Scottish Wader Woes

The latest report on Scotland’s terrestrial bird species, covering the period 1994-2016, does not make easy reading for wader lovers. All but one species is contributing negatively to the upland bird indicator, with declines of over 40% for breeding Lapwing, Curlew, Dotterel, Oystercatcher and Golden Plover. In this short blog, there are links to information that helps to explain what might be going wrong for Scotland’s waders.

The full report is available on the SNH website (https://www.nature.scot/information-library-data-and-research/official-statistics/official-statistics-terrestrial-breeding-birds)

One species has been increasing – Snipe up 22%

snipe abundance changeThe one spot of good news is that breeding Snipe numbers in Scotland have risen over the period 1994 to 2016. This is particularly encouraging, given declines in much of the rest of Britain and Ireland, as you can see in the map alongside and read in this WaderTales blog Snipe and Jack Snipe in the UK and Ireland.

In the map, produced for Bird Atlas 2007-11 (BTO, BirdWatch Ireland & SOC), pink colours show abundance increases and grey areas show decreases.

Lapwing declines largest – down 63%

GHH pictureWhen a widespread species such as Lapwing is in decline this is bad news. Subtle difference in the way that lowland valleys are farmed may be part of the problem, as illustrated in this WaderTales blog based on work by Mike Bell, written up with the help of John Calladine, of BTO Scotland: 25 years of wader declines.

Curlew down 62%

Blog Jill PThe Curlew is causing huge concerns in Ireland and Wales, where conservationists are contemplating its disappearance as a breeding species. Scotland holds much larger numbers but a decline of nearly two-thirds suggests that there are major problems here as well.

Two WaderTales blogs tell the Curlew story. Is the Curlew really near-threatened explains why we should be so worried about what is happening and Curlews can’t wait for a treatment plan summarises a BTO-led paper from Sam Franks and colleagues which attempts to explain the patterns we are seeing in the species’ decline.

Dotterel down 60%

IMG_2123

Alistair Baxter

Most of the information about Scotland’s breeding birds comes from annual data collected by volunteers contributing to the Breeding Bird Survey (BBS), organised by the BTO, in partnership with JNCC and RSPB. Dotterel is different; here the counts are dependent on dedicated surveys of Scotland’s high-mountain plateaus. Concern for the species is very much linked to climate change but this blog, based on a paper by the RSPB’s Daniel Hayhow and colleagues, shows that there may well be other reasons for the species decline: UK Dotterel numbers have fallen by 57%. The figure for the decline may be slightly out-of-date but the blog isn’t.

TGG OycOystercatcher down 44%

In England, the latest BBS report shows an increase of 50% in Oystercatcher numbers but, in Scotland, where there are far more breeding pairs, the species is in decline. Oystercatchers: from shingle beaches to roof-tops looks at the history of the species’ spread from the shoreline, into the hills and onto roofs and considers the role of predation in recent declines.

Golden Plover down 43%

As noted in the press release about the new report ‘The golden plover population has declined by 43% since 1994 and stands at its lowest point since the BBS survey began. Declines may be linked to climate change, in part due to impacts on the abundance of craneflies during the breeding season’. There are two interesting papers about this by James Pearce-Higgins and colleagues.

golden ploverPearce-Higgins, J.W., Yalden, D.W. & Whittingham, M.J. 2005. Warmer springs advance the breeding phenology of golden plovers Pluvialis apricaria and their prey (Tipulidae). Oecologia 143: 470–476.

Pearce-Higgins, J.W., Dennis, P., Whittingham, M.J. & Yalden, D.W. 2010 Impacts of climate on prey abundance account for fluctuations in a population of a northern wader at the southern edge of its range. Global Change Biology 16: 12–23.

Common Sandpiper down 39%

The Breeding Bird Survey does not properly capture trends for species found mostly along rivers. Data for Common Sandpiper are derived from the BTO Waterways Bird Survey and the Waterways Breeding Bird Survey.

Why no Redshank?

Unfortunately, breeding Redshank are now patchily distributed across Scotland, with too few being picked up by BBS surveyors to make a contribution to Scottish population indices. Across the UK, the latest published BBS decline is 38%. UK graphs for Oystercatcher, Redshank and Curlew are shown below.

UK BBS


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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Well-travelled Ringed Plovers

Waders breeding in Chukotka, in the north-east corner of Russia, have a long way to travel at the end of the summer, in search of suitable habitats in which to spend the non-breeding season. A new study, using geolocators, shows that Ringed Plovers from this area fly between 8,900 and 12,100 km each autumn and in a very different direction to most other shorebirds that breed in the same area.

RP no geolocatorThis blog is based on a new paper in Wader Study, written by a team led by Pavel Tomkovich of the Moscow Zoological Museum. Their study describes the seasonal movements of tundrae Ringed Plovers from the easternmost edge of the subspecies’ distribution.

Pavel and his colleagues work in the south-eastern part of Chukotka, the region of Russia that is bounded by the Pacific Ocean to the east and the Arctic Ocean to the north. The data used in the paper were collected from five males that carried geolocators on their journeys to and from their wintering locations. Incredibly, during the mid-winter period, the birds were scattered from the Persian Gulf to the Nile Delta and south to Somalia, all of which are a very long way from Chukotka.

Range and distribution

RP snowy welcoms.jpg

Scene awaiting Ringed Plovers arrive in Chukotka in spring

Ringed Plovers breed over much of the Arctic region, from Greenland (and the eastern fringe of the northern Canadian islands), eastwards through northern Norway and right the way across Russia to the far eastern corner of Chukotka. The missing piece of the Arctic, between Newfoundland in eastern Canada and the western islands of Alaska, is the home of the very similar Semipalmated Plover. Additionally, there is a latitudinal spread in Ringed Plovers, with pairs in Europe breeding from Iceland throught to France.

Ringed Plovers breeding in the west

TTFReaders in Britain & Ireland will see Ringed Plovers in every month of the year. A colour-ringing study in Norfolk showed that many marked birds remained near their breeding sites for the whole year, while others migrated in a variety of directions in the autumn, exemplified by individuals flying south to France, north to Scotland and west to Ireland. In the spring, we see a strong passage of birds that have been wintering in countries in western Africa and southern Europe. They are on their way to breeding areas in Canada, Greenland and Iceland, in the west, and (to a lesser extent) Scandinavia in the north.

Ringed Plovers breeding in the north and east

Ringed Plovers breeding along the Arctic coastal fringe of Russia were believed to winter in eastern and southern Africa, right down to the southern tip of the continent. This new study, written up in Wader Study, the journal of the International Wader Study Group, is the first to reveal the migration routes of birds from the very far east of the range. The results are amazing, as illustrated by the map below which shows the movements of one male bird that wore a geolocator for a year. During that time he flew north-west to the Arctic coast of Siberia, south-west and south to Somalia, returning home through Siberia in the spring by a more southerly, inland route. His annual migrations totalled 25,000 km.

Global map

The migration route of one Ringed Plover. Map provided by Ron Porter

In the paper, the authors map and discuss the journeys of this Ringed Plover and four other males, in great detail. The ultimate winter destination of the birds that are not shown in this blog were the Nile Delta, the Persian Gulf (2) and the Red Sea. Unlike some other wader species, the migration strategy of Ringed Plovers is to use a wide range of suitable wetlands (often small and temporary) for only brief stops. It is unusual to see large flocks; the only important staging area to be identified so far, across the whole of Asia, is in north-central Kazakhstan.

Global perspective

global illustrationChukotka attracts birds from across the world. As well as Ringed Plover that fly here to breed from North Africa and the Arabian Peninsula, there are Knot from Australia and New Zealand, Semipalmated Sandpipers from South or Central America and Spoon-billed Sandpipers from anywhere from India to China – just to select three species that share the tundra with Ringed Plovers. The diagram alongside hints at the many different directions in which birds depart at the end of the breeding season. It’s really quite amazing!

RP three spcies

The Chukotka melting-pot: Knot from Australasia, Semipalmated Sandpiper from the Americas and Spoon-billed Sandpiper from Asia.

Historical perspective

Most Chukotka waders follow the East Asian-Australasian Flyway and it may seem surprising that Ringed Plovers are so different. The authors suggest that bird migration routes repeat the direction of expansion of a species’ historical breeding range, which will have changed markedly since the last Ice Age. In the late Pleistocene, Ringed Plovers may have had a largely Western Palaearctic breeding distribution with migration south to Africa each autumn. As the ice melted, and large areas of suitable habitat became available, the breeding distribution may have expanded eastwards, with these eastern breeders continuing to winter in Africa but travelling a lot further in autumn and spring.

Read the full paper here

RP geolocatorTranscontinental pathways and seasonal movements of an Asian migrant, the Common Ringed Plover Charadrius hiaticula tundrae. Pavel S. Tomkovich, Ron Porter, Egor Y. Loktionov & Evgeny E. Syroechkovskiy. Wader Study 124(3)

Further Reading in WaderTales

If you would like to learn more about migration to, from and through Britain & Ireland, have a look at Which wader, when and why?

RP lesser sandplover

Lesser Sandplover is one of the Chukotka species that migrates via the Yellow Sea

Geolocators are providing new and important information about migration but they need to be used safely. There’s a review here that will be of interest to anyone who is thinking of attaching devices to birds: Are there costs to wearing a geolocator?

There is a lot of concern about species such as Knot and Spoon-billed Sandpiper that breed in Chukotka and rely upon resources in The Yellow Sea. Read more in Wader declines in the shrinking Yellow Sea.

 

RP habitat


 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

 

 

Waders are long-lived birds!

The BTO longevity record for a wader is held by an Oystercatcher that was ringed as a chick by Adrian Blackburn in Lincolnshire (east coast of England) on 14 June 1970 and last caught by the Wash Wader Ringing Group on 16 July 2010, in virtually the same bit of the county. The time between ringing and last capture was 40 years 1 month and 2 days. Perhaps the bird is still alive?

Redshank

Will this Redshank live for another 10, 20 or 30 years?

Just to put records for British & Irish waders into context, the record for seabirds was set by a Manx Shearwater, at 50 years 11 months and 21 days, for waterfowl it’s a Pink-footed Goose (28 years 7 months and 7 days) and the longevity record for a passerine was set by a Rook (22 years 11 months 0 days).

This blog summarises records from the BTO Ringing Scheme between 1909 and 2016. These longevity records might be useful for a bird club quiz but they tell us very little about the health of wader populations. The real thing that is of interest is survival rates. Measuring the proportion of adult birds that survive through until the next year turns out to be exceptionally important to our understanding of wader conservation. There will be more about this later.

Records from the BTO scheme

Table2The list of records alongside is taken from the Online Ringing Report, produced by the British Trust for Ornithology. (The link to the longevity records can be found at the bottom of the web-page). The report covers all birds ringed and/or reported in Britain & Ireland up until the end of 2016. I aim to update this blog shortly after each new annual report is published.

For each species, longevity is defined as the time between ringing and the most recent report of that bird. For a chick, this figure is virtually equivalent to age but a bird first ringed when already an adult may be many years older than the longevity figure. The third column is the number of birds ringed for each species (up to the end of 2016). Records for species of which fewer than 3000 individuals have been ringed are given in italics, to indicate that the small sample size might be affecting the longevity record. With fewer birds being handled, the chance of catching a bird that is going to live a long time is low, as is the chance of it being caught again many years later.

In common with most groups of birds, the longest-lived ones are the biggest. Only Oystercatchers, Curlews and Bar-tailed Godwits have so far broken the 30-year barrier. At the other end of the scale, for smaller species, only the Ringed Plover has reached 20 years.

_DSC4194b

Grit wears even the hardest of metal rings (Richard Chandler)

With the passage of time, two things get older, the bird and its ring (or three things, if you think about the age of the ringers). Early rings were made of alloys of aluminium and these deteriorated quite rapidly, especially in salt water. Many of these rings will have given up long before the birds that were ringed. The widespread introduction of harder alloys in the 1970s has helped to increase longevity records.

Species such as Turnstone still wear out their rings and the oldest Oystercatchers are often birds that have carried two or more rings during the course of their lives. Such replacements only take place in areas where long-term studies are taking place, as was the case for the 40-year-old Oystercatcher mentioned above. It was first ringed as SS58540 but also known as FC15938 and FP99170.

FrenchAnother factor affecting our ability to appreciate just how long a wader can live is the use of colour-rings. The record-breaking Black-tailed Godwit is currently EF90838. This bird was hatched from an egg in Iceland in 1977 and received a metal ring on 24 October that autumn, at Butley in Suffolk. Many east-coast Black-tailed Godwits moult on the Wash (between Lincolnshire and Norfolk) and this bird was caught there in 1993. Already 16 years-old, it received two colour-rings that identified it as a bird taking part in a new Wash-based study, but not as an individual. In 1996, it was caught on the Wash again and given an individual set of rings. It was never caught again but was seen many, many times – most recently on 12 April 2001 by the late John Parslow.

Getting old

oldestThe annual renewal of a wader’s feathers enables an unringed individual wader to hide its age. The picture alongside was taken by Allison Kew, of the Wash Wader Ringing Group. This ringed Oystercatcher was well into its thirties at the time – older than any of the people in the photograph.

If still alive then a bird will migrate and attempt to breed in the same way as in the previous year, repeating the process for decades. Senescence probably kicks in eventually; there is some evidence of lower annual survival and reduced breeding success at the upper end of a species’ life-span. Long-term colour-ringing will enable this topic to be explored further in due course.

Survival

As mentioned earlier, although the longevity of a species might tell us something about annual survival rates, in that birds with high longevity almost certainly have the highest survival rates, being able to measure the proportion of adult birds that survive from one year through to the next is far more valuable.

Blog adultWaders adopt a ‘high-survival and low breeding-output’ strategy. Most waders have an annual survival rate of between 70% and 90%. This means that a pair of Lapwings, for instance, only needs to raise an average of 0.7 chicks per year to maintain a stable population. Unfortunately, this is not easy to achieve, as you can read here.

The occasional good breeding season can give a real boost to population levels, as we saw for Icelandic Black-tailed Godwits in the summer of 2017, as you can read here.

By collecting records of colour-ringed birds it is possible to measure the annual survival rates of wader populations, as explained here in this blog about Bar-tailed Godwits.

great knotWhen survival rates drop, the effect on population levels is immediate and dramatic, as discussed in this blog about the waders that use the Yellow Sea. Populations of Bar-tailed Godwit, Red Knot and Great Knot that winter in Australia and New Zealand were particularly badly affected by habitat removal, leading to a sudden drop in survival rates and rapid declines in numbers.

Please help to measure survival rates

The chance of finding a ringed bird that breaks a current longevity record is tiny but every birdwatcher who reports a colour-ringed wader is helping to monitor survival rates. If you have ever done so – thank you.

 


 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

 

 

 

 

 

WaderTales blogs in 2017

19 WaderTales blogs were published in 2017, celebrating waders and wader research. Many of the articles are based on newly published papers, with the aim of making wader science available to a broader audience. Click on a link in bold to read an individual blog. 

Wader/Shorebird science and conservationringed-plover

Black-tailed GodwitsDSCN1827

b-dunlinIceland-based research

Blog adultBreeding Lapwings

Upland CurlewsRC single bird muddy edge

There are nearly 30 other WaderTales blogs. Here’s the full list. The intention is to add one or two new blogs each month. You can sign up to receive an e-mail notification when a new one is published.


GFA in IcelandGraham (@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.

Sheep numbers and Welsh Curlew

Blog Jill PThis new paper from Ian Johnstone and RSPB colleagues, in The BTO journal Bird Study, provides some interesting evidence as to how the distribution of breeding Curlew in Mynydd Hiraethog (North Wales) relates to habitat. Amongst other things, they conclude that the amount of sheep grazing is critical to the future recovery of the species in this area.

Correlates of Distribution and nesting success in a Welsh upland Eurasian Curlew population by Ian Johnstone, Dave Elliot, Chris Mellenchip & Will Peach. Bird Study https://doi.org/10.1080/00063657.2017.1411466

The bigger picture

old blogsInternationally, the Eurasian Curlew is designated as near-threatened because of the rapid declines in numbers across the species’ range. Irish conservationists are worried that the species may soon disappear as a breeding species and Welsh birds may not be many years behind, if the current population trajectory continues. For more background see this WaderTales blog: Is the Curlew really near-threatened?

While conservation measures such as ‘habitat improvement’ and ‘predator control’ are already being used in specific recovery projects it is still important for scientists to use current evidence to tease apart the factors that may be affecting the distribution and breeding success of Curlews. An earlier WaderTales blog, summarising a paper by Sam Franks and colleagues from BTO and RSPB, concludes that habitat changes and predator impacts have combined to cause declines and lists some of the specific factors involved. Across Great Britain, they found that semi-natural grasslands support the highest densities of Curlew and population declines were highest in areas with more crows and foxes. See this WaderTales blog: Curlews can’t wait for a treatment plan.

The Curlews of Mynydd Hiraethog

H site

Looking down from the moorland of Hiraethog into intensively manged farmland in the valley

Mynnydd Hiraethog is a discrete 150 km2 upland block of high grass and heather moorland with adjacent lower, enclosed and largely agriculturally improved farmland. The area is managed for livestock farming and forestry and nearly half of the moorland was designated as a Site of Special Scientific Interest (SSSI) in 1989 because of the importance of its upland habitats for birds. The mountains of North Wales have long been grazed by sheep, with peak densities occurring in the Hiraethog region in about 1999. Agreements with farmers have reduced stocking levels, in order to enable overgrazed habitats to recover.

This study focuses upon the relationship between habitat variables and Curlew numbers in a landscape containing agriculturally improved farmland and moorland that was partly protected and subject to grazing reductions for nature conservation. Thirty, random 1 km squares, stratified by historical population trend, were surveyed for Curlew density and nesting-success. Habitat-related and predation-related variables such as ground cover, plant communities and crow numbers were collected to test for associations between Curlew distributions and environmental variables.

Blog BelseyCurlew numbers in the study area declined by 29% between 1994 and 2008, which is much lower than the decline of 46% across the whole of Wales in the same period (Breeding Bird Survey). By studying a mix of squares in which Curlew numbers had increased, remained stable and declined, the researchers were able to maximise the power of the tests. As expected from previous studies, densities in the moorland edge were higher than in improved farmland (there’s plenty of detail in the paper). There were fewer Curlews in areas with higher vegetation density, with 78% of pairs in survey squares with below-average ground cover. In dense cover, prey may be harder to detect and access.

By focusing on key plant species that are associated with particular habitat types, the team were able to identify links with Curlew abundance and nesting success. As predicted, they found that breeding abundance was positively related to the presence of mat-grass Nardus stricta, which grows as tussocks and is associated with rough grazing. Nesting success was higher in areas with more cover of deer-grass Trichophorum germanicum, a sedge that is found in bogs and on wet moorland. Blanket mires are known to support populations of surface invertebrates, which are particularly important to chicks.

GT predatedWoodland may provide look-out perches and nesting habitat for avian predators and den-sites for foxes and other studies have shown that waders are less numerous close to woodland, either because of a direct predation effects or because waders avoid areas of perceived danger (as discussed in this WaderTales Blog – Mastering Lapwing Conservation). There was only weak evidence of reduced Curlew abundance in areas with more woodland in the Hiraethog area. Fox and crow control takes place across the whole area (for livestock protection) so there was insufficient variation to look at any effects that predator numbers may have on distribution or breeding success.

What next for Curlews?

On Hiraethog, much of the rough grazing, characterised by Nardus stricta, and mire, characterised by Tricophorum germanicum, is contained within the SSSI, and the RSPB authors affirm that these habitats should continue to receive protection from developments such as agricultural intensification and tree planting.

Curlews preferentially occupy locations within the moorland/farmland edge. Historically there has been concern over impacts on upland breeding waders of high sheep grazing pressure but more recently worries have been expressed over under-grazing of some upland habitats in Wales. In Hiraethog, the fact that fewer breeding Curlews were found in areas of dense vegetation is consistent with under-grazing having potentially contributed to a decline in habitat suitability.

somewhere else

Welsh moorland, with blanket bog in the foreground and a mosaic of grassland in the background

There was a 46% drop in sheep numbers in Hiraethog between 1995 and 2009, according to figures from Natural Resources Wales, in order that priority habitats would recover from historical overgrazing. This reduction in grazing pressure has probably resulted in increased vegetation density and reduced sward suitability for Curlew. Vegetation density was higher inside the SSSI than in comparable habitats outside, particularly for habitats preferred by Curlew such as heath and rough grazing.

The authors recommend that management of the SSSI for Curlew should include increases in livestock grazing of appropriate type and intensity.  These should be targeted at rough grazing and mire, in areas that have a history of Curlew occupation and that have high current vegetation density. It is hoped that modest and localised increases in grazing pressure can reduce vegetation density without negatively impacting on protected habitats. If successful, and implemented in an experimental manner, then similar treatments may well be trialled elsewhere.

The full paper can be accessed here

Correlates of Distribution and nesting success in a Welsh upland Eurasian Curlew population by Ian Johnstone, Dave Elliot, Chris Mellenchip & Will Peach. Bird Study https://doi.org/10.1080/00063657.2017.1411466


 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

 

 

 

Farming for waders in Iceland

Across the world, agriculture is one of the primary threats to biodiversity, as we tear up natural environments to create more space to feed an ever-growing and increasingly meat-hungry human population. Agricultural land can, however, also provide key resources for many species whose behaviours align with the rhythms of the farming year.

blog cows

In Iceland, farming areas support large and important populations of several wader species, including 75% of Europe’s Whimbrel and over half of Europe’s Dunlin. As the country welcomes more tourists and expands the range of crops grown for food and fuel, what might be the implications for iconic species such as Whimbrel, Dunlin and Black-tailed Godwit?

This paper by Lilja Jóhannesdóttir, of the University of Iceland, and colleagues there and at the universities of Aveiro (Portugal) and East Anglia (UK), investigates the use of farmland by waders living in a semi-natural landscape.

Paper details: Use of agricultural land by breeding waders in low intensity farming landscapes Lilja Jóhannesdóttir, José A. Alves, Jennifer A. Gill, & Tómas Grétar Gunnarsson Animal Conservation. doi:10.1111/acv.12390

A dynamic landscape

blog snipe postIn Iceland, volcanic activity poses serious short-term threats to agriculture, especially in areas close to the mid-Atlantic ridge, which runs through the island from south-west to north-east. Threats from volcanoes include ash-fall, lava, flooding of glacial rivers and earthquakes but, on the plus side, nutritional inputs from volcanoes have beneficial effects on soil fertility in these central areas. Over time, and with the assistance of wind and water, many of these nutrients collect in the lowlands of the country – the areas that now form the main agricultural areas, especially in the warmer south.

The distribution of breeding waders varies across lowland Iceland. A survey carried out between 2001 and 2003 showed that wader densities were greater in areas of the country that had been subject to higher rates of volcanic ash deposition with, for instance, three times as many waders in the south as in the west. See How volcanic eruptions help waders. As was shown in the paper at the heart of that blog, the nutrient signal associated with ash-fall breaks down in farmland. Here, perhaps as a consequence of the application of natural and artificial fertilisers over decades or even centuries, there is no association between ash-fall and wader density. Across the whole country, irrespective of the proximity of volcanoes, nutrient-rich agricultural land attracts waders – but which wader species and across which farmland habitats?

Waders and agriculture

In a previous paper, Lilja Jóhannesdóttir showed that over 90% of Icelandic farmers think it is important or very important to have rich birdlife on their estates, but that farmers also expect to increase the area of farmed land in the coming years. There’s more about this in the WaderTales blog: Do Iceland’s farmers care about wader conservation? It is important to understand the ways that waders currently use farmland, in the hope that nesting waders can continue to be accommodated within the future farming landscape of Iceland.

blog oyc bare

Perhaps Oystercatchers think that the fields have been ploughed especially for them?

Agriculture in Iceland is still relatively low in intensity and extent, and internationally important populations of several breeding bird species are abundant in farmed regions. Only about 2% of land is cultivated (about 7% of lowland areas), of which about 85% is hayfields (grass fields managed to produce crops of grass for storage as winter feed) and 15% consists of arable fields (mostly barley). This is similar to areas such as Norway, northern Canada and northern and western areas of the British Isles but contrasts sharply with the US and many countries in the EU which, on average, have 20% or more of their land under cultivation.

In these high-latitude landscapes, agricultural land can potentially provide resources that help to support wader species. To address these issues, Lilja conducted surveys of bird abundance on 64 farms in northern, western and southern areas of Iceland that vary in underlying soil productivity, and quantified:

  • Levels of breeding bird use of farmed land managed at three differing intensities, ranging from cultivated fields to semi-natural land
  • Changes in patterns of bird use of farmed land throughout the breeding season.

Farm survey

In Iceland, there are still large patches of natural or semi-natural habitats; they surround the hay-fields and arable fields that are at the heart of many farms. This arrangement creates gradients of agricultural intensity from the farm into the surrounding natural land, tapering from intensive management to moderate and light management.

BLOG gradient

The three intensity levels within Icelandic farmland can be roughly described as follows:

  • Intensive: Hayfields (85%) and arable fields (15%) fields. Most hayfields are mown twice per year and ploughed and reseeded every few years.
  • Moderate: Old hayfields that are rarely or never mown but are used for grazing, or fertilized grasslands used for livestock grazing.
  • Light: Semi-natural or natural areas under low intensity grazing, usually by sheep or horses, or with no agricultural influence, ranging from sparsely vegetated habitats to habitats with abundant vegetation (where grasses and bushes dominate the vegetation) and with a broad wetness gradient.

Fields corresponding to these three categories were surveyed on the 64 farms, firstly during the egg-laying and incubation period and then later, to coincided with chick rearing.

blog 3 habitats

Gradient of management from intensive (left) to wet semi-natural (right)

Where were the waders?

blog RK on postLarge numbers of waders were encountered in all transects in all parts of Iceland, with Black-tailed Godwit and Redshank contributing most records. There were also important numbers of Oystercatcher, Golden Plover, Dunlin, Snipe and Whimbrel. Overall, wader densities on farms did not vary significantly between regions or between early and late visits but there were some subtle differences:

  • Wader density varied significantly along the management gradient, with lower densities tending to occur in more intensively managed areas, particularly in the early (nest-laying and incubation) season.
  • Intensively managed fields in the west (where underlying soil productivity is lower) had higher densities of waders than in the north and south of the country.
  • There were seasonal declines in wader density on all three management types in the south, but seasonal increases on intensive and moderate management in the west and in fields under moderate management in the north.
  • There were some differences between species in these patterns (more details in paper).

blog redshank westOne of the interesting differences in the west was the redistribution of Redshank as the season progressed. There were three times as many pairs of Redshank in cultivated land during the chick-rearing period than during incubation, suggesting that adults may be moving broods into cultivated land. Resources for chicks may well be relatively more abundant or accessible in these areas, given the relatively low levels of nutrients in areas that are a long way from the active volcano belt. There’s also a suggestion that drainage ditches around cultivated fields in the west may provide important resources for Snipe.

What about the future?

blog distributions

Wader densities during the early (red) and later (blue) part of the breeding season (Modified from the paper in Journal of Animal Conservation)

Although the density of birds in Iceland’s agricultural landscapes tends to be higher in lightly managed than intensively managed agricultural land, densities in the areas under the most intense agricultural management are still high, suggesting that agricultural habitats provide important resources within these landscapes (see figure alongside). These density estimates (between 100 and 200 waders/km2) are typically much higher than those recorded in other countries in which these species breed.

Farmers in Iceland expect to expand their cultivated land in the coming years in response to increasing demand for agricultural production (Do Iceland’s farmers care about wader conservation?), and evidence from other countries throughout the world has shown how rapidly biodiversity can be lost in response to agricultural expansion and intensification. Protecting these landscapes from further development is crucial to the species that they support.

The authors suggest ways in which farming practises might change wader distributions in Iceland. Here are a few of the interesting points that they make:

  • When wader-rich semi-natural land is replaced by arable farming and intensively-managed hayfields, this is likely to reduce overall wader densities.
  • Losing wet features, which provide insect food for waders, may well have impacts for chick growth. Here’s a WaderTales blog that discusses the importance of wet features to Lapwings in the UK.
  • In other countries, early grass mowing is a direct threat to nests and chicks. Clutch and brood losses are already being observed in Iceland and, with warmer springs encouraging earlier grass growth, this could become more of a problem.
  • The conversion of less-intensively managed areas into farmland is likely to have most effect on Dunlin, Black-tailed Godwit and Whimbrel, which tend to occur in their highest densities in the least intensively managed lowland areas.

blog walk WhimbrelIt is estimated that between 4 and 5 million waders leave Iceland each autumn, for Europe, Africa and the South Pacific (Red-necked Phalarope). Iceland’s farmland supports many of these birds and this study highlights the need to protect them from the agricultural developments that have led to widespread wader losses throughout most of the world.

You can read the paper here

Use of agricultural land by breeding waders in low-intensity farming landscapes Lilja Jóhannesdóttir, José A. Alves, Jennifer A. Gill, & Tómas Grétar Gunnarsson. Animal Conservation. doi:10.1111/acv.12390

blog oycs & chick

 


 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

 

 

International Shorebird Rescue

Huge numbers of birdwatchers and conservationists across the globe are involved in shorebird/wader conservation.  It all starts with noticing that numbers are changing, then you need to work out why species are in decline, before suggesting ways to treat the problem and monitoring what happens afterwards. The whole process can be regarded as ‘International Shorebird Rescue’ and anyone who takes part in systematic counts of waders is part of the team.

This blog is based upon the plenary presentation that launched the global BOU Twitter conference on 28 and 29 November 2017. You can see the rest of the presentations here, storified on the BOU website. In this talk, entitled International Shorebird Rescue, I tried to highlight the role of shorebird scientists and volunteers in the conservation process.

A Twitter talk is a series of tweets delivered within an allocated time-slot, each of which is usually accompanied by a slide providing more detail. In this blog, I have allowed myself a few more than 140 (or even 280) characters, to try to make the links a little smoother. The first slide, showing all of the speakers, was produced by Steve Dudley, the BOU’s Chief Operations Officer.

Picture1

I introduced myself and WaderTales to the BOU audience, explaining that I have been studying waders for 40+ years and that my current focus is science communications, particularly via WaderTales blogs, a full list of which is available at https://wadertales.wordpress.com/about/

Picture2

“International Shorebird Rescue” celebrates the role of wader researchers and birdwatchers in conservation. I describe shorebird rescue as a four-stage process – notice there is a problem, diagnose what it is, start a treatment plan and monitor what happens.

Picture3

Shorebird conservation is fuelled by the passion of researchers and policy-makers. I could have chosen many other excellent people to exemplify the way that ‘waderologists’ engage in conservation.

Picture4

Shorebird conservation is not easy because many populations rely on a complex suite of sites during the course of a year. Migratory species such as this Marbled Godwit in North America face different conservation challenges in different seasons. There’s  more about the threats faced by the numeniini in this WaderTales blog. Why are we losing our large waders?

Picture5

Migratory movements of waders were not always well understood. Here’s an example from the 1970s, when shellfishery interests in Wales conflicted with conservation interests in Norway. 

Picture6

How science can inform policy

Thankfully, wader conservation is now more joined-up. In the next few slides I show how counts & scientific papers turn into conservation policy, using the Black-tailed Godwit as an example.

Picture7

Black-tailed Godwits have been experiencing contrasting fortunes with declining numbers of the limosa subspecies and increases in islandica. These two WaderTales blogs provide background:

Dutch Black-tailed Godwit numbers down by nearly 75%

Black-tailed Godwits expand their range in Russia and Iceland

Picture8

By contrasting the different fortunes of the two subspecies, Black-tailed Godwit Species Action Plans were developed at an International Wader Study Group workshop and then published as a Wader Study paper, and by EU and AEWA. There are links to all three here: Wader Study paper, EU Management Plan and AEWA Action Plan. 

Picture9

One of the common problems for declining wader populations at present is poor breeding success. For many species, productivity is too low for sustainable populations to persist, as discussed in this paper about demography.

Picture10

Fencing – an effective treatment plan?

One of the emerging conclusions of recent research in the UK is that we need open discussion about reducing predator impacts on nesting shorebirds. One of the suggested approaches is to deploy electric fences, as in this paper by Lucy Mason (née Lucy Malpas). Lucy presented some of her more recent work later in session one of the BOU Twitter conference.

Picture11

In which circumstances are fences effective and value-for-money?

How are fences deployed in  lowland wet grassland?

Fences are being used to try to reduce predation pressures on Curlew

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The key role of estuaries

Estuaries are of vital importance to a whole range of wader species outside the breeding season. Here they face a multitude of threats, largely because ‘empty’ mudflats can be seen as being ripe for development. In the next few slides I have picked a selection of case studies in which an issue has been identified, data have been collected and conservation action has been proposed/implemented.

Picture13

Waders have been losing mudflats for centuries, as exemplified on the Wash estuary, that sits between Lincolnshire and Norfolk in the east of England. The Wash was at its smallest in the 1970s. Recognition of the importance of the site has acted as a deterrent to planners, who might have claimed even more land for farming or created a large fresh-water reservoir.

Picture14

A more recent physical threat is tidal power, as in the Severn Estuary, between England and Wales. Impact assessments have funded vital research in the area, as discussed in this blog.

Picture15

The booming economy of Asia has put huge pressure on the Yellow Sea. Habitat removal is affecting annual survival rates and severely reducing populations of wader species that are most dependent upon the area. Fortunately, it is not too late to make a difference, as you can read here: Wader declines in the Yellow Sea

Picture16

Conflict with fisheries is usually indirect but the reliance of shorebirds on the eggs of horseshoe crabs is turning the spotlight on fishing regulations in Delaware Bay. Effects of Horseshoe Crab Harvest in Delaware Bay on Red Knots; Are Harvest Restrictions Working?

Picture17

Climate change threatens waders in the breeding grounds and on estuaries. Rising sea-levels and hard sea-walls are squeezing intertidal feeding areas.

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Spoon-billed Sandpipers – true teamwork

As the presentation drew to a close, I wanted to finish with a positive story. Critically endangered Spoon-billed Sandpipers have a desperate need for International Shorebird Rescue and a huge amount of multinational effort is going into their conservation.

Picture19

Head-starting Spoon-billed Sandpipers has been really successful, producing huge gains in productivity. This may be an important conservation tool for other threatened species, as exemplified in this WaderTales blog about Black-tailed Godwits in the washes of Eastern England.

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Away from the Arctic, Spoon-billed Sandpipers face many challenges. The same bird may be impacted by habitat loss in the Yellow Sea during the autumn and by hunting pressure in Myanmar later in the winter.

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Shorebird scientists are working with colleagues and policy-makers in China, S Korea and N Korea to save space for Spoon-billed Sandpipers in the Yellow Sea.

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Quick mention of climate change

Much of current shorebird research is set in a context of climate change. Here’s a link to a blog about the change in timing of migration of Icelandic Black-tailed Godwits.

Picture23

Notice > Diagnose > Treat

In the wader world , the time between ‘paper’ and ‘policy’ can be pleasingly short – because scientists and policy makers keep communication channels open, as has been demonstrated in the case of Yellow Sea.

Picture24 

‘International Shorebird Rescue’ works because passionate birdwatchers, scientists & policymakers work together. They operate within a system of international agreements that have been designed to protect migratory systems and the estuaries and wetlands upon which they rely.

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This blog is based upon the plenary presentation that launched the global BOU Twitter conference on 28 and 29 November 2017. You can see the rest of the presentations by checking out #BOU17TC on Twitter or by visiting the BOU website.

joinThis was a global Twitter conference, organised by the BOU (British Ornithologists’ Union – publishers of IBIS). It involved 70 scientists and science communicators from around the world, tweeting in their own time-zones for 26 hours. The BOU plays a pivotal role in ornithological communication and this was a great example of global cooperation – it does seem appropriate that ornithologists have taken to Twitter so readily!


 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

 

25 years of wader declines

This article summarises a Bird Study paper arising from a 25-year Scottish study of breeding Lapwing, Oystercatcher, Redshank & Curlew. The story is set against a backdrop of a changing farming landscape.

RC LapThe interesting and sobering feature of this paper about breeding waders by Mike Bell and John Calladine is that its focus is a ‘normal’ area of farmland in Scotland. If you’ve taken the A9 north of Stirling, through Strathallan, then you’ll have driven past the fields. Perhaps you might even have noticed displaying Lapwing, Oystercatcher, Curlew and Redshank? Over a 25-year period, the number of breeding waders in this valley and another one that runs northwest and that can be seen from the B827 has dropped from 600 pairs to just 76 – that’s a loss of 87%, or over 20 pairs per year.

So, what has changed in this part of Scotland that might be linked to these declines? The authors conclude that the reduction in numbers can be linked to changes in field management. Put simply, there are too few bare fields in the spring for Oystercatcher (down 95%) and Lapwing (down 88%). These two species hide their nests in ‘plain site’; they watch out for predators, take off early and hope that the eggs are coloured cryptically enough to avoid detection. Having left their nests, they attempt to deter and/or distract prowling crows etc.  Redshanks (down 87%) and Curlew (down 67%) have also declined, even though they hide their nests in long grass, about which more later.

map graph

Lapwing declines in the Strathallan area are not that much different to those that have been charted across much of Britain & Ireland

In for the long haul

In a survey in the late 1980s, this area of Strathallan held an important assemblage of farmland breeding waders, with particularly high densities of nesting Lapwing. Land use in the valley is predominantly agricultural, with a mixture of arable fields and grazing by sheep and beef cattle. It is a relatively open landscape with few hedgerows, some scattered shelter belts and small conifer plantations.

KS RedshankThis study started in 1990, when breeding densities of nesting Oystercatcher, Lapwing, Redshank and Curlew in the core area were still high, at 11.7, 35.6, 4.7 and 3.3 pairs/km2 respectively. Unlike a PhD project, which might include three years of data, Mike Bell has kept this survey going for 25 years. Mike is the volunteer Regional Representative for the British Trust for Ornithology’s Perthshire region.

Breeding waders within a core area of 65 fields and a small amount of wet fen were surveyed annually from 1990 to 2015. The field sizes were small, by modern standards, with only five fields larger than 20 ha. An additional 1 km2 of lowland mixed farmland was surveyed in most years, 4 km2 of moorland rough grazing was surveyed in four years and another 5.3 km2 of enclosed and unenclosed rough grazing and moorland was surveyed at the beginning and end of the survey period only.

Land management and usage were recorded for each field on the first visit in April or early May. Spring sward height in each field was recorded as one of three categories: no vegetation, short (<10 cm) or long (>10 cm). These sward categories comprised the following field types:

  • bare – ploughed or tilled land with no emergent vegetation
  • short – managed grass for grazing or mowing for hay or silage, rough grass, rush pasture, spring arable, setaside/fallow.
  • long – managed grass, rough grass, rush/pasture, setaside/fallow, heath/moorland, marsh/wetland, unmanaged rank grassland and woodland/scrub.

Where to find waders in Strathallan

In the early 1990s, Strathallan supported around 36 Lapwing pairs/km2 across the core study area, which is comparable with some of the highest densities reported anywhere in the UK. During the 25-year study, as the numbers of Lapwing, Oystercatcher, Redshank and Curlew declined, an increased proportion of the remaining breeding waders became restricted to areas with fields classed as ‘bare’ in spring, while the greatest losses were in fields with ‘short’ and ‘tall’ spring sward heights (see figure).

graphic

Changes in breeding densities of waders in Strathallan, on fields with different sward heights

Breeding densities of Curlew were low throughout the study area and, although overall numbers declined, there was low power to detect statistically significant changes. There were different patterns of change for Lapwing, Oystercatcher and Redshank within fields of different spring sward heights:

  • The least marked changes were in fields with no vegetation in spring.
  • Fields with short swards showed the largest declines.
  • The tallest spring sward heights supported the lowest densities of the three wader species, with Redshank present generally at low densities in all vegetation categories.
UK BBS

UK-wide Breeding Bird Survey trends for Oystercatcher, Redshank and Curlew. BBS is organised by BTO in partnership with JNCC and RSPB.

A changing farmland landscape

Sward heights reflected changing farming methods. Looking at the fields in terms of cropping regimes.

  • The highest densities of Oystercatcher were in spring-sown arable crops.
  • Rush pasture was the most favoured field type for Lapwing and Redshank at the start of the study but the amount of this habitat declined during the study, as farmers created semi-permanent pastures for over-wintering sheep. When this happened, birds became more restricted in their nesting distribution.
  • By 2015, very few fields were still under a crop rotation of grass and spring arable, that would have delivered a mosaic of sward structures. By this time, half of the Lapwing pairs were nesting in just four fields.

Breeding success

The breeding success of Lapwings was estimated in five sample fields that could easily be observed from roads or tracks without disturbing the adults. Lapwing productivity was less than 0.60 young fledged/pair (the bench-mark for a typical stable population) in all but three years and it was less than 0.25 young fledged/pair in 14 of the 22 years. With very low recruitment rates, it is not surprising that the Lapwing is in decline.

There are several WaderTales blogs about Lapwings breeding in lowland wet grassland, including A helping hand for Lapwings. A full list of WaderTales blogs can be found here.

What is changing?

TGG Oyc

The changing fortunes of Oystercatcher are discussed in this WaderTales blog

Within a mixed arable-pasture farmland environment, bare field and short swards in spring appear to be important to breeding waders. Losses of these preferred habitats type don’t appear to fully account for the decline in numbers, however.

Alongside changes to farmland habitats, other potential factors that could have contributed to the decline of the wader population in Strathallan include an increased incidence of poor spring weather, increased disturbance (including from dog-walkers in some fields in some years) and an increase in predators. Mike Bell thinks that one of the reasons for a possible link between productivity declines and wet weather is that birds are nesting in sub-optimal (long) grass and hence more affected by wetter conditions. He writes about this and potential reasons for increased disturbance in an upcoming article in Scottish Birds. A link to the Scottish Birds article will be included when available.

Densities of avian predators increased in Strathallan during the study period, with higher breeding densities of Carrion Crow and Buzzard and an increasing frequency of bigger flocks of non-breeding crows. There was no detectable change in breeding success during the study but it is possible that nest success was already depressed by predation when the study commenced.

A relentless decline

GHH pictureAlthough previously identified as a good area for breeding waders, in a Scottish context, there is nothing unique about this Strathallan study area. It is good to see these issues explored in Bird Study, the BTO journal. I am sure that the editor, Ian Hartley, will have been pleased to publish a paper based on a nice mix of dedicated fieldwork and scientific analysis – that’s what the BTO is all about.  If you want to understand the (not yet fully explained) sad demise of breeding waders in Scotland, check out the figures in the paper. These show a relentless, 25-year decline in nesting densities across a range of habitats and some less-than-subtle changes in the way that fields are now managed.

Here’s a link to the paper:

The decline of a population of farmland breeding waders: a twenty-five-year case study by Michael V. Bell & John Calladine in Bird Study, 64:2, 264-273 DOI: 10.1080/00063657.2017.1319903


 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

 

 

Wetland Bird Survey: working for waders

Red-listed Curlews, Scottish Oystercatchers, a boom in Black-tailed Godwits and the need for safe roost sites. Here’s a selection of WaderTales blogs that may appeal to counters who contribute to the UK Wetland Bird Survey (WeBS) and other birdwatchers who like waders/shorebirds.

Blog RINGOS

It’s 70 years since UK birdwatchers started to count waders and waterfowl and there are now over 3000 registered Wetland Bird Survey volunteers.

WeBS70logo6a_smallThe work that volunteers do to chart the rises and falls of species as diverse as Redshanks and Whooper Swans provides a unique insight into the fortunes of our wintering waterbirds. As a tribute to the people behind the binoculars and telescopes, I highlight seven WaderTales articles that use WeBS data. Click on the links in bold if you want to read a particular story.

Curlew counts

curlew

WeBS counts for Curlew in Great Britain between 1974 and 2016

In the blog Is the Curlew really near-threatened? WeBS counts are used to show how numbers have changed over the decades. There might have been a boost in numbers when Curlew came off the hunting quarry list in Great Britain in 1981 but declines in the last 15 years reflect issues birds face in the breeding season in many parts of their European range.

Internationally, Eurasian Curlews are classified as near-threatened and in the UK they are now red listed. WeBS counts in Northern Ireland, alongside I-WeBS counts in the Republic, were successfully used to argue for the cessation of shooting across the island of Ireland in 2012.

Scottish Oystercatchers

L17A9623 (2)

Oystercatchers are unusual, amongst waders, in that they feed their young

Surely the Oystercatcher is one wader species that we don’t need to worry about? Although the blog Oystercatcher: from shingle beach to roof-top leads with nesting behaviour, WeBS counts are used to illustrate regional trends in different parts of the United Kingdom. In Scotland, there is concern about poor breeding success, while in parts of Wales and England, WeBS counts may provide a way of measuring the population-level effects of cockle fishing and diseases affecting shellfish.

oyc webs

Three very different trajectories for national WeBS counts for Oystercatchers since 1974

Mid-winter movements

figureThe annual WeBS report highlights the months in which counts are at their highest in different estuaries. For Knot, for instance, the highest counts on the Wash are in September, in other east-coast estuaries and on the Dee the peak is in December, whilst further north, in Morecambe Bay and the Solway, top numbers occur in January and February.

In Godwits & Godwiteers, which focuses on the superb work of observers who track the movements of colour-ringed Black-tailed Godwits, WeBS counts from east coast estuaries and the Ouse Washes illustrate the move inland that occurs as the winter progresses.

National patterns and local counts

blogGroups of WeBS counters who cover local estuaries will be the first to notice changes in the numbers of the key species that use their own sites. If the number of Dunlin drops, is that a local phenomenon or part of a national picture? Is there always a strong link between national declines (or increases) and site-based counts? Interpreting changing wader counts provides some answers. It emphasises just how reluctant waders are to change wintering sites between years.

High-tide roosts

horse-and-flockEvery WeBS counter will appreciate the value of a safe (undisturbed) roosting site, whether this be used by waders or by ducks and geese. In A place to roost, WeBS counts for Black-tailed Godwits are used to assess the national and international importance of an individual roosting site in northwest England. The main thread, however, is about the energy expenditure associated with sleeping (not very much) and travelling to and from a safe roost site (lots). An interesting add-on is the story of what happened to Cardiff’s Redshanks when the estuary was turned into a lake.

New recruits

If adult birds don’t change their winter homes then increases in local populations may well reflect good breeding years for wader species. 2017 seems to have been one of the good years for several species that breed in Iceland, particularly Black-tailed Godwits. WeBS counters should not be surprised if there are really high counts this winter.

T with BTGA great summer for Iceland’s waders puts this year’s productivity into context and gives an update on wader research that is being undertaken by the South Iceland Research Centre (University of Iceland), the University of East Anglia (UK) and the University of Aveiro (Portugal). If you have ever seen a colour-ringed Black-tailed Godwit, Ringed Plover, Oystercatcher or Whimbrel you may well find this interesting.

On the open shore

NEWS tableThe blog News & Oystercatchers was written to promote the Non-estuarine Waterbird Survey of 2015/16, or NEWS-III. There are a lot of waders on the shorelines that link the estuaries that are covered for WeBS and, every few years, volunteers are asked to count these birds. In NEWS-II (2006/07), it was estimated that 87% of Purple Sandpipers were to be found on the open shore (see table) with high numbers of several other species. There’s an initial assessment of the results for NEWS-III in the latest WeBS report and I look forward to writing up the results as a WaderTales blog, once a paper is published.

Links to blogs mentioned already

Many more to choose from

There are over 40 WaderTales blogs to choose from in this list. Four of these articles might be of particular interest to WeBS counters:

  • knot

    Knot migration

    Which wader, when and why? gives an overview of the migration of waders into, out of and through Britain & Ireland. The patterns help to explain why the peak numbers for Sanderling occur on the Wash in August, on the Dee in November and on the North Norfolk coast in May, for instance.

  • Bar-tailed Godwits: migration & survival  contrasts the different migration patterns of the two races of Bar-tailed Godwits that use British & Irish estuaries and explains the importance of colour-rings in the calculation of survival rates. On the other side of the world, Wader declines in the shrinking Yellow Sea shows how quickly numbers can change if the annual survival probabilities of adults fall. sum plum
  • The not-so-Grey Plover focuses on the Grey or Black-bellied Plover but the real story is about moult. British and Irish estuaries are important to huge numbers of moulting waders. WeBS counters often don’t have time to look at individual birds but, with the right camera, you can learn a lot about waders by checking out the right feathers.

Thank you

Blog Counter 1I use WeBS data a lot – in my blogs and in articles – and I appreciate the tremendous value of data collected each month by thousands of contributors. They monitor the condition of their local patches and have directly contributed to local, national and international reviews of the conservation status of wintering waterbirds. To every current and past WeBS counter – ‘thank you!’

There’s a (large) selection of papers using WeBS data here, on the BTO website. The Wetland Bird Survey is run by the BTO, in partnership with RSPB and JNCC (which acts on behalf of NE, NRW, SNH & DAERA), and in association with WWT.


 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

Interpreting changing wader counts

Blog mixed flockWhen you count the number of Redshank on your local estuary and discover that there are fewer now than there were last year –  or five, or twenty years ago – what are the implications? Is this part of a national or international trend or has something changed within the estuary itself?

The first question to ask is, ‘what is happening elsewhere?’ and then to wonder about the ways in which numbers of birds in different sites might relate to each other. What actually happens to local counts when national counts go down – or go up, for that matter?

The UK Wetland Bird Survey (WeBS) data provide comprehensive and long-term monitoring of estuarine wader populations around our coastline. Thanks to volunteers who collect monthly counts each year, these data present an excellent opportunity to explore how bird distributions can change over time. A new paper by Verónica Méndez and colleagues from the University of East Anglia and British Trust for Ornithology uses counts of 19 species (18 waders plus Shelduck, an honorary wader) over a 26-year period to ask what happens to distribution and local abundance across our estuaries when overall population sizes go up or down.

Consequences of population change for local abundance and site occupancy of wintering waterbirds Verónica Méndez, Jennifer A. Gill, José A. Alves, Niall H. K. Burton & Richard G. Davies Diversity and Distributions. 2017;1–12. DOI: 10.1111/ddi.12653

The counters

Blog Counter 2A WeBS count can be a tough assignment for a volunteer birdwatcher. Being allocated to a stretch of an estuarine coastline and asked to visit it, whatever the weather, on a given weekend of every month, in every winter, is not the same as an invitation to go birdwatching in September to look for a Curlew Sandpiper.

The counts used in this paper are from the months of November through to February, when waders are largely settled for the winter and the weather can be less than clement. Many of the data-points for individual sites have been collected by the same person in all of the years analysed in the paper and every contribution is important.

WeBS70logo6a_smallWeBS is the successor of other, similar count schemes which are celebrating 70 years of continuous monitoring this year. It is organised by BTO, in partnership with RSPB and JNCC and in association with WWT. There are over 3000 registered WeBS volunteers, collecting data about the waterbirds that can be found on estuaries, in wetlands, on inland lakes, along river valleys and in local parks and villages.

Understanding change

Many populations of migratory birds are changing in number quite rapidly at present, but are these changes more likely to result in changes in occupancy (eg colonisation of or extinction from some sites) or changes in abundance within sites? Put simply, if extra waders arrive in the autumn, how do they distribute themselves across available sites? If fewer arrive, where will the gaps be found?

DN and BTG graphs

The contrasting fortunes of Dunlin and Black-tailed Godwit over the period covered in the new paper

Over the period studied in the paper (between 1980-85 and 2002-07), populations of five species declined, with the greatest losses occurring in Purple Sandpiper and Shelduck (both declined by about 25%), while there were increases for four, the biggest of which were Avocet (+1690%), Golden Plover (+554%) and Black-tailed Godwit (+418%). No birdwatcher will be shocked by the figures for Avocet or Black-tailed Godwit, wintering numbers of which have shot up, but Golden Plover is more of a surprise and may be linked to a move from inland fields to estuaries.

When the size of a wintering population of waders declined, Verónica Méndez and her colleagues found that the main consequence was a reduction in numbers across all sites. Birds were likely to stay on a site even if local numbers were dwindling. This suggests high levels of site-fidelity by individual waders, which is something we know from ringing and tracking studies. If you’re still alive then just do the same again – there could be a better site with a higher number of conspecifics somewhere else but it would be risky to try to find that out.

 

Blog Avocets

Thirty years ago, few people can have expected that they would ever see such a large flock of Avocets on the Humber

If the size of a wintering population increased, generally numbers went up within all occupied sites. The exceptions tended to occur in species for which original numbers were very small, such as for Greenshank, or species for which the change in numbers has been rapid – as seen in Avocet and Black-tailed Godwit.

If adults don’t change their wintering sites then increases are presumably being driven by juveniles. Their settlement decisions may be influenced by the distribution of adults of the same species, resulting in increased local abundance, rather than colonisation of new sites. For the two rapidly-expanding species, Black-tailed Godwit and Avocet, there was colonisation of 25 and 15 new sites, respectively, between 1980-85 and 2002-07, with some indication of more similar increases in sites that were closer together, which may reflect local movements among groups of nearby sites.

Designating sites

Blog Blackwit

Juvenile waders may well settle in areas where there are already populations of wintering adults

One of the key conservation measures for waders across Europe is the Special Protection Area (SPA) network, a collection of sites that are designated because they hold internationally or nationally important numbers of species, measured as a percentage of the population. Designated sites need to maintain numbers of all the species that hit this threshold percentage. However, if a national or European population gets larger (for example because of high breeding success) but the number on a particular site does not grow (or grows more slowly), then the species might drop below the threshold for protection, even if the site is unchanged. Theoretically this could affect a site’s protected status for that species, although is unlikely to be a problem, as most sites are designated for many species.

This new paper shows that gains and losses tend to be fairly constant across all sites, making it unlikely that a site designation would be affected by national or European-scale changes. In only one species (Ringed Plover), have numbers declined so much in some sites that the total number of sites exceeding the threshold for that species has decreased.

Keep counting!

Blog Counter 1Habitat availability and site fidelity, along with species longevity, may explain the strong tendency for local population abundance to change much more than site occupancy, in our wintering waders. Given the statutory importance of maintaining waterbird populations in designated protected areas, it is important to continue local and national surveys that can identify changes in local abundance and relate these to large-scale processes.

Returning to the earlier question – When you count the number of Redshank on your local estuary and discover that there are fewer now than there were last year –  or five, or twenty years ago – what are the implications?

This new paper shows that it is unlikely that a local drop in a species’ numbers is caused by a redistribution of birds. Factors that might lie behind a local decline need to be investigated locally, if the trend is not replicated elsewhere. The authors could only reach this conclusion because they had 26 years of WeBS data from a range of sites at their disposal. Future generations of WeBS counters will hopefully continue to monitor the conditions of our estuaries, working together throughout the country to interpret local counts within a national framework.

Paper

Consequences of population change for local abundance and site occupancy of wintering waterbirds Verónica Méndez, Jennifer A. Gill, José A. Alves, Niall H. K. Burton & Richard G. Davies Diversity and Distributions. 2017;1–12. DOI: 10.1111/ddi.12653

Blog RINGOS


 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