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.

blog wide expanse


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 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?

blog migration map

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.

 

Designing wader landscapes

blog whimbrelMuch has been written about the negative impacts of agriculture on breeding birds – but farming can be good for some species. In Iceland, where high-input agriculture is relatively recent, breeding waders are commonly found in nutrient-rich environments that are associated with increased production. How can high breeding densities of waders be maintained, as farming continues to expand and intensification increases?

In her paper in Agriculture, Ecosystems & Environment Lilja Jóhannesdóttir investigates the distribution of breeding waders across landscapes with varying amounts of highly-cultivated fields and semi-natural areas. She discovers that, in some circumstances and at an appropriate level, adding cultivated land within a broader mosaic of habitats may benefit breeding waders. Is this a model system that provides clues as to how to design landscapes that can support sustainable breeding wader populations in other parts of the world?

The waders of Iceland

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Breeding populations of waders in Iceland (AEWA report)

Iceland is a hot-spot for breeding waders, holding half or more of Europe’s Dunlin, Golden Plover and Whimbrel, in a country that is a bit smaller then England. The paper at the heart of this blog is written by Lilja Jóhannesdóttir, who worked with colleagues from the University of Iceland, the Agricultural University of Iceland, the University of East Anglia (UK) and the University of Aveiro (Portugal). They investigated how different ways of increasing agricultural productivity might impact upon these species, and others such as Black-tailed Godwit, Redshank and Snipe.

Much of Iceland’s upland interior is not suitable as farmland but there is still plenty of room for agricultural expansion. Only 7% of the area between sea level and an elevation of 200 m is currently under cultivation but it is estimated that it would be possible to increase this to 63% – an eight-fold extensification. Icelandic lowlands currently comprise a fine-scale mosaic of open semi-natural habitats and cultivated fields (primarily for silage production to feed animals), making most of the landscape much more heterogeneous than in countries with a longer history of commercial farming.

blog hay and semi-naturalTwo previous WaderTales blogs have already shown that:

Given that farm production is predicted to increase, that farmers like breeding waders and that some intensively-managed fields can be attractive to waders, is it possible to design farmed landscapes that will work for birds and farmers?

Increasing inputs and reducing heterogeneity

blog nice wetlandGlobally, the expansion and intensification of agriculture has altered landscapes and the associated homogenisation has greatly influenced bird abundance and reduced biodiversity. Populations of numerous species, particularly specialist species, have declined, as agriculture has expanded, while generalist species have often thrived in agricultural habitats.

There is no shortage of examples in which highly intensively managed farmland is shown to be bad for breeding waders. In the monoculture hay-meadows of the Netherlands, Black-tailed Godwit productivity is really low, for instance. These fields have been drained, fertilised and re-sown, in order to create easily-managed carpets of single-species grass that can be cut several times a year. There is more about this in this paper by Roos Kentie.

blog hay fieldAlthough there are some areas of Iceland in which farming is quite intensive, there are many others where farmers have a lighter touch. For instance, nutrient-poor dwarf birch marshes may occasionally be grazed by sheep in the summer but these areas have never received applications of artificial fertiliser. At this end of the intensification continuum, increasing agricultural operations may have benefits for breeding waders. When a patch of rough grazing is ploughed and turned into a hay meadow, the addition of fertilisers can potentially increase soil fertility and create an attractive place for waders to feed. A hay meadow within a local area that is dominated by dwarf birch marsh could effectively increase the heterogeneity (& nutrient-richness via spill-over) of the local area, albeit in an artificial way. In the UK, Golden Plovers breeding on moorland are known to travel up to 7 km to feed on fertilised hayfields with high earthworm densities. This paper by James Pearce-Higgins & Derek Yalden in IBIS provides a nice example of how low intensity agriculture can provide resources for waders in the wider landscape.

Researching waders and landscapes

blog dbmLilja’s work in the Southern Lowlands of Iceland focused upon understanding how agriculture influences breeding wader densities and how these relationships might influence future change. At its heart were counts of adult waders encountered along 200 transects (totalling over 100 kilometres) within semi-natural habitats, visited at several stages during the breeding seasons of 2011 and 2012.

As well as counting birds, Lilja categorised habitats within 500, 1000, 1500 and 2500 metres of the transects, which she called buffer area in the paper. Interestingly, and usefully for later analyses, the distribution of different habitat types is pretty uniform across these scales, in this part of Iceland, with little substantial difference according to elevation. In the diagram below, the 200 transects (a) have been split between those below 50 m above sea level (b) and those higher than 50 m (c).

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Landscape-scale effects

To fulfill the various demands of parents and their offspring, waders need diverse resources on or near their territory. An adult can feed a kilometre or more away from its nest, between incubation bouts, and chicks are mobile from an early age. Tagging has shown that young Black-tailed Godwits can move up to 3 km in the first five days of life, just to give one example. In this open landscape, breeding success is likely to be a function of habitat availability at a broad scale. This is explored in a WaderTales blog about nesting Whimbrel.

blog redshankUsing data collected from these 200 lowland transects, Lilja was able to establish relationships between breeding wader densities and the amount of cultivated land and wetland in the surrounding landscape. These two habitat types were considered because future agricultural expansion is likely to take place on drained wetlands that have high conservation value. In her analyses she assessed the extent to which the amount of cultivated land in the surrounding landscape affects wader densities on semi-natural land, and then considered the potential effects of future agricultural expansion on wader populations. There was substantial variation in the density of all of the six most common wader species recorded on the transects, ranging from 0 to 284 birds/km2.

Lilja found that wader densities in semi-natural habitats were consistently greater when the surrounding landscapes had more wetland, at scales ranging from 500 m to 2500 m, indicating the importance of wetland availability in the local neighbourhood. However, the effects of cultivated land in the surrounding landscape varied with fertility and landscape structure, which was largely defined by altitude.

  • In fertile, low-lying coastal areas (from sea-level to 100 m altitude), wader numbers declined with increasing amounts of cultivated land (and the lowest densities occurred in areas dominated by cultivation). This suggests that further conversion of semi-natural habitats into farmland is likely to severely impact waders in low-lying areas.
  • In less fertile habitats at higher altitudes (between 100 m and 200 m), the lowest densities occurred in areas without cultivated land. This suggests that additional resources provided by cultivated land may have a more positive affect in the less-fertile, higher altitude areas.

blog blackwitThe relationships between the areas of wetland and agriculture in the surrounding landscape and the density of waders vary between species, as you can read in some detail in the paper. A few highlights are:

  • With increasing area of cultivated land, densities of Golden Plover, Dunlin and Whimbrel declined significantly at lower altitudes but increased at higher altitudes. These are the three species that would appear to respond most positively to the addition of pockets of cultivated land within a semi-natural matrix of less fertile land, that tends to be found at higher elevations.
  • Higher amounts of wetland were associated with increased densities of Dunlin and Black-tailed Godwit, but lower densities of Redshank. Golden Plover numbers were unaffected by amount of wetland in the surrounding landscape.
  • Whimbrel densities increased with wetland area, at higher altitudes. Wet patches have been shown to be very important to Whimbrel chicks, as you can read in this WaderTales blog about research in Shetland.
  • At lower altitudes, Snipe densities increased with the amount of wetland area in the local vicinity. This relationship was less pronounced at higher altitudes, which tend to be less effectively drained and hence generally wetter.

dunlin graphic

What now?

Changes in Icelandic landscapes are to be expected in the coming years, as most farmers intend to increase their areas of cultivated land. This expansion will inevitably have impacts upon the internationally important breeding wader populations of Iceland but the level of such impact will depend on where the expansion will occur. This paper shows that increases in the area of cultivated land at lower altitudes in Southern Iceland are more likely to result in declines in wader density than in less fertile areas, when tend to occur at slightly higher altitudes (still under 200 m above sea level). An important next step will be to identify the landscape structures and scales of management that can continue to support high densities of breeding waders.

blog coastal wetlandGiven the international importance of Iceland as a home for breeding waders it would be nice to think that this paper can be used to develop national land management policies that can prevent the unintended loss of species such as Golden Plover and Snipe, which landowners value and wish to preserve. At the farm and community level, the paper highlights the key importance of maintaining the complex and heterogeneous landscapes of lowland Iceland, retaining as many as possible of the remaining wetland patches and pockets of semi-natural land within even the most intensive of farming areas.

The paper may well be of interest to conservationists who are struggling to reverse wader declines in other parts of the world. In Southern Iceland, where 7% of the land is being farmed relatively intensively within a fine scale mosaic of both wet and dry semi-natural habitats, it is possible to support hundreds of waders per square km across the wider countryside. Can this situation be replicated across large tracts of land in other countries?

Take home message and paper

blog heterogeneousThis paper provides a useful reminder that the links between land use changes and biodiversity implications can be highly context-dependent. Further agricultural conversion of wetlands and rough grazing areas in the fertile low-lying areas of Iceland is likely to be detrimental for breeding waders, but such effects may be less apparent in less fertile, higher altitude areas. Here, the conversion of some land from rough-grazing to hay meadows may provide feeding opportunities off-territory for Dunlin, Golden Plover and Whimbrel. The scale at which the addition of cultivated areas is beneficial to breeding waders has yet to be determined.

This paper is published as:

Interacting effects of agriculture and landscape on breeding wader populations. Lilja Jóhannesdóttir, Jennifer A. Gill, José A. Alves, Sigmundur H. Brink, Ólafur Arnalds, Verónica Méndez and Tómas Grétar Gunnarsson https://doi.org/10.1016/j.agee.2018.11.024

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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.

 

Leg-flags and nest success

For ornithologists studying birds by adding colour-rings, flags and tracking devices, a question of fundamental importance is always “am I affecting the birds’ survival or behaviour by requiring them to carry these markers?” This is not just a welfare issue; if marking birds affects the way that birds behave or changes their chance of survival then any findings are dubious. In a paper in Journal of Field Ornithology, Emily Weiser explores whether leg flags influence the nesting success of four species of small wader (shorebird).

Using leg-flags

Western Emily

Western Sandpiper

Rings rarely have any negative effects on birds and are frequently used to mark individuals. Leg flags are bigger and easier to see, and there is space to add letters/numbers, but they are also bulkier and heavier. Might there be a consequence of flag-wearing for the nesting success or survival of individuals? By analysing nesting-success data collected at seven sites in Arctic Alaska and western Canada, Emily Weiser and colleagues were able to check for flag effects on four species of Arctic-breeding shorebird: Semipalmated and Western Sandpipers and Red-necked and Grey (Red) Phalaropes. The study involved measuring daily survival rates for nearly 2000 nests – which is a huge sample size. The amount of work involved is reflected in the fact that the Weiser paper has 24 authors!

flagged in handA flag is a plastic strip shaped to wrap around a bird’s leg. It is like a colour-ring but with a tab that extends from the leg, increasing its conspicuousness and providing an opportunity to inscribe a letter/number code. The probability of generating individual sightings can be increased but at what costs? Might flags make nesting birds more obvious to predators? Could the bulkier flag damage the eggs? Might the flag affect incubation efficiency? Whilst it was not possible to answer each of these questions separately, the total effect could be measured by checking to see if nest survival was different for birds wearing flags, as opposed to rings.

Findings

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Male Red-necked Phalarope

Between 205 and 780 nests of the four species of Arctic-breeding shorebirds were included in the study, with between 36% and 82% of these nests having at least one adult with a leg flag in attendance. For the two sandpipers (Western and Semipalmated), the sample included nests with two flagged parents, about half as many where only one parent had a flag and others where parents wore colour-rings (bands), rather than flags. Female phalaropes do not brood their eggs so, for Red-necked and Grey (Red) Phalaropes, nests were categorised by whether males wore flags, or just colour-rings. Several different analyses were carried out, to take account of the number of flagged parents, year effects etc., as you can read in the paper, but there is one key result; there is no evidence that leg flags affect the daily survival rate (DSR) of the nests for any of the four species, or the probability that a nest is successful (see figure).

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Across the whole incubation period, the proportion of nests expected to hatch did not differ between nests with or without flagged adults. There was variation between species, with the estimated probability of eggs hatching varying from 70% for Western Sandpiper to 91% for Grey (Red) Phalarope. These figures are higher than reported previously because the analysis was only for nests where at least one bird was captured. Early failures were therefore excluded. Overall nest success rates are reported in this paper.

A mix of species

Banded RNP

Colour-ringed Red-necked Phalarope

This study focused on four small species of wader, from Semipalmated Sandpiper (26g) to Grey (Red) Phalarope (49g), in which any effects of (relatively large) flags on breeding success might be expected to be higher than for larger species of wader. The results are very similar, despite the fact that sandpipers and phalaropes differ in two potentially important ways:

  • The species behave very differently, using very different feeding methods – phalaropes feed mainly on water, while the two sandpipers feed on land and at the land-water interface
  • In sandpipers, both parents attend the nest but in phalaropes only one parent (the male) attends the nest.

Could flags have other effects?

Semi Emily

Flagged Semipalmated Sandpiper

Nothing in the data analysed for this paper suggests that flags are affecting survival rates of marked birds during the period when birds are breeding. The authors suggest that it would be useful to undertake further analyses to check:

  • Nest survival rates for a broader range of species and in different habitats (where, for instance, predators might behave differently).
  • Growth rates of chicks wearing flags and of chicks being cared for by parents wearing flags.
  • Annual survival rates of adults and chicks that wear flags.

Emily Weiser has also written a review of the effects of leg-mounted geolocators on waders/shorebirds. Here she found that there could be problems in a small number of circumstances. This important paper is summarised in this blog: Are there costs to wearing geolocators?

Another WaderTales blog examines the preening and feeding behaviour of Green Sandpipers that wear geolocators attached to harnesses.

More in the paper

Emily in field

Emily Weiser in the field

Any researchers who wish to investigate the effects of marking birds will find it useful to read the whole paper, for details of methods and analyses. There is also a long list of references relating to the effects of marking birds. Information about the particular types of flags used in these studies may also be  helpful.

Effects of leg flags on nest survival of four species of Arctic-breeding shorebirds: Emily L. Weiser, Richard B. Lanctot, Stephen C. Brown, H. River Gates, Rebecca L. Bentzen, Megan L. Boldenow, Jenny A. Cunningham, Andrew Doll, Tyrone F. Donnelly, Willow B. English, Samantha E. Franks, Kirsten Grond, Patrick Herzog, Brooke L. Hill, Steve Kendall, Eunbi Kwon, David B. Lank, Joseph R. Liebezeit, Jennie Rausch, Sarah T. Saalfeld, Audrey R. Taylor, David J. Ward, Paul F. Woodard and Brett K. Sandercock Field Ornithol. 89(3):287–297, 2018 DOI: 10.1111/jofo.12264

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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.

Deterring birds of prey

What conservation solutions are available if a protected bird of prey is feeding on the chicks of red-listed colonial or semi-colonial waders/shorebirds? A new paper (which actually focuses on amber-listed Little Terns) may well be of interest to conservation practitioners and research ecologists.

Threats to young chicks

blog Tern and KestrelPredation can limit bird populations, especially in ground-nesting and colonial species. In the UK, non-native mink can be trapped, foxes can be shot and badgers can be kept away using fences – but what can you do if a Kestrel is eating your Little Tern chicks? That’s the subject of a new paper by Dr Jen Smart (RSPB) and Dr Arjun Amar (RSPB & Fitzpatrick Institute of African Ornithology, University of Cape Town).

Diversionary Feeding

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Christened ‘Morticia’, this female Kestrel acquired a taste for Little Tern chicks

One potential solution in a predator/prey conflict situation is to use Diversionary Feeding – providing prey items that are easier to collect than wader or tern chicks. In their paper in the Journal for Nature Conservation, Jen Smart and Arjun Amar test the efficacy of this solution. In this example, the prey items were Little Tern chicks and the predators were a small number of nesting Kestrels but the same situation could arise on a beach with nesting Ringed Plover, on an island with nesting Avocets or on a wet grassland with semi-colonial Lapwings.

Over a seventeen-year period, teams of RSPB staff and volunteers have been trying to help Little Terns nesting in Great Yarmouth, Norfolk. It’s an internationally important colony of up to 369 pairs, which is equivalent to about a quarter of the UK population. It is also close to a local conurbation, with generalist predators such as foxes, cats, crows and gulls, on a beach that is a favourite with dog-walkers.

blog colonyElectric fences and friendly wardens can keep most people and animals away but birds are still a problem, especially a small number of Kestrels that have learnt that the tern colony is a great feeding area. In six of the 17 years, feeding stations were set up close to Kestrel nests, to try to reduce the impact of Kestrels on the Little Terns. In four years (two with Diversionary Feeding and two without) there was intensive monitoring of the Kestrels’ feeding behaviour, to ascertain how their diet changed when alternative food was supplied.

Does Diversionary Feeding work?

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Poultry chick being delivered

In the Great Yarmouth Little Tern colony, predation by Kestrels has been a serious issue. Over the whole 17-year study period, at least 3436 Little Tern chicks were taken by Kestrels and, to put this in context, only 2536 chicks fledged.

In the face of this challenging situation, providing food very close to the nest sites of individual Kestrels that were known to focus their attention on the Little Tern colony has been remarkably successful.

The key results from the paper are:

  • Predation levels were 47% lower and productivity of Little Terns almost doubled in years when Kestrels were fed.
  • During the four years of intensive monitoring, predation rates were eight times as high when diversionary feeding was not employed. This equates to 9.1 Little Tern chicks per day, as opposed to 1.1 chicks per day.
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    Wild prey – a vole this time

    Providing alternative prey, in the form of surplus day-old poultry chicks and laboratory mice, not only reduced the impact on Little Terns; it reduced predation of other local wildlife. By observing the prey that was delivered to the nest, over the course of four breeding seasons, the research team found that 3.4 times as many items of wild prey were presented to Kestrel chicks in the two years when alternative food was not provided, compared to the years with Diversionary Feeding.

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    Little Tern chick

    The researchers note that, by counting prey items provided to Kestrel chicks, they are ignoring the tern chicks that will have been consumed by adults. They suggest that young tern chicks were treated as ‘snacks’ for adults, possibly because they were too small to be worth transporting back to the nest. They estimate that 20% of the artificial food supplied to the Kestrels may have been eaten by the adults.

  • The cost of supplying food to the Kestrels was between £100 and £200 per nest. The cost of employing a research assistant to find, feed and monitor nests was £12,000. Now, having proved that Diversionary Feeding works, it would be possible to significantly reduce staff time, because the intensive monitoring undertaken as part of this study would only be necessary for a short time, to ensure any fed kestrels were responding positively to the food provided.
  • blog graphThere is a large amount of detail in the paper about the specifics of Diversionary Feeding in this situation. Supplementary materials provide details about the timing of predation events across the day and information about how much food per day was supplied to the Kestrels, over the course of the breeding season.

A growing problem?

As the number of breeding birds in the wider countryside has declined, hot-spots such as nature reserves have attracted the attention of predators. Providing increased areas of suitable habitat for species such as Marsh Harriers and Bitterns, reintroducing species (e.g. Red Kite) and providing nest sites (e.g. Peregrine) in areas that are close to key sites for colonial and semi-colonial waders (and terns) may well mean that we see more conflicts between pairs of avian predator and prey species, both parties of which are of conservation concern. In some cases, as for the Norfolk Kestrels, a small number of individuals learn to target areas in which there are high concentrations of young birds.

blog avocet kestrelThe authors point out that different predator-prey interactions may well require different conservation solutions. In the case of Kestrels, the adults were well able to dissuade scavengers from approaching the feeding sites, which were located close to their nests. In other situations, feeding sites could themselves attract predators, scavengers and vermin, especially if food supply is not regulated carefully. Any Diversionary Feeding measures will need to be thoughtfully monitored to check for unintended consequences.

blog red kiteDiversionary Feeding may well be an important tool to use in specific circumstances; it’s already used by the RSPB to deter Red Kites preying on Lapwings at a nature reserve in Oxfordshire, for instance. Conservation practitioners and research scientists will find it useful to read the whole paper. If Diversionary Feeding is employed, then it seems sensible to develop protocols to test whether it works in different predator-prey systems and to report back on the outcomes.

Paper

This work is published as: Diversionary feeding as a means of reducing raptor predation at seabird breeding colonies Jennifer Smart and Arjun Amar, Journal for Nature Conservation, https://doi.org/10.1016/j.jnc.2018.09.003

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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.