Not-so-Common Sandpipers

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

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

Common or Spotted?

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

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

Population changes

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

Breeding season

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

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

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

The southward migration

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

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

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

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

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

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Life in the south

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

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

The northward migration

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

Why so few Common Sandpipers?

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

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

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

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

Common & Spotted Sandpipers

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

Book Details

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

New research

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

t.mondain-monval@lancaster.ac.uk


GFA in Iceland

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

@grahamfappleton

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From local warming to range expansion

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

Setting the scene

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

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

A booming population

godwit spread

Expanding breeding range in Iceland

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

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

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

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

Catch your godwits

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

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

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

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

Major Findings

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

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

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

Are these findings applicable to other species?

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

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

Paper

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

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Juveniles gather together in the late summer, prior to departure


GFA in Iceland

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

 

Iceland to Africa, non-stop

blog tagRinging had already suggested that Whimbrel might fly non-stop from Iceland to western Africa (see “Whimbrels on the move”). By using geolocators, Camilo Carneiro and his colleagues from the Universities of Iceland and Aveiro (Portugal) have now shown that this is the norm – and reveal just how quickly they get there.  In the paper reporting on this work, they contrast this rapid autumn movement with what happens on the return journey in spring.

Migratory journeys

European Whimbrel are made up of two distinct populations which mix in the wintering grounds. Three-quarters of the estimated total of 400,000 pairs breed in Iceland, with the rest breeding from Scandinavia through to Russia. In the autumn, most of the Icelandic birds fly straight to Africa. In the late summer and early autumn, the vast majority of birds seen in the UK and other European countries on the East-Atlantic Flyway are of continental (rather than Icelandic) origin. Most will continue their migrations to Africa.

Camilo Carneiro’s paper focuses on the Icelandic population. Although the breeding locations of the birds in the study all fell within a circle of radius 5 km, the wintering area represents about 1500 km of the coastal strip of western Africa and its off-shore islands. This includes Sierra Leone, Guinea-Conakry, Guinea-Bissau, Senegal, The Gambia, Mauritania and Morocco, with the highest density of the locations in Guinea-Conakry and Guinea-Bissau. On spring migration, although some manage a similar non-stop flight, most birds stopped off on their way back to Iceland. The largest number paused in Ireland, with others visiting western Britain, northwest France and Portugal. Marked birds flew an average of 6079 km in autumn and 6450 km in spring.

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A sense of urgency

Most studies show that birds migrate faster in spring than in autumn, something that may be associated with a need to get to breeding sites as quickly as possible. Potentially, this enables them to take advantage of the short window in which to find a partner, lay and hatch eggs, look after chicks and fatten up for the return journey. Why is autumn migration quicker for Whimbrel that breed in Iceland and spend the winter in countries such as Guinea-Bissau?

blog tag postCamilo Carneiro and his colleagues have been studying the migrations of individual Whimbrels using geolocators. These small devices, attached to leg-rings, record the times of dawn and dusk for twelve months. When (or if!) an individual can be caught again in the subsequent breeding season, the geolocator can be removed and the data down-loaded, revealing a year’s worth of movements. One of the fascinating things about this study is that there are 56 migrations from 19 individuals; meaning that there are several birds for which repeat information has been collected. There’s a WaderTales blog about geolocators here (Are there costs to wearing a geolocator?)

The tags used on these Whimbrels did not just measure light levels, they also recorded temperature and whether the tag was wet or dry. These extra data helped to establish more precisely the periods in which birds were on migration, as air temperature is lower at higher altitudes and tags can only record wetness if birds are standing in water. Please see the paper and supporting materials for details of the methodology. Given that birds cannot fly without fuel, account is taken of the time taken to fatten up for migration, when estimating the whole migratory period.

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Wintering Whimbrel in Guinea-Bissau

Results

The paper by Camilo Carneiro in the Journal of Avian Biology provides details about the wintering and staging location of Icelandic Whimbrel but the main focus is on speed of migration. This was calculated as the ground distance travelled divided by migration duration, where this period includes fuelling time.

  • blog flightAll birds flew directly from Iceland to the wintering sites (30 autumn migrations from 19 individuals), a journey of four or five days.
  • Males departed earlier than females in spring and made a stopover in 83% of the cases (15 out of 18 individuals), while females stopped on 75% occasions (6 out of 8).
  • Migration duration (fuelling plus flight times combined) was significantly different between seasons, being 59.2 ± 6 days in autumn and 65.5 ± 6.2 days in spring, with no apparent differences between sexes.
  • Migration speed and ground speed were higher in autumn than in spring (migration speed: 102.6 ± 2.2 kmd-1 in autumn and 98.6 ± 5.3 kmd-1 in spring; ground speed: 16.50 ± 5.99 ms-1 in autumn and 13.07 ± 5.82 ms-1 in spring), with no differences between sexes.
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Catching an individual Whimbrel, in order to remove its geolocator, becomes harder every year. A range of methods is used to catch birds on their nests.

With only a small sample, the following reported results were not statistically significant:

  • On average, males departed later than females on autumn migration. This makes sense, as males stay with their chicks longer than females.
  • In spring, males arrived into Iceland on average 2 days before females.

Explaining the patterns

The discussion section of the paper provides a fascinating review of some of the theories relating to migration physiology – it’s well worth a read. This is just a quick summary.

Autumn migration seems relatively straightforward; every tracked Whimbrel took a direct flight from Iceland to Africa. For Whimbrel migrating to Iceland from western Africa in spring, however, there seems to be a relatively small chance of being able to fly all the way in one hop (5 out of 26 northward flights were direct). The authors suggest that:

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    Whimbrel roosting in the top of mangroves at high tide

    When leaving Iceland at the end of the summer, Whimbrel are heading towards predictable resources which will be similar from week to week. Timing of departure is not critical and birds may be able to wait for helpful weather patterns.

  • On the journey south, wind conditions are generally more favourable than on the journey north, reducing the duration of direct flight.
  • Some birds may have sufficient resources for the northward flight, if weather conditions are helpful, but choose to stop off in western Europe (particularly Ireland) if the fuel gauge suggests that they might not be able to complete the crossing.
  • It is possible that the relatively recent addition of West African Bloody Cockles to the Whimbrel’s diet, in the Banc d’Arguin, may have improved the species’ capacity to fatten up quickly, increasing the possibility of a one-flight trip north.
  • Staging areas in western Europe, particularly Ireland, may provide relatively predictable resources that can be used to top-up reserves for the final 1500 km crossing of the Atlantic in spring. By using a stop-over, it may be possible to take on extra reserves that can be used in the early part of the breeding season.
  • There may be a stronger link between weather patterns in western Europe and Iceland than between western Africa and Iceland. Whimbrel that stop off in Ireland, or other countries on the Atlantic seaboard, may then depart in weather systems that are also associated with warmers spring conditions in Iceland.

blog no ringThere are many questions still to be answered but one thing is certain; as it says in the title of the paper, when the migration of the Icelandic Whimbrel is studied in detail, it is clear that there is faster migration in autumn than in spring. Here’s a link to the paper:

Faster migration in autumn than in spring: seasonal migration patterns and non‐breeding distribution of Icelandic Whimbrels Numenius phaeopus islandicus Camilo Carneiro, Tómas G. Gunnarsson & José A. Alves Journal of Avian Biology 10.1111/jav.01938

More about migration

Migrating birds make ‘decisions’ on timing and staging each year that can affect their personal survival and the chance of successfully raising young. Are these ‘strategies’ just the consequences of the circumstances that arise in a particular season? As scientists gather longer runs of tracking data on individuals, and can relate these to wind and weather patterns, it may be possible to gain a better understanding of the drivers of migratory patterns.

The team behind this paper (Camilo Carneiro, Tómas Gunnarsson & José Alves) have produced a number of complementary papers on wader migration, some of which have been covered in previous blogs:

WaderTales: Overtaking on Migration.  Alves, J. A., Gunnarsson, T. G., Potts, P. M., Gélinaud, G., Sutherland, W. J. and Gill, J. A. 2012. Overtaking on migration: does longer distance migration always incur a penalty? – Oikos 121: 464–470.

IBIS/BOU: Risking it all in a direct flight.  Alves, J. A., Dias, M. P., Méndez, V., Katrínardóttir, B. and Gunnarsson, T. G. 2016. Very rapid long-distance sea crossing by a migratory bird. – Sci. Rep. 6: 38154.

Gunnarsson, T. G. and Tómasson, G. 2011. Flexibility in spring arrival of migratory birds at northern latitudes under rapid temperature changes. – Bird Study 58: 1–12.

WaderTales: Whimbrels on the move.  Gunnarsson, T. G. and Guðmundsson, G. A. 2016. Migration and non-breeding distribution of Icelandic Whimbrels Numenius phaeopus islandicus as revealed by ringing recoveries. – Wader Study 123: 44–48.

WaderTales: Black-tailed Godwit pairs – the importance of synchrony.  Gunnarsson, T. G., Gill, J. A., Sigurbjornsson, T. and Sutherland, W. J. 2004. Arrival synchrony in migratory birds. – Nature 413: 646.

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The southern lowlands of Iceland (breeding grounds of Whimbrel) seen from Þríhyrningur

 


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.

 

 

 

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.

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.

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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.

 

 

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 bird was present at Titchwell, Norfolk in the summers of 2013 and 2016, where the ring was read in the field. 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).

blog 3 bums

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?

map for blog

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

 

 

Green Sandpipers and Geolocators

In a paper in the BTO journal, Ringing & Migration, Ken Smith and his collaborators review how wearing a tag, attached using a harness, affects the preening and feeding behaviour of Green Sandpipers. What did they find and where do their Hertfordshire birds spend the summer?

The lives of Green Sandpipers

Tom SpellerAccording to BirdLife International’s Data Zone page, there are between 1.2 million and 3.6 million Green Sandpipers across Europe and Asia. The breadth of this estimate reflects the difficulty of assessing the population of a species that breeds in wet forest clearings, from western Norway to about 155 degrees east in Russia. It’s hardly any easier to count them in the winter, sprinkled as there are around small pools, in ditches and along river valleys from West Africa to Japan.

The occasional pair of Green Sandpipers breed in the UK and Population Estimates of Birds in Great Britain and the United Kingdom, published in British Birds by Andy Musgrove at al suggests, that fewer than 1000 birds spend the winter here, although rather more are seen on passage between Scandinavia and Africa. In an ever-changing world, studying populations of a species that is at the edge of its range has the potential to explain patterns of loss (or gain) that are less obvious in the heart of a species’ distribution.

Why use geolocators? 

In a previous blog (Bar-tailed Godwits: migration & survival), it was shown that colour-rings, which enable individual recognition of a bird without capture, provided 30 times as much information about annual survival as a metal ring. Adding a geolocator takes you into a new data-rich environment. A geolocator is a small device that records the location of an animal. By recapturing a bird a year after ringing and downloading these data, important information about the timing of migration, the duration of stop-overs at fuelling sites and the exact breeding and/or wintering location can be ascertained.

One of the important things to appreciate about scientists who study bird migration is that they are as keen as any other birdwatcher to ensure that the tracking devices they use cause as little disturbance to the normal life of their study birds as possible.

Attaching geolocators

light geolocator

Geolocator with a light-stalk

In shorebird research, the most common form of geolocator is one that is attached to a ring on the bird’s leg. For most individuals, these devices do not have any negative effects but for smaller waders there can be some problems. Shorebird ecologists from around the globe cooperated to review these issues , publishing it in Movement Ecology. It is summarised in the WaderTales blog, Are there costs to wearing a geolocator? Hopefully, anyone contemplating a new shorebird study will read these before starting. Any data that are collected are only valuable if the birds are either unaffected by the equipment and attachment methods or, if there are effects, these do not prejudice the scientific integrity of the study or the welfare of the birds.

GPS

GPS geolocator, fitted with elastic loops to form the harness

In this study, the Green Sandpipers were fitted with leg loop harnesses, first described by Rappole and Tipton, the authors having decided that ring-mounted geolocators might be too bulky on such a small wader. These harnesses are looped around the top part of a bird’s legs so that the geolocator sits like a small rucsac on the lower back, nestled in the feathers. In the figure below, the left picture shows a tagged bird; you may just make out a slight lifting of the back feathers over the top of the geolocator light stalk. The right-hand picture has been annotated to show how the ‘rucsac’ is fitted.

annotated

The geolocators and harnesses represented 1.4–1.6% of the body mass of the birds. In the study, two different types of device were used, light-level geolocators and GPS geolocators – see the details in the paper. The effects of tagging on behaviour patterns have been examined and written up as a paper in the BTO journal Ringing & Migration, using data collected from seven Green Sandpipers that were fitted with harnesses.

Feeding and preening behaviour

Ken Smith and his colleagues have been studying the Green Sandpipers wintering at Lemsford Springs Nature Reserve in Hertfordshire, southeast England for over thirty years. These shallow lagoons were previously managed as watercress beds. In this particular investigation, the scientists compared the behaviour patterns of individual birds fitted with geolocators, before and after tagging, with a control group of untagged birds. They were particularly interested in the proportion of time spent feeding and preening. Feeding time was thought to be an indication of normal foraging behaviour and preening would be an indication of any discomfort or unfamiliarity caused by the tags and harnesses.

lemsford

Green Sandpipers spend their time feeding, preening and roosting, with most of the feeding activity occurring in loosely defined territories. Four of the tagged birds could be viewed regularly and their activities were observed alongside seven untagged (but colour-ringed) individuals. The amount of time spent feeding increased as days lengthened in the spring and birds prepared for migration. Previous research has shown that the Green Sandpipers on this site are not constrained by feeding opportunities, except in the coldest of condition. In these latter circumstances birds will also feed at night but normally they only feed during the day.

Investigating tag effects

Picture1Lemsford is a well-watched site. Most birdwatchers couldn’t tell which birds were tagged and which ones were not. The tags were so well preened into the plumage that they were extremely difficult to see, even in high-quality photographs. The tags could only be spotted by experienced observers and tag-effects could only be established using 20,000 minutes of observations. A less-intensive study would have showed no significant effects. These bullet points summarise more detailed findings in the paper:

  • All four tagged birds that were closely observed in this study returned successfully from their breeding areas and three of the tags were retrieved. There were no apparent signs of any problems such as skin abrasion or feather wear, caused by the tags or harnesses, and the birds continued to be observed after their tags were removed. The one bird that evaded capture and whose tag was not retrieved was present throughout the second winter.
  • Within the wider group, eight out of ten birds with tags returned the next winter, which is not significantly different from the overall return rate for untagged birds.
  • Tagged birds spent a small but significantly higher percentage of their time preening than untagged birds (untagged birds 4.6%, tagged birds 6.3%). Comparing the periods immediately before and after tagging for the four tagged birds for which detailed observations were collected, there were no differences in the time spent feeding but a significantly higher proportion of the time was spent preening (rather than just resting).
  • Birds may well get used to their tags over time. Of the three tagged birds for which there was sufficient data, two showed significant declines in the proportion of time spent preening over time (15% down to 5%), whereas one was at 6% throughout.

Where do these Green Sandpipers go?

Colour-ringing at Lemsford had already shown that birds are very site-faithful during the winter, once autumn passage birds have moved through. There’s more about this in a previous paper in Bird StudyHabitat use and site fidelity of Green Sandpipers Tringa ochropus wintering in southern England.

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This map is available from the BTO website

At the time that the Migration Atlas (Movements of the Birds of Britain & Ireland) was written, using data collected between 1909 and 1997, there was only one record of a BTO-ringed bird in its breeding area. That bird was found in Sweden, and there has been one other in Finland since. Green Sandpipers are not easy birds to observe and, although the long-term colour-ringing project at Lemsford Springs has generated large numbers of local re-sightings, there have been none elsewhere. Early results from the geolocator study show that the Lemsford wintering birds breed in Norway (2), Sweden (3) and Finland (1). A paper will be produced once a larger sample of results is available for analysis; it will look at migration strategies as well as breeding locations.

There is a WaderTales blog that summarises migration of over 40 wader species to, from and through Britain & Ireland: Which wader, when and why?

This paper

Neil Beadle - twoAlthough this study has involved small numbers of tagged and untagged birds, it has shown a consistent pattern of increase in the proportion of time spent preening by birds after tagging, with some evidence that this subsequently decreases over time. There is no evidence of an adverse impact on return rates of tagged birds from one winter to the next, although with such small sample sizes only a major change would have been detectable.

This paper is published in the BTO journal, Ringing & Migration:

The effects of leg-loop harnesses and geolocators on the diurnal activity patterns of Green Sandpipers in winter Ken W. Smith, Barry E. Trevis and Mike Reed


 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

 

 

Just one Black-tailed Godwit

When you receive a list of sightings of a colour-ringed bird that you have reported to a scheme organiser, it can hide a wealth of information. Here’s one such bird.

Blue Red – Yellow Green-flag

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BR-YGf photographed in Caithness (north of Scotland) in the spring of 2017

There are some colour-ringed Black-tailed Godwits that have generated two hundred or more sightings at well-watched locations but BR-YGf is more typical. When seen in Cambridgeshire on 26 March 2018, that was only the 12th observation in the database.

The Black-tailed Godwit that was soon to become BR-YGf was wintering in Portugal when caught in a mist net, by José Alves and a team of other ringers, just before dawn on 25 October 2014. It was given a unique set of three colour-rings and a flag, that would enable it to be identified in the field by birdwatchers. Measurements of wing length and bill length, taken at the time, meant that it could be identified as a male, using criteria described in this paper in Bird Study.

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Wader-ringing team in Portugal

Colour-ringing of Black-tailed Godwits started in Portugal in 2006, when José was working on a PhD at the University of East Anglia, in which he studied the ecology of Black-tailed Godwits wintering on the Tagus and Sado Estuaries of Portugal. Colour-ringing has continued since, contributing to coordinated studies of Icelandic Black-tailed Godwits in Spain, Portugal, France, the UK, Ireland and, of course, Iceland.

Breeding in Iceland

Almost all of the islandica Black-tailed Godwits breed in Iceland, with small numbers on the Faeroes, a handful on the Lofoten Islands of Norway and an occasional breeding pair on a Scottish island. Jenny Gill and I saw BR-YGf in the west of Iceland in April 2016, as we checked for marked birds in a flock of 1100 birds, many of which were new arrivals. He was feeding in a newly-ploughed cereal field, that had been previously spread with pig-muck from the neighbouring industrial-scale piggery. We managed to look at 800 pairs of legs in that flock; there was another green-flagged bird from Portugal, two orange-flags from France, a bird from Ireland and three from England.

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The history of BR-YGf since he started wearing coloured rings in 2014

We have been checking flocks of Black-tailed Godwits arriving in Iceland for many years. One of the most significant recent outputs is a paper that explains that young birds, recruiting into the population, are driving the advancing arrival of the species into Iceland in spring. The results are summarised in this blog: Why is spring migration getting earlier?

Autumn moult

Most of the Icelandic Black-tailed Godwits that winter in Portugal stop off to moult en route in autumn. We see some of these birds in the UK but BR-YGf is one that, from the sightings in September 2016, probably moults into winter plumage in France. Moulting is an energetically expensive process; birds that are mid-moult don’t usually migrate so these autumn staging sites are very important to the flocks that use them. When first caught in Portugal, in late October 2014, BR-YGf was in full winter plumage, probably having recently arrived from France.

Spring overtake

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The Samouco salt-pans, where BR-YGf was ringed, with Lisbon in the background

Portugal is a warm place to spend the winter, with relatively long days and plenty of food – very different to the east coast of England, for instance. The only down-side is that Portugal is a long way from Iceland, which you might think leads to later return in the spring. Most Portuguese birds get around this problem by migrating in two legs, the first of which takes them to either the Netherlands or the British Isles. BR-YGf chooses the British option. This blog explains this migratory strategy: Overtaking on migration.

BR-YGf has been spotted in two springs since ringing. On 14 March 2016 he was seen at Old Hall Marshes in Essex by Steve Hunting and on 26 March 2018 he was seen by the Project Godwit team on the Nene Washes in Cambridgeshire. Mark Whiffin and colleagues were looking for limosa subspecies godwits, newly returned from Africa to breed, but their birds were outnumbered by large flocks of islandica, fattening up for the trip north. There’s more about the differences between the two subspecies in Godwits in, godwits out: springtime on the Washes with some hints on distinguishing which subspecies is which.

Portuguese birds, on an earlier migratory schedule, tend to be further ahead, in terms of moult, standing out in their red finery against the greyer local birds, some of which will travel to Iceland up to four weeks later. You can read more about the spring moult in this WaderTales blog: Spring moult in Black-tailed Godwits. Did you know that waders smell different in summer plumage?

Why Caithness?

BR-YGf has been following a well-used migration route: breed in Iceland, moult in France, winter in Portugal, spring in England, back to Iceland and repeat, for perhaps twenty or more years. What was he doing in Caithness, in the very far north of Scotland on 22 April 2017?

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Although the average timing of arrival of individual godwits in Iceland has not changed, the small amount of annual variation in their timings may be related to the weather they encounter en route. In the spring of 2017, we were in Iceland waiting for birds to turn up. The weather was lovely – if cold – but northerly winds appeared to bring a brief halt to most migration. In our two-week stay we saw only 28 colour-ringed Black-tailed Godwits; not quite as bad as the spring of 2013, when winter returned to Europe in April, but close.

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In some years, Black-tailed Godwits, and other waders making the trip to Iceland, may get part way across the Atlantic and have to turn back or they may reach the north of Scotland or the Western Isles and stop. Colour-ring sightings alert colour-ring coordinators to these events, as presented in the blog: Waiting for the wind.

Thank you

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Looking for Black-tailed Godwits in Moita (Portugal) – José Alves, Jenny Gill and me

Thousands of birdwatchers have contributed to the studies of Icelandic Black-tailed Godwits. Every sighting is valuable, especially repeat records from the same site. This WaderTales blog tells the stories of some of the birdwatchers who contribute their sightings to these projects: Godwits and Godwiteers.

It’s great to see old friends, when out ‘godwitting’. Jenny Gill and I have seen BR-YGf in Portugal (2016 & 2017) and in Iceland (2016). We recognised him but he probably will not have recognised us.

Please report any colour-ringed Black-tailed Godwits to j.gill@uea.ac.uk and she will forward them to the appropriate coordinator as necessary. Thank you!


 GFA in Iceland

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

@grahamfappleton

 

International Shorebird Rescue

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

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

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

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

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

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

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

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

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How science can inform policy

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

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

Dutch Black-tailed Godwit numbers down by nearly 75%

Black-tailed Godwits expand their range in Russia and Iceland

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

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

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Fencing – an effective treatment plan?

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

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

How are fences deployed in  lowland wet grassland?

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

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The key role of estuaries

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

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

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

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

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

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

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Spoon-billed Sandpipers – true teamwork

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

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

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

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Shorebird scientists are working with colleagues and policy-makers in China, S Korea and N Korea to save space for Spoon-billed Sandpipers in the Yellow Sea. (A more recent article by Nicola Crockford develops this story in Wader Study:

More game-changing good news on coastal wetland conservation – a policy perspective from the Yellow Sea to global conservation.

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Quick mention of climate change

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

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Notice > Diagnose > Treat

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

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

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

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


 GFA in Iceland

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

@grahamfappleton