous WaderTales blogs provide information that sets these declines in context and discuss the problems being faced by the species.

There is a global crisis for large waders as you can read in this review: Why are we losing our large waders?

Each autumn, Irish Curlew are joined by thousands of migrants, largely from Finland, Sweden and Britain. There are still large flocks of Curlew in winter, so it may be hard to persuade people that the Curlew is in trouble. Here are the arguments: Is the Curlew really near-threatened?

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The key issue for breeding birds is habitat loss, as discussed in Mary Colwell’s excellent book Curlew Moon, reviewed here: Curlew Moon.

A review of the associations between Curlew and their habitats suggest that conservation action needs to focus on habitat restoration and reducing the impacts of predators (the latter, at least in the recovery phase): Curlews can’t wait for a treatment plan.

The way that land is grazed has a major impact on breeding Curlew: Sheep numbers and Welsh Curlew.

Acknowledgements and action

blog logoThe 2015-17 survey in Ireland was commissioned by the National Parks and Wildlife Service. Confirmation of the severity of the decline led to the establishment of a Curlew Task Force in January 2017 and a Curlew Conservation Programme, aimed at increasing the productivity of remaining Curlew pairs. CCP logo adapted from original artwork by Anne Harrington Rees.

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Fencing and habitat creation

This study has identified strongholds for breeding Curlew in the Irish Republic and conservation action is currently being implemented in Donegal, Kerry, Kildare, Galway, Leitrim, Mayo, Monaghan and Roscommon. For information on what is an innovative approach to tackling the Curlew crisis, read more about the National Parks and Wildlife Service’s Curlew Conservation Programme here.

Paper

The full paper is in the journal Wader Study. Click on the title below for a link:

O’Donoghue, B., A. Donaghy & S.B.A. Kelly. 2019. National survey of breeding Eurasian Curlew Numenius arquata in the Republic of Ireland, 2015–2017.

Wader Study 126(1): doi:10.18194/ws.00130

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GFA in Iceland

WaderTales blogs are written by Graham Appleton, to celebrate waders and wader research.  Many of the articles are based on previously published papers, with the aim of making wader science available to a broader audience.

@grahamfappleton

The waders of Northern Ireland

blog CU postNorthern Ireland is a great place for wintering waders but the same can no longer be said for its breeding species. There are far too few places left in which Curlew bubble and Snipe drum.

Waders provide some of the best birdwatching spectacles in Northern Ireland, as flocks swirl around coastal estuaries, when the tide rises on a winter’s day. Birds fly in from as far away as Canada and Russia but there are particularly strong links to Iceland, about which there will be more later. Every year, winter counts by volunteers, who help with the Wetland Bird Survey, alert us to the ups and down in wintering populations on loughs and estuaries. Unfortunately, we know much less about breeding species such as Lapwing, Redshank, Snipe and Curlew – four species that feature in a new Northern Ireland survey in the summer of 2019. Although the annual Breeding Bird Survey monitors birds such as Song Thrush and Willow Warbler, waders are just too thinly spread in Northern Ireland for it to be possible to pick up any year-to-year changes. That’s why they need a special survey.

blog L flightWe know that there were some great wader hot-spots in the years 1985 to 1987, when a major Northern Ireland survey took place, and that large drops in numbers were reported in 1999 and again in 2013, after other dedicated surveys, but what is happening now? Are there still places where Snipe drum and Curlew bubble? The BTO in Northern Ireland is asking local and visiting birdwatchers to revisit some of the best places that were identified in previous surveys, to look for breeding waders and to assess the habitats that remain. This work complements work being undertaken by RSPB Northern Ireland. If you think that you may be able to help click here to find more information.

Not looking good?

Although it would be nice to be proved wrong, the expectation is that breeding wader numbers will have declined still further. This means, of course, that any remaining sites that still hold species such as Redshank and Lapwing, are going to be even more important than they were thirty years ago. Pessimism is based on trends elsewhere; numbers of breeding waders are falling throughout the UK and increased agricultural intensification within the Republic of Ireland has caused sharp declines in the focal species of this survey – Lapwing, Redshank, Snipe and Curlew. The following notes give some highlights about Northern Ireland’s waders and point out some of the things that we don’t know (yet).

Lapwing

blog Lap mapThe Lapwing has quietly disappeared from much of Northern Ireland over the last fifty years. The black triangles in the map alongside represent 10-km squares that lost their breeding Lapwings between the two atlases of 1968-72 and 2008-11. Previous Northern Ireland surveys of breeding waders in 1985-87 and 2013 suggest that the number of pairs dropped from an estimated total of 5250 to a total of 860 – that’s a loss of 5 out of 6 pairs. The new survey this summer will update breeding numbers in the species’ heartland areas, as long as sufficient volunteers step forward to help with coverage. (Here’s a link to the results of the 2013 Northern Ireland wader survey.)

Redshank

blog RKThere is no recent estimate for the number of breeding Redshank in Northern Ireland. Across the UK, the Breeding Bird Survey suggests that we have lost 41% of breeding birds since 1995, and the decline was well underway by then. The survey this year provides a good opportunity to learn as much as possible about this threatened species.

In the late summer, the tiny Northern Ireland population is joined by Redshank from Iceland and Scotland. There are also small a number of movements linking Northern Ireland with Wales and England; some of these might be of birds from further east in Europe that were ringed in Britain. Strangford Lough peak counts of over 2000 in October illustrate just how much of an influx there is each autumn.

Snipe

blog SN mapThe lowland wader survey in 1985-87 suggested that the Northern Ireland population of Snipe was about 5725 pairs. By the time of the next survey in 1999, that number had dropped to 3993 and then to 1123 in 2013. That’s a drop of 80%. Snipe seem very sensitive to habitat change, especially drainage. The map alongside shows the change in abundance between 1988-91 and 2008-11 across Britain & Ireland. There is an interesting mix of losses (grey) and increases (orange) in Northern Ireland. It will be great if the 2019 survey picks up some new Snipe hot-spots. One of the key elements of the fieldwork this year is to record habitat data and field-use. What habitats do Snipe still breed in and can these be expanded and replicated elsewhere within Northern Ireland?

blog SN groundThere’s a WaderTales blog about Snipe & Jack SnipeMany of the birds that are seen in Northern Ireland in the winter have flown across the Atlantic to escape the snow and cold of Iceland but there are also large numbers from Scandinavia and continental Europe

Curlew

The Curlew is in huge trouble across the whole island of Ireland. Surveys of random squares in 1985-87, 1999 and 2013 suggest that the number of breeding pairs in Northern Ireland dropped from 5000 to about 500 over the period. There is talk about potential extinction as a breeding species in Ireland and Wales. This may seem ridiculous when you can see flocks totalling 2000 birds around Lough Foyle, on a winter’s day. However, these are almost exclusively migrants, from Finland, Scandinavia and Scotland. One of the hopes is that the new survey will pinpoint new hot-spots for Curlew. There is already concerted action to try to bolster numbers through the Lough Erne Landscape Partnership.

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Other Northern Ireland waders

Oystercatcher: Many wintering Oystercatchers leave Northern Ireland in the spring, heading for Iceland, Scotland or perhaps Norway (more in this wader migration blog). By that time, resident adults will already have moved inland or onto beaches to breed and other birds will have returned from southern wintering areas.

blog RPFlocks of young birds are found on estuaries in the summer, as Oystercatchers typically don’t breed until three years old. We know that the number of breeding Oystercatchers in Scotland dropped by 38% between 1994 and 2017 but English numbers rose by 49% (read more here). We don’t know what’s happening in Northern Ireland.

Turnstone: Wintering birds are mostly thought to come from Greenland and Canada but a December capture of a bird from Sweden suggests that there might be a link to the east as well.

Ringed Plover: The new survey in Northern Ireland is not designed to monitor beach-nesting Ringed Plover. The most recent UK-wide survey of the species was in 2007, when the Northern Ireland population estimate was 147 pairs, similar to the estimate at the time of the previous survey, in 1987. In the same period, numbers dropped in Scotland (-42%) and England (-29%). Link to summary of paper.

blog GP mapGolden Plover: Ireland is a winter destination of choice for many Golden Plover that breed in Iceland. The recovery of a Belgian-ringed bird in 2006 suggests that some birds may arrive from the east as well. Wintering numbers are half what they were 25 years ago, according to WeBS data for Northern Ireland. A few breeding birds can still be found in the western parts of Northern Ireland but they have been lost from most other areas.

Grey Plover: It’s a long way from Siberia to Northern Ireland, so perhaps it is not surprising that not many Grey Plover make it this far west!

Knot: The best place to see Knot is in Strangford Lough, where numbers peak at over 4000 in some winters. The only two foreign-ringed birds were shot wearing Icelandic rings in 1957 and 1975 (when shooting them was legal). Northern Ireland’s wintering Knot probably breed in Greenland or Canada and migrate via Iceland.

Sanderling: The Sanderling that are seen around the coast in winter months, in small numbers, will almost certainly breed in Greenland. Numbers are higher in spring, when birds from further south stop off on their way to Iceland and then Greenland.

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Dunlin: This year’s survey of Lapwing, Redshank, Snipe and Curlew should really include Dunlin, as they share similar breeding habitat. However, it will be a very lucky volunteer who finds a displaying adult. Birds of the schinzii (green arrows) and arctica (yellow) race pass through in spring and autumn but the wintering birds are of the alpina race (orange).

blog WK mapWoodcock: The black triangles in the map opposite show the parts of Northern Ireland that have lost breeding Woodcock in the last 50 years. Data are from Bird Atlas 2007-11 (BTO, BirdWatch Ireland & SOC). In late autumn, birds fly in from counties such as Germany, Norway and Russia. See this blog.

Black-tailed Godwit: All is not gloom and doom in the world of waders; there are six times as many Black-tailed Godwits wintering in Northern Ireland as there were 30 years ago. Great views of these Icelandic visitors are provided at the RSPB reserve at Belfast’s Window on Wildlife. This blog explains why numbers have taken off in recent years.

Bar-tailed Godwit: The Bar-tailed Godwit that are seen in Strangford Lough and elsewhere are birds from northern Norway and Russia. There seems to have been little change in numbers, according to Northern Ireland WeBS counters.

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Whimbrel: A few Whimbrel drop in during autumn passage but far more appear in spring. Most Icelandic Whimbrel can fly straight to West Africa in the autumn but 80% stop off on the way north, many in Northern Ireland (see graphic above). You can read more here.

From Avocet to Pectoral Sandpiper

There is a supporting cast of waders that visit Northern Ireland. This blog provides more information on wader migration: Which wader, when and why?

A call for help

blog habitatAs must be obvious by now, BTO Northern Ireland is looking for volunteers to help with wader surveys in 2019. Sites are discrete lowland wet grassland areas, small enough to survey in one morning. At least two or ideally three visits to each site are required between mid-April and mid-June, with at least two weeks between each visit.

Each field or sub-unit needs to be covered on foot and the number of Lapwing, Curlew, Redshank and Snipe are counted per field. Some additional habitat recording is required, e.g. recording grazing, rush cover and estimating dampness.

blog mapSites are located in five broad areas (see map):

  • Loughs Neagh and Beg
  • Blackwater Catchment
  • Tyrone Fairy Water Bogs
  • Upper Lough Erne
  • Lower Lough Erne (these sites will be covered by the RSPB)

More details are available here, on the BTO Northern Ireland website. There will be a free training session on 29 March. Contact shane.wolsey@bto.org if you have any questions or would like to volunteer.

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GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland. He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

 

From local warming to range expansion

blog adultOver the last century, Icelandic black-tailed godwits have increased 10-fold in numbers and their breeding range has expanded throughout lowland Iceland. Although changing climatic conditions seem likely to have enabled this process, what is the mechanism? How might warmer conditions have contributed to this growth? This blog is a summary of a paper by José Alves and colleagues in Ecology & Evolution.

Setting the scene

If scientists are going to try to predict species’ responses to future climatic conditions, they will need to understand the ecological, behavioural and historical factors that influence how change happens. In other words, what mechanisms can link changes in climate with changes in population size and distribution?

tableAppreciating how local climate effects can potentially scale up to population-level changes requires climate effects to be measured across a population. Iceland is a great place to study these processes as it has been getting warmer since at least 1845, as measured by one of the longest temperature time-series in the world. The country hosts internationally-important breeding populations of many migratory bird species, for which changing climatic conditions could have important implications, including Black-tailed Godwit. The data in the table alongside have been extracted from a report to AEWA that was discussed at the 12th Standing Committee in Jan/Feb 2017.

A booming population

godwit spread

Expanding breeding range in Iceland

In the early 1900s, Black-tailed Godwits were restricted to the southern lowlands of Iceland but, since then, birds have gradually colonised coastal lowland areas throughout the country, with larger areas closer to occupied sites being colonised first (as described in this WaderTales blog). The population now numbers over 50,000 individuals, which is likely to represent an approximately 10-fold increase over the last century.

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Newly hatched chicks, still in their nest-cup, well hidden in grass

Icelandic godwits are long-lived migratory shorebirds with a typical lifespan of between 15 and 20 years. They nest in lowland wetlands dominated by grasses or by dwarf birch and sedges. They hide their nests, which means that they require sufficiently tall vegetation to conceal the nest and an incubating adult. Both vegetation growth and the timing of emergence of invertebrate prey for wader chicks are strongly temperature-dependent, particularly at high latitudes, which means that the timing of nesting and the growth-rate of chicks are likely to be influenced by local temperatures.

blog colonisationOver eight years, during which temperatures in Iceland varied substantially, José Alves and colleagues were able to quantify the influence of temperature on laying dates and the duration of the pre-fledging period of Icelandic godwits, and the subsequent influence of hatching dates on recruitment of chicks to the wintering or subsequent breeding population. The authors then used these relationships to model how the timing of breeding and the annual recruitment of juveniles into the breeding population may have contributed to population growth and the successful colonisation of new (and now warmer) parts of Iceland.

Catch your godwits

blog cr chickBlack-tailed Godwits are very good at hiding their nests and chicks! These three quotes from the paper help us to appreciate the effort that goes into establishing some of the key facts that underpin the modelling at the heart of this paper:

  • “Every nest was visited regularly and successful nests were revisited at the estimated hatching date, in order to capture and mark chicks and adults with individual combinations of colour-rings.”
  • “For each family, one of the adults was captured using either a nest-trap or a hand-held net-gun.”
  • “In 2012 and 2013, 32 godwit families were tracked during chick rearing, from hatching to fledging (n = 18) or brood loss (n = 14).”

Away from the main study area, volunteer ringers, led by Pete Potts of Farlington Ringing Group, caught, measured and colour-ringed chicks, thereby providing an assessment of hatching dates of chicks in other parts of Iceland.

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The assessment of which chicks subsequently survived and recruited into the adult population relied heavily upon the observations of hundreds of birdwatchers, throughout Western Europe, who take the time and trouble to report sightings of colour-ringed birds. Examples of their dedication and links to other papers that rely upon their efforts can be found in Godwits and Godwiteers.

Major Findings

Effect of temperature on timing of breeding season events: In Icelandic godwits, mean laying dates were approximately 11 days earlier in the warmest of years than in the coldest (two-degrees Celsius lower). This earlier start to the breeding season is thought to be linked to faster vegetation growth in warmer springs. The lengths of the chick pre-fledging period varied by only about 3.6 days between the warmest and coldest years but this additional difference means that fledging can happen a fortnight earlier in the warmest of years. 

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blog juv flocksProbability of recruitment: Early-hatched chicks are more likely to survive and recruit into the adult population, and the 11-day advance in hatch dates in warm years equates to an increase in absolute recruitment probability of about 10%. The additional benefits of more rapid chick growth and fledging in warmer years probably further increases this differential. In cold years, when most nests are laid late, very few chicks are likely to recruit to the adult population. For example, in 2011, the coldest year recorded during the study, only about 16% of 118 ringed chicks recruited into the wintering population. Early-fledged chicks presumably have more time to improve body condition prior to migration, there is an increased probability of travelling in adult-dominated migratory flocks (see graphic from Gunnarsson 2006), and earlier departure for wintering areas may allow more time in which to find a favourable wintering location.

blog big chickRegional variation: Traditional breeding sites are warmer, and so nests are likely to be earlier and incubation shorter, which means that more of the chicks from these areas are likely to survive and recruit into the population. The range expansion in this system could therefore have been driven by increased productivity and dispersal from traditionally colonised areas, supplemented by increased productivity within newly colonised – and now warmer – areas. Given the high levels of natal philopatry in Black-tailed Godwits (WaderTales blog about philopatry), the authors suggest that improved breeding conditions, following colonisation of new areas, have fuelled local population increases and further range expansion.

Are these findings applicable to other species?

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Sightings of colour-ringed juveniles, such as this one in eastern England, helped to establish recruitment rates.

The authors of this paper have been studying a species breeding at the northern limit of its range, in a country that has been subject to rapid climate change and in which there are relatively large differences in temperatures over quite small distances. This provides an ideal gradient over which to study change. Also, and unusually, it was possible to measure recruitment of chicks from right across Iceland, because of the colour-ring reports from observers. This set of circumstances have combined to enable the team to show that warming trends have the potential to fuel substantial increases in recruitment throughout Iceland, and thus to have contributed to local population growth and expansion across the breeding range. They propose that the same factors may be harder to tease apart for other species, in different environments, but that advances in lay dates and increased recruitment associated with early hatching may be key processes that drive population and range changes in migratory systems.

Paper

Linking warming effects on phenology, demography and range expansion in a migratory bird population. José A. Alves, Tómas G. Gunnarsson, William J. Sutherland, Peter M. Potts & Jennifer A. Gill.

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Juveniles gather together in the late summer, prior to departure


GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.

 

In search of Steppe Whimbrel

blog in flightIt’s unsurprising if you have not heard of a Steppe Whimbrel; the subspecies was declared extinct in 1994. In this context, a new paper in Wader Study, based on detailed studies of two birds that were found in Mozambique in 2016, adds immensely to our knowledge.

Bleak times for the Numeniini

The curlew family is facing huge pressures across the globe. Eskimo Curlew and Slender-billed Curlew are either extinct or close to extinction, with no confirmed sightings for 56 and 18 years, respectively. We are definitely losing species but are we losing diversity within individual species too – as suggested by the rarity of the Steppe Whimbrel and the fragmenting distribution of the Hudsonian Godwit? There is a lot of information about the current status of different populations and subspecies of the Numeniini  family in Why are we losing our large waders? a WaderTales blog about curlews, godwits and the Upland Sandpiper based on a review paper by James Pierce-Higgins and colleagues.

As a species, the Whimbrel is categorised as ‘of least concern’ but the ‘once extinct’ Steppe Whimbrel would be considered as ‘critically endangered’ if it were to be a species, rather than a subspecies.

Whimbrel are circumpolar in distribution and it is generally accepted that there are four subspecies:

  • phaeopus breed from Iceland through Scandinavia and into western Siberia; they spend the non-breeding season largely in western and southern Africa.
  • variegatus breed across the rest of north-eastern Russia and migrate to southeast Asia and Australia.
  • hudsonicus breed across northern Canada and Alaska and migrate to Latin America.
  • alboaxillaris are thought only to breed in the steppes of Russia and Kazakhstan, at the centre of the European land-mass, and to winter only in southeast Africa.

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First find (and identify) a Steppe Whimbrel

The fact that Steppe Whimbrel was considered to be extinct just 25 years ago gives a clue as to how hard it is to find one. Details about recent records are summarised in a new paper in Wader Study by Gary Allport and colleagues, that forms the basis of this WaderTales blog. Three breeding sites have been identified, holding a maximum of 19 breeding pairs, in total, and a maximum autumn count of 11 birds has been recorded on passage, on the shores of the Caspian Sea in 2010. The two birds that Gary found in Maputo, Mozambique in February 2016 are the first wintering records in Africa (or anywhere else) since 1965.

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The photographs above show that the two birds found at Maputo by Gary Allport of BirdLife International are different in several respects to the phaeopus with which they associated:blog on ground

  • Steppe Whimbrel are bigger
  • There are cleaner/paler in overall appearance
  • The rump is paler
  • They have white axillaries

For more information see Allport, G. & C. Cohen. 2016. Finding Steppe Whimbrel: discovery and identification in southern Africa. AfricanBirdlife 4: 48–54. If you come across what you think is a Steppe Whimbrel, possibly in eastern Africa during the non-breeding season, check for white under-wings and take as many pictures as possible!

blog in handAt the time of the discovery of the two Steppe Whimbrels, BirdLife had already got a strategy in place to deal with the unexpected appearance of a Slender-billed Curlew – ever hopeful that this species is not extinct. If seen in the non-breeding season, a bird was to be caught and satellite-tagged, in order to try to find its breeding area. The same procedures seemed appropriate for the Maputo Steppe Whimbrels and one bird was duly caught and tagged. That’s probably another story – anticipation – tension – concern for the bird’s safety – relief when it accepted its tag and behaved normally – and elation when data started coming in.

Local movements

blog photographerThe Maputo area, in which the two Steppe Whimbrel were found, comprises about 6 km of tidal muddy sand banks and flats. The area is heavily used by people, with zoned sections for various uses including traditional worship and tourism. The two Steppe Whimbrel were found by chance in February 2016, at the high tide roost on the upper beach. One was bigger than the other, suggesting a female and male. No other alboaxillaris were found in a larger population of 650 Whimbrel photo-identified in Maputo Bay. This paper talks about the discovery: Allport, G. 2017. Steppe Whimbrels Numenius phaeopus alboaxillaris at Maputo, Mozambique, in February–March 2016, with a review of the status of the taxon. Bulletin African Bird Club 24: 27–37.

The local movements of the two Steppe Whimbrel in Maputo Bay, Mozambique, were studied opportunistically from February to March 2016. Both birds were found to be part of a local sub-population of ca. 30 Whimbrel which held individual feeding territories on sandy shorelines. There are important details about behaviour and habitat-use in the Wader Study paper. The male was seen more frequently and predictably.  Knowledge of his movements made it possible to catch him, by dazzle-netting at night, on 6 March. Metal and colour-rings were added, together with a PTT satellite tag. A DNA sample proved that he was indeed a male.

The male was noticeably plump when caught, suggesting that he was already preparing for northward migration. Data gathered from the tag during the period before departure added valuable extra information about key feeding areas north of the main study area, where mangroves make it hard to observe birds.

Time to fly north

blog mapThe female Steppe Whimbrel was last seen in the Maputo area on 28 February 2016, and it is suggested that she may have left the areas on or shortly after this date. The last sighting of the male was on 24 March 2016 and, using information from his PTT satellite tag, the Mozambique team know that he started to migrate the next day. Although nearly a month after the possible departure of the female, this is still one month earlier than the onset of migration for the phaeopus subspecies. This is not unexpected; phaeopus birds are heading for higher latitudes than alboaxillaris, which breed in the heart of the Eurasian continent, in the steppes of Asia.

Upon leaving Mozambique, the tagged male headed over Tanzania before the scheduled transmission phase ended. At the start of the next recording period, the bird had travelled to the northern end of the Great Rift Valley in Ethiopia. He then turned in a more easterly route to the Somali coast. During the tag’s next ‘off phase’ he crossed the Gulf of Aden where he was picked up moving up and down the coast before settling on some salt-pans in the area of Little Aden.

The tagged bird made a 4,659-km journey in six days to Aden, Yemen and his migration route was consistent with the direction of travel for the known breeding areas of alboaxillaris. The track data are the first firm evidence of a long-suspected African transcontinental migration route for southeastern Afro-Palaearctic coastal waders.

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The tag was attached to the back of the Steppe Whimbrel. Feathers have been parted to show the  tag. After two months, the tag dropped off.

The tagged Steppe Whimbrel stayed in the Little Aden coastal area of Yemen until 10 May, when the pattern of fixes changed to a stationary location in the northwest side of the bay. This suggested that the tag had fallen off the bird, possibly floated across the bay on the prevailing southeast wind and then settled on the shoreline. Confirmation of the loss of the tag came on 14 August, when Gary Allport came across the same Steppe Whimbrel, wearing colour rings, back in Maputo. That must have been a great moment.

Key take-home messages

tweet 4If you are on the African shores of the Indian Ocean, in Africa’s Great Rift Valley or perhaps the coasts of western India or the Middle East, please check out any Whimbrel you see. Steppe Whimbrels live up to their names – look out for the white (albo) underwing (axillaris). Perhaps you will find the next Steppe Whimbrel and it will be in a location where capture is again possible. Maybe your bird will carry the next PTT transmitter for long enough to tell conservationists where to look for what must be a tiny population of breeding Steppe Whimbrel. Peter Ryan of the Percy Fitzpatrick Institute of African Ornithology (University of Cape Town), has recently secured funding from the Mohamed Bin Zayed Fund to tag Steppe Whimbrel. He and Gary are on the look-out for any birds that might be suitable for further study. 

blog in hand underwingOne of the great things about this tracking study is that it acts as a trial-run, should anyone find a Slender-billed Curlew or (even more unlikely) an Eskimo Curlew. We know that BirdLife scientists and their colleagues have the skills needed safely  to catch a rare, large wader and to maximise the amount of information that can be gathered about its migratory movements. Fingers crossed that it’s not too late to find out what is happening to other Steppe Whimbrel, or possibly even Slender-billed Curlew. Sadly, I think that we have to admit that the Eskimo Curlew is now almost certainly extinct.

Paper

Click on the paper details below to link to the Wader Study website. Full text is only available to members of the International Wader Study Group.

Allport, G.A., P.W. Atkinson, M. Carvalho, N.A. Clark & R.E. Green. Local site use and first northbound migration track of non-breeding Steppe Whimbrel Numenius phaeopus alboaxillaris (Lowe 1921). Wader Study 125(3). doi:10.18194/ws.00126

 

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GFA in Iceland

Graham (@grahamfappleton) has studied waders for over 40 years and is currently involved in wader research in the UK and in Iceland.  He was Director of Communications at The British Trust for Ornithology until 2013 and is now a freelance writer and broadcaster.