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, how might warmer conditions have led 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.

blog pete ruth

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.

 

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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).

buffers

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

nesting RNP

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).

graphic

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?

blog poultry

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.
  • blog vole

    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.

  • blog Tern chick

    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

blog 3 terns 1 kestrel


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.

 

 

Tool-kit for wader conservation

andyhayDecades of drainage and agricultural intensification have caused huge declines in numbers of breeding waders in the lowland wet-grasslands of Western Europe. Although we were already well aware of these problems by 1995, and farmland prescriptions have been used to try to arrest the declines since then, we have still lost nearly half of Britain’s breeding Lapwing in the last twenty years. Even on nature reserves and in sympathetically-managed wet-grassland, it has proved hard to boost the number of chicks produced. Why is this and what else is there that can be done?

bouThis is a summary of a presentation by Professor Jennifer Gill of the University of East Anglia and Dr Jen Smart of RSPB, delivered at the BOU’s Grassland Workshop (IOC Vancouver, 2018).

There are five key techniques in the tool-kit used by conservationists trying to support breeding waders:

  • Make the site attractive to waders
  • Manage predator numbers, particularly through lethal control
  • Manage habitat structure to make alternative prey available
  • Exclude predators, either permanently or temporarily
  • Invest in head-starting chicks, to boost productivity

Size of the problem

redshankThe decline in wader numbers in England has been happening for a very long time. In just the period 1995-2016, Lapwing numbers have fallen by a further 26% and Redshank numbers by 39%, according to Bird Trends, produced by BTO & JNCC. Within the English lowlands there has been a dramatic contraction into nature reserves, especially in the east of England.

The Breeding Waders in Wet Meadows survey showed that fields that are within nature reserves are much more likely to be occupied than other fields in wet grassland, particularly those that are included in wader-specific agri-environment schemes. The study is published in Ibis by Jen Smart et al.

smart 2014

Attracting breeding waders

Lowland wet grasslands in Broads

Creating shallow ditches. Mike Page/RSPB

Reserve managers and sympathetic landowners have become very good at creating the sort of habitats that attract breeding Lapwings. Autumn and winter grazing can be manipulated to produce short swards, whilst adding in shallow pools and foot-drains (linear features running through fields) increases feeding opportunities for chicks. See Restoration of wet features for breeding waders on lowland grassland 

The RSPB has invested heavily in time and equipment to deliver these lowland west grasslands, on their own land, on other nature reserves and on commercial farmland. By working with Natural England, they have helped to shape agri-environment schemes that can be used to deliver payments to farmers who are well-placed to create habitat that suits breeding waders.

Mark

wader pairsIn the east of England, there are now more than 3000 hectares of this attractive, well-managed wet grassland habitat, designed to be just right for species such as Lapwing. The graph alongside, drawn using RSPB data, shows the number of pairs of Lapwing (green), Redshank (red) and other waders (Oystercatcher, Avocet & Snipe: blue) in Berney Marshes RSPB reserve in eastern England for the period 1986 to 2016. There were early successes, as new areas were purchased and transformed, but growth in wader populations has not been sustained, despite ongoing improvements in land management. What is preventing further recovery?

Demographic processes

survivalIn a paper in the Journal of Ornithology, Maya Roodbergen et al  used demographic data collated across Europe to show that there had been long-term declines in nest survival and increases in nest predation rates in lowland wader species. One of the main focuses of management action at Berney Marshes is to maximise Lapwing productivity but nesting success is still below 0.6 chicks per pair in most years (see graph), which is the minimum estimated productivity for population stability (Macdonald & Bolton). Not enough chicks are being hatched, with the vast majority of egg losses being associated with fox activity.

Controlling foxes

The obvious solution for breeding waders must surely be to shoot foxes? It’s not that simple. In a multi-year, replicated experiment to assess the impact of controlling foxes and crows, RSPB scientists showed that there were no clear improvements in wader nesting success; effectiveness is very much site-specific. Much may well depend on how much fox control there is in the surrounding area.

foxIf fox impacts cannot be reduced sufficiently through lethal control, perhaps it is possible to reduce their effects on waders by understanding the ways in which foxes forage and to adapt the habitat appropriately? Work by Becky Laidlaw and others has shown that Lapwing nest predation rates are lower close to tall vegetation and in areas with complex wet features. However, Becky has also shown that management to create these features, even in areas of high wader density and effective predator mobbing, is only likely to achieve small reductions in nest predation. There is a WaderTales blog about this: Can habitat management rescue Lapwing populations?

Excluding foxes

malpasOne solution to the fox problem that does work is to exclude foxes (and badgers) from an area, by using electric fences. See paper by Lucy Malpas (now Lucy Mason). Fences may be deployed at different scales; just around individual nests, temporarily (around individual fields) or permanently (around larger areas).

  1. Nest-scale may be most appropriate for species such as Curlew, which have large territories and do not nest colonially. Finding nests is time consuming but relatively small lengths of fence could potentially be erected during the incubation period.
  2. Whole-site protection will suit semi-colonial species such as Lapwing. Although expensive to install, permanent fences can require relatively little maintenance and can potentially be powered by mains electricity. One disadvantage may be that the presence of large numbers of chicks can attract avian predators, such as birds of prey, which are themselves conservation priorities and hence difficult to manage.
  3. fence 2Field-scale fences usually rely on batteries, which need to be checked and changed, and fences need maintenance, as the grass grows and can short out the bottom strands. However, deployment at the field-level allows for dynamic use within a farming landscape and in accordance with agri-environment schemes. New research by RSPB and the University of East Anglia aims to see if fences need only to be deployed for relatively short periods. If pairs nest synchronously then groups of birds may be able to maintain the ‘fence-effect’ by mobbing predators, when a temporary fence is removed.

Head-starting

morgan 2018Although it might be possible to improve the habitat that is available for breeding waders and to reduce predation pressure, it is sometimes too late to boost numbers – simply because populations have shrunk to too low a level. At this point, head-starting (rearing chicks from eggs) may be appropriate. This blog celebrates the success of the first year of a joint initiative by RSPB and WWT (Project Godwit) to increase the local population of Black-tailed Godwits in the East Anglian fens: Head-starting Success.

In conclusion

In trying to boost breeding wader populations, land-managers and conservationists have developed techniques to increase site attractiveness and reduce predator impacts, through management, control and exclusion. The tools that are used will depend upon species, budget and conservation priorities.

This work was presented by Jennifer Gill & Jen Smart at a BOU symposium on the Conservation of Grassland Birds, in Vancouver, August 2018.

Blog adultWaderTales blogs about Lapwings and Redshanks

The work of RSPB and University of East Anglia scientists features strongly in these blogs, which focus on support for breeding wader populations in lowland wet grassland and on coastal saltings.


GFA in Iceland

WaderTales blogs are written by Graham Appleton (@grahamfappleton), who  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.

 

 

Head-starting success

The first year of head-started Black-tailed Godwits

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Head-started bird from 2017

As I write this, the Scientific & Technical Advisory Group of Project Godwit is meeting to review progress. They will be learning about the success of the project, which has three aims: to create the best possible habitat for the small (and threatened) population of Limosa Black-tailed Godwits breeding in the East Anglian washes, to provide protection for nesting pairs and to augment chick-production using head-starting. Head-starting involves removing first clutches and hand-rearing chicks before releasing them back to the wild. All of this is set within a rigorous scientific framework, so that the efficacy of head-starting and nest-protection can be carefully evaluated.

Success!

What a year it has been! When I wrote Special Black-tailed Godwits last year, I finished by saying, “Imagine how exciting it will be if one of this year’s head-started birds is found breeding in the Nene or Ouse Washes next year”. Amazingly, nine of the 26 head-started birds from 2017 were back this year and two females definitely had nests, with one fledging a chick, and a further two paired together are suspected to have attempted to nest. From data shared with me by Roos Kentie, this return-rate is comparable to wild-breeding Limosa Black-tailed Godwits in her Dutch study-area.

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Where did the chicks go?

The left-hand map below shows the finding locations of chicks in the period June to September 2017, before they headed south for the winter. There had been a major publicity campaign, asking birdwatchers to look out for these special godwits in East Anglia. The Project Godwit team were pleased to receive news of six birds in Norfolk, Suffolk and Essex. The bird that turned up at Steart Marshes, in Somerset, came as more of a surprise.

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Most limosa Black-tailed Godwits spend the winter in Africa, south of the Sahara, but an increasing number now stay in Portugal and Spain. There is a WaderTales blog about some of the costs and benefits of this new strategy: Should Black-tailed Godwits cross the Sahara? There were no winter sightings of the head-started birds but several popped up again in the spring of 2018, as shown in the right-hand map above. Four birds were seen in Portugal, two in France and one in Belgium. The Belgian sighting was the only unexpected sighting, as discussed in Site-fidelity in Black-tailed Godwits.

What about ‘wild’ birds?

wild mapRSPB scientists have been using colour-rings to follow the movements of Nene and Ouse Washes Black-tailed Godwits since 1999. As you can see, from the map alongside, the pattern of sightings is very similar to the one for the head-started birds, the only difference being a couple of winter reports in Senegal of the same individual and a bird that spends each winter in Portugal. August and September sightings have been in East Anglia, Spain and Portugal, with February and March sightings in Portugal, Spain, France and East Anglia.

As Black-tailed Godwits move north in February and March, they mix with birds of the islandica race which are preparing for the journey to Iceland. There’s a blog about the two subspecies here: Godwits in, Godwits out: Spring-time on the Washes.

Using geolocators

One of the outstanding questions is ‘Do head-started birds migrate in same way and spend the winter in the same places as birds that were raised naturally’. Given that released chicks have generally behaved just like other youngsters, they probably do, but it would be nice to have proof. To provide an answer, geolocators have been attached to the flag-type ring on each of 22 head-started chicks and 20 wild godwits. When they return (and if they can be caught on their nests) these geolocators will be taken off and the data will be downloaded. Keep an eye on the Project Godwit website for new information.

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Newly-tagged adult is released

Geolocators do not only reveal the final destinations of migratory birds, they also provide information about stop-over sites. Given that the limosa species is in serious decline (there’s a blog about the 75% drop in the Dutch population), it is important to understand the habitat requirements and timing of movements during migration. Two adult birds from the Nene have been tracked using geolocators, both of which spent the winter in Senegal.

The class of 2018

morgan 2018

‘Morgan’ is one of the class of 2018. This chick has already been seen in Hampshire and hopefully the geolocator (attached to green flag) will reveal where it spends the winter.

And so to the second year… As you can read here, 2018 was a strange breeding season. It started with a flood and ended with a drought. A total of 55 eggs were taken from the Nene Washes, including early eggs that had to be rescued from a waterlogged wheat field. Despite the muddy state of many of the eggs, 38 chicks were reared successfully and the first five were spotted away from the Welney and Nene release areas before the end of July – four on the North Norfolk coast and one at Titchfield Haven, in Hampshire.

These sightings and all the others that will hopefully be reported in August and September, are really valuable. They confirm which birds have survived their first few weeks and months in the wild and give a good clue as to which birds the team might see next spring. If you see one of the young birds, which carry a lime E ring on the right leg, please report it via this website.

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Funding

Project Godwit is a partnership between RSPB and WWT, with major funding from the EU Life Nature Programme, The HSBC 150th Anniversary Fund, Natural England, the Heritage Lottery Fund, through the Back from the Brink Programme and Leica UK.


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.

 

 

Site-fidelity in Black-tailed Godwits

Shorebirds are generally philopatric (site-faithful to breeding areas) – youngsters settle to breed in areas near where they were raised and adults don’t move far in subsequent years. What happens to this process when a species is expanding its range or if chicks are reared away from their parents?

Successful head-starting

In a recent trial, to see if head-starting might help to secure the future of limosa Black-tailed Godwits in the Washes of Eastern England, one of the questions to be answered was “would youngsters reared in captivity be able to gather all of the information they need to return to the same area to breed?”

blog nestEggs collected from nests on the RSPB’s Nene Washes nature reserve were taken to the WWT’s facilities at Welney, about 35 kilometres away, to be head-started. Here, the eggs were hatched and the chicks were raised in captivity. As they got bigger, the birds were colour-ringed and moved into a large pre-release cage before being given their freedom, when old enough to fly. With 26 successful head-started chicks, this process added far more young Black-tailed Godwits to the local population than birds in the wild could manage, subject as they were to predation and to flooding of nests. You can read more on the Project Godwit website and in this WaderTales blog Special Black-tailed Godwits.

Limosa Black-tailed Godwits migrate south for the winter, most flying to countries such as Senegal in West Africa but with an increasing number short-stopping in Spain and Portugal. (There’s a blog about the wisdom of crossing the Sahara).

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In this picture of three head-started chicks, Remi is the chick on the right

As birds moved north in the spring, Project Godwit staff were on the look-out for the previous year’s chicks. They were overjoyed when the first of these appeared at Welney, as had been hoped and might be expected, but puzzled when the second was sighted in Doel, near Antwerp in Belgium, showing signs of pairing with what was assumed to be a local, unringed male. So, what had happened to site-fidelity? Why had this colour-ringed female, named Remi, decided to settle over 300 km away? What are the implications for the project to boost the East Anglian population?

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Sites mentioned in this blog. Remi was collected (as an egg) in the Nene Washes, raised at Welney and turned up next spring in Doel, Belgium. Friesland is Roos Kentie’s study area (see below).

Philopatry in Black-tailed Godwits

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Manea – all grown up and back on the Ouse Washes

The head-starting team had been fairly confident that site-fidelity would ensure that head-started birds would recruit locally, as long as the hand-rearing process did not mess with the innate processes that initiated recruitment.

A paper based on ringing recoveries of the limosa subspecies in The Netherlands, published in 1998 by Kruk et al, suggested that young Black-tailed Godwits tend to settle to breed close to where they previously fledged, with most moving no further than 6 km and no appreciable difference between the sexes.

Natal philopatry in the Black‐tailed Godwit L. limosa limosa and its possible implications for conservation, Ringing & Migration, 19:1, 13-16, DOI: 10.1080/03078698.1998.9674156

godwit spread

The expanding range of breeding Black-tailed Godwits within Iceland

In Iceland, where the islandica population of Black-tailed Godwits breeds, colour-ringing of chicks has also allowed dispersal patterns to be measured. Here, youngsters of the islandica race are still pretty site-faithful but there are appreciable differences between the two sexes, with some females dispersing far more than males. In their paper published in 2011, Tómas Gunnarsson et al found that males dispersed an average of 2.3 km (with a range of distances of 0.5 to 7 km) and females dispersed an average of 48 km (with a range of 1 to 204 km). As has been discussed in a previous WaderTales blog, Icelandic Black-tailed Godwit numbers have been increasing for a century, with birds moving into new breeding areas further away from the heartlands of the south coast. Dispersal is a necessary part of the expansion process. There’s more detail here:

Rapid changes in phenotype distribution during range expansion in a migratory bird. Proc. Royal Soc. B, 279:1727 (2011). DOI: 10.1098/rspb.2011.0939

postThe conservation problems being faced by limosa Black-tailed Godwits have spawned a lot of recent research in The Netherlands and along the subspecies’ annual migration route (see Dutch Black-tailed Godwit numbers down by nearly 75%, for instance). In a recent paper, Roos Kentie showed that three-quarters of the adults in her Friesland study site in The Netherlands breed within 500 m of their previous nest site, with a maximum movement of 15 km. Having successfully fledged and migrated south and then north, new recruits settled within 18 km. As in the previous paper about the limosa subspecies, there was no discernible difference between the distances moved by males and females, but there were differences in mean dispersal distances of youngsters raised in different habitats. Birds hatched on grass monocultures moved about twice as far as those from herb-rich meadows, but the mean distances were only 915 m and 1700 m for the two habitats. Young birds moved at a higher rate from the predominant monocultures to meadows than the other way around.

Age-dependent dispersal and habitat choice in black-tailed godwits across a mosaic of traditional and modern grassland habitats Journal of Avian Biology 45: 396–405 (2014). DOI: 10.1111/jav.00273

If limosa Black-tailed Godwits recruit to local sites then what was Remi, the head-started bird from the Washes of eastern England, doing in Belgium? Does this failure to be site-faithful impact upon the conservation programme that aims to boost local populations through hand-rearing and releasing chicks?

Back to the Belgian defector

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Protecting nesting waders by setting up electric fences

By early May, five of the Project Godwit head-started Black-tailed Godwits (three males and two females) had been seen on the Ouse Washes, at Welney and other sites. This was excellent news and in line with what might be expected, given that the Dutch study has shown that only 30% of recruitment is in the first summer, with most birds not starting to breed until their second year. No birds had returned to the Nene Washes, where these eggs had been laid. In terms of site-fidelity, this is what had been expected. It was great news; head-starting works and can give a conservation boost for the species in areas where insufficient young are produced to maintain local populations. It may therefore be possible to reintroduce (or even introduce) Black-tailed Godwits to suitable sites, simply by releasing hand-reared fledglings when they are ready for their independence.

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The Nene Washes

And then came number six. On 6 May, another of the ringed, head-started birds was seen on the Nene Washes, just a short distance from where the eggs had been collected. She was ‘home’ but did not know it, having been transported 35 km to Welney when in the egg. Amazingly, this bird turned out to be Remi, the female that had been consorting with a male in Belgium three weeks earlier. She was with an unringed male, a bird that members of the Project Godwit team felt looked ill-at-ease, not as accepting of their vehicles as were local birds. Perhaps Remi had acquired her mate in Belgium and brought him with her to England? If so, wouldn’t that be a result – this head-started Black-tailed Godwit had not only returned to breed but she might also have brought an extra bird with her!

Remi's chicks

In terms of site-fidelity, Remi fits with the patterns discussed above; she has not moved very far from the site she knew as a fledgling, as suggested by the studies of limosa birds, but she has dispersed further than any of the males, in line with the islandica study. It will be interesting to see what happens to subsequent groups of head-started birds.

** Fantastic update from Project Godwit **

“Delighted to share news that Remi, released last year at WWT Welney, now has chicks of her own at RSPB Nene Washes! Godwits don’t usually breed in their first year and we hope this is the first of many” 14 June 2018

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For the latest news of the head-starting project, check out projectgodwit.org.uk or follow @projectgodwit on Twitter.


 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

 

 

Curlew Moon

In deference to the scientific papers that underpin them, stories in previous WaderTales blogs are expressed in facts and correlations, not emotions. This blog, which is in part a review of Curlew Moon by Mary Colwell, is a little more personal.

Curlew Moon – a special book

book coverCurlew Moon, is based upon Mary Colwell’s walk from the West of Ireland to the East of England, raising money for the BirdWatch Ireland, BTO, RSPB and GWCT Curlew appeals and researching material for the book. She takes the reader into the stripped-bare peat bogs of central Ireland, shares the excitement of feeling the beating heart of a newly-ringed Curlew and meets some great people who care about Curlews in their own, local patches. The book is a fascinating blend of Curlews, agricultural history, culture and poetry – written beautifully.

Global problems

blog flightCurlews are large waders that live long lives. The family to which they belong, the Numeniini, is not coping well with the speed with which the world is changing. Two species of curlew are probably extinct – functionally if not actually – and the godwit members of the family are faring little better. The blog Why are we losing our large waders? summarises an excellent review by the BTO’s James Pierce-Higgins and colleagues from thirty other organisations/institutions around the world. In it, they assess the stresses that humans are imposing upon curlews & godwits, through direct activities and the impact we all have on the climate. It’s not just our Eurasian Curlew that we need to worry about.

British breeders and foreign visitors

Mary’s walk from west to east began on 21 April 2016, so the bulk of her story focuses upon the Curlew breeding season. The book, however, starts with a couple of trips to see flocks that consist mostly of wintering birds, in Norfolk and the Moray Firth.

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The Wash estuary, the bite out of the east coast of England, between Lincolnshire and Norfolk, holds up to a quarter of a million waders in some months, with a peak annual count of 8,000 or so Curlew. Mary went to Snettisham to see some of these Curlews for herself. Most of the birds had crossed the North Sea in the autumn, from countries such as Finland, Germany and even Russia. There are British-bred birds here too but these are in a minority. The WaderTales blog Is the Curlew really near-threatened? is also rooted in Norfolk. If a Curlew can live for 32 years and there are flocks of 1000 in Norfolk, why are they red-listed as a species of conservation concern?

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Tagging a Curlew: Mary Colwell, with Ron Summers of the Highland Ringing Group

Mary’s next trip was to the Moray Firth, where she met up with members of the Highland Ringing Group. Here, Bob Swann and his colleagues caught eight Curlew, in a mixed cannon-net catch of waders and gulls. I love the way that the strange activities of these dedicated, well-trained volunteers are described! The Curlews were all fitted with geolocators, to track their movements over the next twelve months. A previous bird had revealed a fascinating journey to Sweden and back, with only 53 days on her breeding grounds. She spends by far the largest part of each year in Scotland. What will these new birds tell us about the lives of our largest waders?

Habitat and predators

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An Irish marsh, freshly prepared for the peat-cutting machines

The long walk started in Ireland, where breeding Curlew are closest to extinction. In the Irish Republic, the latest survey revealed a breeding population of 124 pairs, down from perhaps 4,000 pairs in the 1980s. I had read about the causes of the demise of the Irish Curlew but Curlew Moon helped me to understand them. I could hear the silence that made an old man cry, I could see the rows of peat-devouring machines and I could understand the impact of changing farming methods. There may have been economic benefits (for some), associated with funding from the EU and the cessation of the Northern Ireland troubles, but Curlews have not been able to keep up with the changes that prosperity has delivered.

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Curlew nest, tucked away in some long grass

The situation is not dissimilar on the other side of the Irish Sea. In a paper reviewing associations between Curlew numbers in Britain and changes that may be causing them, Sam Franks and BTO and RSPB colleagues conclude that Curlew are less numerous and have shown greater population declines in areas with more arable farming, woodland cover and higher generalist predator abundance. Putting it simply, the key thing that conservationists should focus on are “habitat restoration and reducing the negative impacts of predators”. There’s more about this in Curlews can’t wait for a treatment plan.

blog chickIn the book, Mary describes the disappointments experienced by the Curlew Country team in Shropshire; in the years 2015 and 2016, 32 nesting attempts yielded no fledged chicks. Foxes were the main problem – with additional pressure from other predators and farm machinery. There was better news in 2017, perhaps associated with more fox control; three chicks were raised naturally and others were head-started. By taking ten eggs at the point of laying, replacing them with dummy eggs, and switching again at the point of hatching, the team increased the total number of fledged chicks to eight. After two blank years, this was an encouraging success for the team.

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Grouse

Much has been written about grouse moors and waders. As Mary moved on towards the Staffordshire Moors and then The Peak District she knew that she would “come face-to-face with some of nature conservation’s most bitter conflicts”.

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Curlew, nesting in the short grass on a grouse moor

I shall not attempt to summarise the Curlews and Controversy chapter – read it for yourself – but Mary, who describes herself as “left-wing, vegetarian with vegan tendencies” and who has never even held a gun, found more Curlew on a grouse moor she visited in early April than anywhere on her walk.

By removing predators, burning heather to encourage new growth and keeping trees at bay, shooting estates create habitat that is good for both Red Grouse and Curlew. It also suits Hen Harriers which feed on the youngsters of both species. And that’s when the potential for conflict really starts!

One of the arguments in favour of grouse shoots is a financial one. If there is no shooting, land-owners are going to want a return on their investments and an obvious replacement is serried rows of non-native forestry. This will not only take away moorland but will also have effects beyond the woodland edges, due to the actual and perceived risks of predation.

Making space

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Mary with Neal Warnock of RSPB Northern Ireland

There are conversations to be had about how space can be made for Curlews in upland farms and moors, while enabling these areas to be farmed profitably, or at least without loss. As Mary points out, if one farmer is being compensated for managing land in ways that suit breeding waders, the chance of success becomes vanishingly small if a neighbour receives subsidies to grow carbon-capturing trees. How can we ensure that planners understand the bigger picture?

Curlews need plenty of space and three WaderTales blogs talk about how farming and habitat heterogeneity might be impacting upon their success.

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Rachel Taylor, downloading data from a tracking station

In Curlew Moon, Mary writes about a day in Migneint moor, which lies to the south of Mynydd Hiraethog (mentioned above). Here, she and Rachel Taylor of BTO Cymru went in search of tagged Curlews that are contributing to a study Rachel is running with Steve Dodd of the RSPB. Four males have revealed the scale at which the species operates – “One bird flew a staggering 21 km away to a favoured feeding spot”. A paper in Wader Study by Steven Ewing and colleagues suggests that birds are highly variable in the way they use the landscape; two of their males travelling 1.6 km each evening but one bird staying close to the nest. Curlews need more space than perhaps we appreciated.

The people who care

In researching for her new book, Mary Colwell seems to have learnt as much about the people who study and love Curlew as she has about these special birds.  From her close encounters with cannon-netters, using geolocators to chart Curlews’ movements, through to gamekeepers who control predators, Tom Orde-Powlett managing a grouse shoot and others who are improving breeding habitats and monitoring nesting success, she focuses upon the respect so many people have for this fast-disappearing species. At the same time, she shares her own passion for this emblematic bird, the haunting calls of which echo across too many abandoned moors.

The Book

Curlew Moon is published by William Collins. ISBN 978-0-00-824105-6

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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

 

 

Scottish Wader Woes

The 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%

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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

 

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