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.

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Starting moult early

In waders (shorebirds), the main moult (molt) usually takes place after the migration that follows the breeding season. Golden Plovers adopt a different strategy, starting wing moult while still nesting. Given that these adult birds are not going to fly anywhere any time soon, this seems like a very efficient strategy. So, why do Icelandic and Scandinavian Golden Plovers moult differently? Is this a reflection of available resources?

The post-breeding moult

MOULT CYCLEMoult is an energetic process, especially the post-breeding moult, which includes a change of all of the wing and tail feathers. To complete the whole process, birds ideally need to find a three-month period when resources are good, climatic conditions are benign and there is no need to migrate. For birds on the East Atlantic Flyway that spend the non-breeding season in Europe, moult typically takes place after the breeding season and before days get shorter and the weather gets colder.

One place with plenty of food-rich mud is the Wash, in eastern England. Here, up to 300,000 waders gather each autumn, including Knot from Greenland and Canada, Grey Plover from Siberia and Curlew from countries such as Finland. A relatively small proportion are juveniles, which will only moult their body feathers, but there are probably at least 200,000 waders in full moult at this time of year – dropping and growing a grand total of perhaps a billion feathers between them. Some populations use the Wash as a feeding station, before moving on to moult in their wintering grounds, but this is a minority. This group includes taymyrensis Bar-tailed Godwits (more about these birds here) and schinzii Dunlin, which will travel further south, to Africa.

wing moult

Golden Plovers start their moult during or before the incubation period

There are Golden Plovers spread across the autumn mud-flats of the Wash too, made up of a mixture of birds that have bred in Britain, Europe, Scandinavia and Iceland. Although they end up in the same winter flocks, their moult strategies are different. Recent research by Paula Machín and colleagues has focused upon how breeding season conditions impact upon the moult strategy of two distinct Golden Plover populations, birds breeding in Scandinavia and Northern Russia and others breeding in Iceland. The resulting paper is published in the Journal of Avian Biology.

Conditions at the breeding grounds and migration strategy shape different moult patterns of two populations of Eurasian golden plover Pluvialis apricaria Paula Machín, Magdalena Remisiewicz, Juan Fernández-Elipe, Joop Jukema & Raymond H.G. Klaassen

Icelandic Golden Plovers

scopeUp to one million Golden Plovers arrive in Iceland each spring, mainly from Ireland and western parts of the United Kingdom. This is estimated to be nearly half of the European breeding population. Iceland might seem small, when compared to the vast land-mass of the European continent, but it’s a haven for waders. This status is threatened by the spread and intensification of lowland farming, increased afforestation and by the ‘summer cottage’ industry – but those are stories for another day.

eggsThe Heiðlóa (Golden Plover) is a welcome sight and sound at the end of the Icelandic winter. The first migrants appear about 23 March and nesting can commence as early as 26 April. The usual clutch size is four eggs, with both parents sharing incubation duties. Some first nests are lost, due to predation, but females can lay another clutch. Joop Jukema studied Golden Plovers nesting near Selfoss in the Southern Lowlands of Iceland, timing his captures of nesting birds to coincide with the later part of the incubation period. He was able to assess the progress of moult by scoring the growth of the primary feathers and to work out when each bird would have dropped its first primary. The estimated mean start date of primary moult for males was 19 May (95% confidence interval 27 April – 10 June) with females starting an average of 9 days later, on 28 May (95% confidence interval 6 May – 19 June). On average, males started to moult their primary feathers nine days before the start of incubation, while females started to moult at the same time as incubation began. Potentially, hormone changes associated with the stage of the breeding season could be linked to the onset of moult.

moult graphic

Icelandic Golden Plovers complete their moult prior to departure from the country. By making catches of birds in late August and early September, it was possible to show that the primary moult period is about 100 days. No birds were caught in suspended moult, strongly suggesting that Icelandic Golden Plovers do not attempt to cross the Atlantic before they have attained a complete, fresh set of feathers.

Swedish Golden Plovers

Paula Machín’s main study site was in Ammarnäs in Sweden, on roughly the same latitude as Selfoss and hence with the same amount of daylight. Ammarnäs is colder in spring than Selfoss, not benefiting from the warmer waters of the Gulf Stream which wash the shores of southern Iceland. The average start of incubation in Ammarnäs was eight days later than in Selfoss with the commencement of moult being seventeen days later. Males started primary moult three days after the start of incubation, with females starting twelve days into incubation. It is interesting to note that the difference in timing of the two sexes is nine days, just as in Iceland.

chickFemale Golden Plovers left the Ammarnäs breeding territories at the end of July. From observations of females caught on their nests, it seemed likely that individual females were not starting the moult of their outer primaries, typically completing the moult of primary four and not dropping primary five. Males stayed with chicks for an extra fortnight. Given the longer period of time available to males, it is likely that they were able to moult more primary feathers than their partners, prior to departure from the area.

Catching birds during the chick-guarding phase or just before migration is very difficult but Raymond Klasssen and colleagues were able to study birds on similar strategies by catching birds at Lund, in southern Sweden, and in the Netherlands. Here, birds from Swedish breeding areas and further afield gather to moult, recommencing primary moult at the point at which it had been suspended. Inspecting moulting birds in the period August through to November enabled the research team to monitor the second part of the moult of Continental birds. Given that the distance between breeding areas and these staging areas is relatively short and that tracking showed that it could be completed in one or two days, it is possible that adults might be able to migrate while in active moult.

Spot the difference

measuringOverlapping the breeding and moulting period is rare in migratory birds but it makes sense in a time-constrained annual cycle. The research team suggest that Icelandic plovers presumably need to initiate moult early in the season, in order to be able to complete it at the breeding grounds. This is not an option for Continental plovers, as their breeding season is much shorter, due to a harsher climate and an earlier drop-off in the number of arthropods, their main food source. These Golden Plovers cannot delay the start of the moult period until after the autumn migration because there is insufficient time to compete a full moult in areas such as Lund or the Netherlands, prior to the onset of winter frosts. The fact that Golden Plover are largely associated with farmland, rather than estuarine sites, may make them more susceptible to sub-zero temperatures than, for instance Grey Plover.

When incubating and looking after chicks, Icelandic and Swedish Golden Plovers were able to moult at the same rate. However, there were differences in the second part of the primary moult season. Away from their territories, Icelandic birds continued to moult at the same rate as previously but, having moved to Lund or the Netherlands, Continental birds could moult twice as fast as before. The availability of earthworms in these staging areas may make it easier to acquire resources for the energetically-expensive moult process.

TGG flying

Despite the faster rate of moult of Continental birds in the later period of their moult, the total period of primary moult is longer than that of Icelandic birds. Birds completing their moult in Iceland took an average of 100 days to replace their primaries, whilst Swedish-breeding birds took 16 days longer. This difference may be associated with the time taken to complete the first stage of moult, prior to the migratory flight away from the breeding sites.

alarmA key finding of this paper is that splitting the moult period extends the total period of primary moult. For Swedish breeders, this is the best option, however, as there is insufficient time to complete autumn moult close to the breeding grounds or after the breeding season. As the authors conclude, “Meeting the energy demands of breeding, moult, and migration calls for different timing and spacing of these events in their annual cycle, adjusted to conditions at their breeding and stopover sites, and to their migration strategy.”

There’s more from Paula Machín and her colleagues on this blog-site: https://overthetreeline.wordpress.com/

More moult

There are more WaderTales blogs about moult: 

  • The not-so Grey Plover includes general information about wader moult and talks about some of the stresses that may occur.
  • Lapwings can moult while on migration. Read more in Lapwing Moult, which also talks about how to study moult without catching birds.
  • Bar-tailed Godwit; migration and survival mentions the different strategies of two subspecies of Bar-tailed Godwit, both of which can be found on the Wash in autumn.

I look forward to future papers about moult strategies to add to WaderTales. Here’s a list of the 60+ blogs that are already available: https://wadertales.wordpress.com/about/

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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

blog Morticia

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.

Earith 2

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.

headstarted map

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.

Mark release

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.

 

 

Black-tailed Godwit and Curlew in France

In July 2018 there was a call for people to express their opinions on the issue of hunting Black-tailed Godwits and Curlews in France. This blog aimed to bring together some background to inform the discussion. The outcome of the review is now printed at the bottom of this blog.

Problems for large waders

Oct 2017The Numeniini is the group of waders that includes curlews, godwits and the Upland Sandpiper. Globally this group is under threat – two species of curlew are probably already extinct. These long-lived species are threatened by pressures during the breeding season and, in some parts of the world, reduced annual survival.

Click here to read a blog about the threats to large waders.

Conservation of migratory species

The Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) is an intergovernmental treaty dedicated to the conservation of migratory waterbirds and their habitats across Africa, Europe, the Middle East, Central Asia, Greenland and the Canadian Archipelago.

Developed under the framework of the Convention on Migratory Species (CMS) and administered by the United Nations Environment Programme (UNEP), AEWA brings together countries and the wider international conservation community in an effort to establish coordinated conservation and management of migratory waterbirds throughout their entire migratory range.

Eurasian Curlew

RC picEurasian Curlews are listed as Near-Threatened by BirdLife/IUCN. Shooting of this species has ceased in western Europe, apart from France. A moratorium (pause) was put in place in France in 2008 but that was amended in 2012 to allow shooting on the coast, which is where many of the Curlews are to be found. Shooting of Curlews ceased in Great Britain in 1981, in Northern Ireland in 2011 and Ireland in 2012. The partial moratorium in France was due to come to an end on 31 July 2018. Opinions were sought as to whether there should be a one-year extension.

LPO (Ligue pour la Protection des Oiseaux), the BirdLife International partner in France, argued that shooting of Curlew should cease or at least that that there should be another moratorium, for at least three years, covering coastal as well as inland areas.

Jan 2018 extinction riskAn AEWA (Agreement on the Conservation of African-Eurasian Migratory Waterbirds) plan of 2015 called for an immediate end to hunting and for an Adaptive Harvest Management process to be set up to recommend if any hunting could be sustained. Continuedcurlews in france shooting in France must surely be in contravention of the international plan? Here’s a link to the AEWA Action Pan for Eurasian Curlew.

Tens of thousands of Curlew spend the winter in France, migrating here from across Northern Europe. The purple dots on the map alongside represent the recovery locations of Curlew ringed in Britain and Ireland. Many of these ringed birds have been found in breeding areas, especially Finland, but there are plenty of reports in coastal France, most of which are birds that have been shot.

Click here to read a blog explaining why we should be worried about Curlews.

Black-tailed Godwit

subspeciesTwo subspecies of Black-tailed Godwit spend time on French estuaries; limosa and islandica. The size of the islandica subspecies is increasing, as the breeding range in Iceland expands (blog about this) but the number of limosa is in rapid decline. Limosa birds that spend time in France breed in the Netherlands and surrounding countries, including a small number that breed in the washes of East Anglia. You can read about the 75% decline in the Dutch breeding population in this blog.

Picture7Agreements signed by partners of AEWA and members of the European Union included a five-year moratorium (pause) in shooting of Black-tailed Godwits in the whole of France. This was extended for a further five years, up until 31 December 2018.

It is hard (or even impossible) to separate islandica from limosa Back-tailed Godwits and we know that they occur in mixed flocks. Scientists have been colour-marking Black-tailed Godwits of both subspecies for many years and birdwatchers can help to assess the relative threat to limosa by reporting colour-ring sightings. You can read more about the value of colour-ring sightings here:

Godwits & Godwiteers 

Project Godwit

blog ManeaBlack-tailed Godwit is still on the French quarry list but there is an ongoing hunting moratorium (pause) that, as for inland Curlew, ends on 31 July 2018. Opinions are being sought as to whether there should be a one-year extension.

LPO argued that, given that it is not possible to distinguish the two subspecies, Black-tailed Godwit should be removed from the quarry list or, alternatively, that there should at least be another moratorium (of at least three years).

Result of the consultation

A decision has been made that nothing should change. There will be a complete ban on the hunting of Black-tailed Godwit in France until 30 July 2019 and permission has been granted to continue to hunt coastal Curlew. Link here.

 


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.

Fewer Spotted Redshanks

blog stalkingIt’s usually a good day if you see a Spotted Redshank in Britain or Ireland. How about a flock of 60?

On 27 July 1975, I was fortunate to be part of a Wash Wader Ringing Group cannon-netting team that caught 60 Spotted Redshanks at Terrington, on the Lincolnshire border of Norfolk. When we fired the nets, we knew that there were some Spotted Redshanks in the catching area but, as these birds were part of a mixed catch of 414, most of which were Redshank and Dunlin, the total number of these elegant ‘shanks came as a very welcome surprise. Why so many, what did we learn about Spotted Redshanks and what do we know now?

How to catch Spotted Redshanks

blog water groupThe spring of 1975 was very wet in East Anglia, with twice the annual monthly rain as is normal in April. Pools formed in fields, seed failed to germinate and there were many bare patches in cereal crops. Rather than leave a muddy pool to bake in the summer sun, a tidy-minded Terrington farmer decided to cultivate a strip through the corner of one of his fields, very close to the sea-wall. Conveniently, he created an area that was just the right width in which to set cannon-nets, meaning that any birds that chose to roost on the bare part of the field over high-tide were almost bound to get caught. It is unlikely that we missed many other Spotted Redshanks when we caught our 60.

This was actually the second catching attempt on the site. Two weeks earlier, on the previous set of spring tides, we had caught 460 birds in two catches – mostly Dunlin and Redshank but with one Spotted Redshank. In the previous 15 years, WWRG had caught just two Spotted Redshanks but more than 4000 Redshanks. Across the whole of Britain & Ireland, between 1909 and 1974, a grand total of 169 Spotted Redshanks had been ringed, which again puts the figure of 60 into perspective.

Where did they go?

The Spotted Redshanks we see in Britain & Ireland are assumed to breed in boggy woodlands in northern Scandinavia and Russia but there are no recoveries of ringed birds to prove this. Prior to the Terrington catch, there had been two foreign recoveries of BTO-ringed birds. A bird caught in Essex in August 1963 was caught by a Dutch ringer in May 1967, presumably on spring passage. Another, caught in July 1966 in Kent, was shot in Malta in April 1968, on its way back from an unknown wintering location in Africa.

blog swimmingThere have been two foreign recoveries of the Terrington birds, caught on 27 July 1975; amazingly both were in Morocco. The first was shot in March 1976, perhaps on its way north, but the second, shot in January 1983, may well have been wintering in North Africa. There has been one other foreign recovery of a WWRG since 1975; a bird ringed by WWRG in August 1978 was shot in Italy in March 1979, presumably on spring migration. This was the only Spotted Redshank ringed by WWRG in 1978. Six Spotted Redshanks have been recovered in France since 1975.

According to the 2016 BTO Ringing Report, a total of four foreign-ringed birds have been found in the UK. Two Dutch birds have been found dead at Hayling Island, Hampshire (January) and Tetney Lock, Lincolnshire (January) and a third (colour-ringed) bird was present at Titchwell, Norfolk in the summers of 2013 and 2016. A bird ringed in Germany on 10 August 1972 was recaught by ringers at Eyebrook Reservoir, Rutland, 23 days later.

The Terrington-ringed bird shot in Morocco in 1983 still represents the BTO longevity record for the species (7 years 5 months 16 days); this is similar to records set by Finnish and Dutch ringed birds. (There is a WaderTales blog about longevity in waders here)

Summering Shanks?

Many of the Spotted Redshanks we caught on the Wash in 1975 were thought, at the time, to be summering, first-year birds but these were in the days before the publication of the Guide to the identification and ageing of Holarctic Waders (Prater, Marchant & Vuorinen, BTO) and I do wonder whether early onset of moult may have led to some ageing errors. We now know that females can moult very early, having left their partners to finish brooding their eggs and bring up the chicks. Some of their moult can take place near their breeding grounds, which could mean half-summer plumage birds arriving in July. Alternatively, birds could have arrived in June and already be in moult. Had the wader guide been available in 1975, we might have been able to separate out full-plumage males and females by looking at the central under-tail coverts and the edges of the head feathers. Next time …

blog BirdTrackThe latest BirdTrack graph gives pretty clear evidence that there is a gap between the end of spring migration and the start of autumn passage. However, as you can see, it’s short; just the end of May and the start of June. It has been suggested that not all first-year Spotted Redshanks travel to the breeding grounds, with some staying in their wintering grounds and others completing only part of the journey north. The few birds that are still in the UK in the May/June gap could be some of these one-year-old individuals or full adults not in condition to breed.

Looking at numbers

blog booksAs I prepared for this article, I turned to Twitter to see how unusual the Terrington catch had been, simply in terms of the number of birds counted in flocks. There have been some recent largish counts, including one of 52 at Old Hall Marshes (Essex) in September 2017 and 32 at Blacktoft Sands in Yorkshire in 2015 but, interestingly, I learnt that bigger flocks were mostly historical. According to the three books, The Birds of Norfolk, Suffolk & Essex, the three peak counts have been 187 at Snettisham in 1977, 112 at Minsmere in 1991 and 127 on the River Colne in 1972.  Mike Wilkinson remembers a flock of 100 at Elmley (Kent) in 1988.

This story from Northumbrian Birds illustrates a typical recent trend. Here, the record counts were of 27 and 21 at Lindisfarne in 1974 and 1976 but there has been a maximum count of just 7 in the last ten years. At the other end of England, Steve Rogers reported that he had 45 at Ruan Laniholme in Cornwall in 1977 but that “you’ll be lucky to see one” now. This is just a small selection of the comments received from a wide spread of  places, including Poole Harbour in Dorset and Cork in Ireland.

blog WeBSPotentially, the development of new nature reserves around the coast and along our river valleys might have created new opportunities for Spotted Redshanks, with birds spreading out across more sites and hence in lower concentrations? To get a national viewpoint, I turned to the online report from the monthly Wetland Bird Survey (WeBS). What did winter counts by volunteers from across the United Kingdom tell us about what has been happening to the species over the period since 1975? As you can see from the graph alongside, the index has dropped by 50% since the start of this century, in line with the local information for late-summer passage discussed above. (There is a WaderTales blog about WeBS here).

Conservation concerns

According to the BirdLife International species fact-sheet, as downloaded from http://www.birdlife.org on 25/07/2018, Spotted Redshanks are of ‘Least Concern’, largely because the large breeding and wintering ranges (map below) reduces the risk of extinction. Breeding numbers are hard to monitor, due to the low densities in the wooded marshes near the tundra edge, and the series of winter wader counts for the UK is much longer and more comprehensive than any other country in the wintering range. Perhaps there would be more concern if there were other international counts that showed the same sort of declines as seen in the UK?

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BoCC4Here, Spotted Redshank is listed as amber, rather than green, simply because the estimated winter count of about 100 is large in a western European context. Perhaps a decline of 50% should create pressure to change amber to red or, more importantly, to revisit the ‘Least Concern’ designation. Whilst it might be hard to target conservation action at a species which uses such a wide range of breeding, passage and winter locations, perhaps we should acknowledge that, according to what is probably the best evidence available, we are seeing a rapid decline?

Our catch of 60 Spotted Redshanks in 1975 is an amazing memory but concentrations in these numbers could be found at a number of sites on the east coast between at least 1964 and the end of the 20th Century. For the moment, we must acknowledge that UK autumn flocks of 60 are largely a thing of the past. Perhaps flocks of 30 might soon be consigned to history? Keep counting!

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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

 

Mission Impossible? Counting Iceland’s wintering Oystercatchers

If Norwegian Oystercatchers migrate south and west for the winter, how is it that thousands of Oystercatchers can adopt a stay-at-home strategy in Iceland, which lies at a higher latitude than most of Norway?

Braving the cold

As part of a project to try to understand why some Oystercatchers spend the winter in Iceland, when most fly south across the Atlantic, researchers needed to count the ones that remain. Unlike in the UK, where the Wetland Bird Survey can rely on over 3000 volunteers to make monthly counts of waders and waterfowl, it’s tough to organise coordinated counts of waders in Iceland. Winter weather, a small pool of birdwatchers and short days don’t help when you are trying to cover the coastline of a country the size of England.

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Up until 2016, the only winter wader data in Iceland came from Christmas Bird Counts, first run in 1956. These coordinated counts suggested that most Oystercatchers were to be found in southwest and west Iceland, which is also where most birdwatchers live, but with smaller numbers in areas such as the southeast. The maximum number of Oystercatchers found in any one year was 4466 birds but this excluded known wintering sites which were inaccessible or very hard to access. Some contributors to Christmas bird counts live in areas away from the well-populated west of the country, and they provided evidence that there were no Oystercatchers in the north, for instance. This information gave some guidance as to where to look for Oystercatcher flocks but could a small team of researchers and birdwatchers do a complete count of the resident component of the species in the middle of winter?

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Part one of the survey involved a group of well-prepared birdwatchers and researchers spending several days counting Oystercatchers in as many areas as possible of the southeast and in the whole of the west, from the southwest tip of Iceland (where Keflavik airport is situated) through to known wintering locations in the northwest fjords. The north and south coasts could largely be discounted; the north is too cold and the south coast is very barren.

Part two of the survey was carried out by air, allowing the addition of counts of the islands and inaccessible coastal sites in the Breiðafjörður Bay, as well as some key sites in Faxaflói Bay (see map). Flocks of roosting Oystercatchers were usually seen from afar and photographs were used to make counts without flushing the birds.

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Survey results

The ground-based wader surveys were carried out between 28 January and 3 February 2017 and the aerial survey took place on 16 February. In total, 11,141 Oystercatchers were counted, which nearly triples the previous Christmas total. As expected, the vast majority of Oystercatchers were found on wintering sites in SW and W Iceland. Large numbers of birds were found on sites not covered by the Christmas counts, particularly on the north side of Faxaflói Bay and during the aerial survey over Breiðafjörður Bay.

blog BoddiThe full results of the paper are presented in a new paper in the BTO journal Bird Study. (Click on title for link)

Population size of Oystercatchers Haematopus ostralegus wintering in Iceland Böðvar Þórisson, Verónica Méndez , José A. Alves, Jennifer A. Gill , Kristinn H. Skarphéðinsson, Svenja N.V. Auhage, Sölvi R. Vignisson, Guðmundur Ö. Benediktsson, Brynjúlfur Brynjólfsson, Cristian Gallo, Hafdís Sturlaugsdóttir, Páll Leifsson & Tómas G. Gunnarsson.

Resident or migrant? 

One of the key questions that researchers wanted to answer was ‘what proportion of the Icelandic breeding population is migratory?’ This is part of a bigger project exploring the causes and consequences of individual migratory strategies, as you can read in the previous WaderTales blog: Migratory decisions for Icelandic Oystercatchers. This project is a joint initiative by the universities of Iceland, East Anglia and Aveiro, led by Verónica Méndez.

blog familyIn order to estimate the proportion of migrants and residents it was necessary first to determine the total size of the Icelandic Oystercatcher population, based on a recent estimate of 13 thousand breeding pairs (Skarphéðinsson et al. 2016) . How many sub-adults are there to add to the 26,000 breeding birds?

Verónica Méndez and her team have shown that Oystercatchers fledge on average about 0.5 chicks per pair. Using estimates that 50% of these chicks are alive by mid-winter, that there is then a 90% chance of annual survival and birds typically breed when they are four years old, it was possible to come up with a total population of just over 37,000 birds.

Although the authors of the paper have produced the best winter estimate thus far, they note that it is a minimum – there could be small numbers of birds in other areas. At 11,141 out of 37,177 birds, the minimum estimate of the residential part of the population is 30%, leaving 70% to be distributed around the coasts of the British Isles and (in smaller numbers) along the coastline of mainland Europe.

Latitudinal expectation 

blog ringed birdTo put the migratory status of the Icelandic Oystercatcher into context with other Oystercatcher populations breeding in NW Europe, the authors collated information about the proportion of resident and migratory Oystercatchers in coastal countries between Norway and the Netherlands. They show that there is a strong latitudinal decline in residency. From Northern Norway (69.6°N) to Southern Sweden (57.7°N), where mean January temperatures are typically in the range of -1 to -4°C, only occasional individuals are found in winter, whereas populations in Denmark (55.4°N), where mean January temperatures 0.8°C, and sites that are further south and warmer mostly comprise resident individuals.

blog scenicThis cline in migratory tendency is also seen within the British Isles, which stretch from 60.8°N to 50.2°N. Writing in the BTO’s Migration Atlas, Humphrey Sitters reports that birds from the north of the British Isles have a median recovery distance of 213.5 km, whereas in the west, east, south and Ireland the respective figures are 35.5, 27.0, 6.0 and 13.5 km. In each group, there are birds that travel over 800 km, implying some degree of migratory tendency in birds breeding in every part of the British Isles.

Iceland lies between 63.2°N and 66.3°N, which puts it well within the latitudinal range of the ‘almost-all-migrate’ group of Scandinavian birds. The Icelandic proportion of 30% residency is likely to be a function of the temperature and geographical isolation of the island. Bathed by the relatively warm waters of the Gulf Stream, some coastal areas, particularly in the west of Iceland, provide a relatively mild oceanic climate and apparently ample food stocks to support high survival during most winters. On the other hand, days are very short. For an Oystercatcher that spends December in Reykjavik, the time between sunrise and sunset is just four hours and the average January temperature is -0.6°C. For a bird in Dublin day-length figure is almost twice as long, at seven and a half hours, and temperature is 5.3°C. Food availability may well be compromised by the time available to collect it, as previous studies have shown that feeding efficiency is on average lower at night.

blog of other wadertalesIceland might hold a higher proportion of residents than would otherwise be the case as it is far enough away from Britain (about 750 km to mainland Scotland) and Ireland for the sea crossing to potentially be a significant barrier. For migrants, time will need to be spent acquiring the reserves needed for the journey south in the autumn and north in the spring and the flights may well add costs in terms of survival probability.

There is a blog about the broader project to understand how individual birds become ‘programmed’ to be migrants or residents here: Migratory decisions for Icelandic Oystercatchers.

The migration option 

blog sightingsIf 30% of Oystercatchers are staying in Iceland this implies that up to 26,000 birds of Icelandic origin are to be found in the British Isles and on the western coast of Europe during the winter. Some of these – young birds that are yet to breed – can be found in these areas in the summer too. By the end of the summer of 2017, Verónica Méndez and her team had colour-ringed about 800 (500 adults, 300 juvenile) birds in Iceland, in order to try better to understand the reasons for the migratory/residency decisions that individuals make. Every dot on the map alongside (which was created on 1st June 2018) represents a migratory bird. Each record is valuable and there are lots more birds to try to find! Are there really no Icelandic Oystercatchers in the vast flocks of eastern England?

If you come across a colour-marked Oystercatcher, please report it to icelandwader@gmail.com 

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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.

 

 

 

 

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

blog Manea

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

blog cables

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