In amongst the tidewrack

Double-banded Plover

Tidewrack has an image problem. Who wants to see a dark line of seaweed on a beach of white sand or to smell rotting beds of kelp in enclosed bays? Shorebird conservationists may understand the feeding opportunities that are provided by fresh and older seaweed but, for tourist boards, tidewrack is something that needs to be cleared away.

It turns out that tidewrack is not just a biodiverse habitat; the mere presence of seaweed creates spaces in which waders can roost and find shelter. In a paper in the Journal of Applied Ecology, Timothy Davis & Gunnar Keppel get down to Turnstone-level, to investigate the important microhabitats within different forms of beach-cast wrack.

An Australian autumn

Readers in the northern hemisphere may well have seen wintering waders sheltering in the lee of clumps of tidewrack, as a gale blows snow and sand across a beach. At Danger Point, about half-way between Melbourne and Adelaide on the coast of Australia, conditions are somewhat different, with December and January temperatures topping 30°C, conditions in which waders must try to avoid over-heating. By April, when the Davis & Keppel study was carried out, conditions were autumnal, with cool mornings. Three of the species that might be seen on a European beach were present – Turnstone, Sanderling and Bar-tailed Godwit – but with the addition of Curlew Sandpipers and Red-necked Stints, that were about to depart for Siberia, and Double-banded Plovers that breed in New Zealand.

Which looks best – a barren beach or one strewn with seaweed?

What might waders be looking for?

Red-necked Stints

The research team was interested in the range of microclimates available on beaches with beach-cast wrack, to investigate the link between microclimates and microhabitats and how they are used  by waders. They expected to find warmer temperatures and higher humidity on aged wrack, due to advanced decomposition, and ameliorated conditions where wrack deposits provided shelter from prevailing winds. They predicted that waders would use microclimates that could reduce energy loss.

Observations

Data on temperature and humidity were collected by creating miniature Stevenson Screens – hollow white practice golf balls with iButtons inside them, attached to short bamboo canes, so as to be 10 cm above the substrate surface. If interested in conducting this sort of study, it would be sensible to read the methods section of the paper. Sample points were on bare sand, in areas with fresh wrack deposited on the sand and in beds of old tidewrack. Based on surrounding features and observations of prevailing winds, sample points were classified as sheltered or exposed.

Instantaneous scan sampling was used to classify migratory shorebird behaviour for the entire Danger Point study area (i.e., the area over which the microsensors were placed) at 15 min intervals on four days during April, as birds were preparing to migrate. Birds were classified as roosting (loafing, sleeping or preening) or as foraging on one of the three substrate types.

Variability of microclimate

As expected, there were significant differences among the three substrates (sand, fresh wrack and aged wrack) for mean, maximum and minimum temperature and absolute humidity. The temperature above the surface of aged wrack was consistently higher than elsewhere, with one notable exception: in the early mornings, when newly deposited seaweed retained some of the heat from the warmer ocean, temperatures were warmer on fresh wrack than on sand and aged wrack. For aged wrack, humidity was highest above deeper beds.

Curlew Sandpipers on the tide-edge

Bird Behaviour

Six species of wader were studied and included in ‘all waders’ counts but there were insufficient sightings of Bar-tailed Godwit, Curlew Sandpiper, Ruddy Turnstone and Sanderling for separate analyses. The main focus was upon Red-necked Stint (64.0% of observations) and Double-banded Plover (31.4%).

Double-banded Plover sheltered by tidewrack
  • Roosting birds were recorded on aged wrack 16 times more frequently than sand, and three times more than on fresh wrack.
  • Foraging birds were observed more than four times as often on aged wrack, when compared to fresh wrack or sand.
  • However, roosting on fresh wrack was more frequent in cooler, early-morning temperatures, for all waders and for the Double-banded Plover, when considered separately. Neither temperature nor absolute humidity were significant predictors of the proportion of Red-necked Stints roosting in areas with fresh wrack.
  • Foraging by waders (in general) and Double-banded Plover (in particular) was also more common within fresh deposits of wrack when temperatures were low and particularly if humidity was high. For Red-necked Stint, temperature alone predicted whether they were more likely to feed on fresh wrack, rather than aged wrack.

The importance of microhabitats

The authors show that sandy beaches with beach-cast wrack provide a complex mosaic of microclimates/habitats across differing substrates. Birds seem to exploit the microclimatic variation by using microhabitats that minimise energy expenditure, as both foraging and roosting were most likely to occur on the substrate providing the warmest, most energy-efficient conditions at the time.

There is well-documented evidence that food availability increases as seaweed decays, because wrack-beds provide homes for invertebrates, particularly developing larvae. This explains a predominance of foraging on aged wrack, which is likely to provide the best feeding opportunities. The key finding in this study is that tidewrack on sandy beaches provides important additional benefits for waders, by providing shelter and warmth. This may be particularly important when birds are fattening up for the next leg of a migratory journey. It is particularly interesting that, early in the morning, Double-banded Plovers and Red-necked Stints foraged within fresh wrack, the warmest available substrate at that time. Perhaps the effect of microclimate (temperature, humidity & shelter) might be usefully studied in other circumstances in which waders feed and roost?

The bigger picture

Turnstone, Sanderling, Purple Sandpipers and Dunlin on an Icelandic beach, having just crossed the Atlantic

When considering the role that coastal ecosystems play in the lives of waders, the main conservation focus has been on estuaries, as for instance discussed in Wader declines in the shrinking Yellow Sea. The open coastline is under threat too, squeezed by rising sea levels, battered by more frequent storms, polluted by plastic etc. In some areas, waders that use these habitats outside the breeding season are also prone to human (and canine) disturbance, as described in this Turnstone study.

Alongside more general habitat degradation, there are specific threats to tidewrack habitats along the coastline. This starts offshore, with the harvesting of stands of growing kelp, and continues when fresh tide-wrack is collected or cleared from shorelines. In 2018, it is estimated that 15,000,000 tonnes of brown algae were removed, globally. Traditionally, rotted tidewrack has been used as a fertiliser on nearby fields but most of the current output is collected when fresh and used to produce alginates, for food manufacture and biomedical purposes. Increasingly, attention is turning to use in biofuels, which has the potential to greatly increase the demand for seaweed.

Ringed Plovers in amongst seaweed on a Northumberland beach (UK)

Whilst the food, biomedical and energy industries see value in tidewrack, the tourist industry appears to see it as an untidy nuisance that spoils the image of a pristine beach. Who knows how much tidewrack is removed from beaches during daily grooming sessions or dug out of wader-rich corners before the start of the tourist season? If the image of what constitutes a welcoming beach is to be changed then perhaps there needs to be a focus on the interest that seaweed adds to a tideline walk – as visitors collect shells and look for amber, sea-coal and egg-cases. Is this naïve; have cotton buds, bottles and plastic sullied the image of tidewrack? Should we share more photographs of Sanderling chasing through seaweed-flecked spume and flocks of waders ‘chilling’ on banks of beautifully lit seaweed, instead of the barren white beaches that are used in holiday adverts?

As Timothy Davis and Gunnar Keppel conclude: “Beach-cast wrack created a complex mosaic of unique microclimates varying in space and time, which seemingly allowed shorebirds to minimize energy expenditure, by selecting the thermally most favourable habitats for roosting and foraging. Removal of beach-cast wrack therefore reduces habitat quality and increases energy expenditure and resources in shorebirds and may contribute to the observed decline of migratory shorebird species globally. Management of coastal ecosystems and shorebirds therefore needs to maintain fine-scale environmental heterogeneity.”

Paper

Fine-scale environmental heterogeneity is important for conservation management: beach-cast wrack creates important microhabitats for thermoregulation in shorebirds. Timothy John Davis & Gunnar Keppel. Journal of Applied Ecology. April 2021


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

Waders on the coast

The UK’s coastline is of international importance because of the numbers of waders that it supports. In winter it accommodates over a third of Europe’s wintering Oystercatcher, Ringed Plover, Bar-tailed Godwit and Knot, as well as an increasing number of Sanderling.

Wintering waders on the UK’s estuaries are counted every month but those on the 17,000 km of open coast are only counted once a decade. There are good reasons for this disparity, given the much higher development pressures on estuaries and the need for regular monitoring of sites that are designated and protected. However, this does mean that we have very little information about wintering Purple Sandpipers, the vast majority of which are not covered by monthly Wetland Bird Surveys (WeBS). Over three-quarters of the UK’s Ringed Plovers are missed too, along with over half of the Sanderling and Turnstones and nearly half of the Curlew.

The last Non-estuarine Waterbird Survey took place during the winter of 2015/16, as discussed in the WaderTales blog NEWS and Oystercatchers. Jenny Gill and I undertook counts on Great Cumbrae and along stretches of the Clyde coast, in Scotland, an area we had also covered for the 2007/08 survey. We were concerned to count only 84 waders in 2015, compared to 206 in 2006. Details are in the table alongside. We hoped that 900 other people, walking along a total of 9000 km of the UK’s coastline, had been more successful!

The paper summarising NEWS results for the whole of the UK and making comparisons with previous surveys in 1997/98 and 2006/07 was not published until 2021. In the intervening period, the counts were included in two papers about wintering populations of waterbirds in Great Britain and Ireland, that were discussed in Do population estimates matter? and Ireland’s wintering waders. This blog draws heavily on a Twitter thread from the Wetland Bird Survey and the BTO’s press release. The new paper is published in Bird Study.

The big picture

In December 2015 and January 2016, NEWS III volunteers walked along amazing, long, white beaches, surveyed rocky headlands and scrambled the lengths of boulder-strewn coves. Not every kilometre of the coast could be visited but the fact that 50% coverage was achieved meant that estimates could be made of the whole coastline of the United Kingdom, together with the Isle of Man and the Channel Isles.

In terms of absolute numbers, Scotland has consistently supported the majority of the population across all non-estuarine waterbird surveys for Oystercatcher, Ringed Plover, Golden Plover, Lapwing, Purple Sandpiper, Bar-tailed Godwit, Curlew, Redshank and Turnstone. Although this is likely to reflect the relative length of the coastline for Scotland (12,714 km) compared to England (2,705 km), Wales (1,185 km) and Northern Ireland (328 km), Purple Sandpiper, Curlew, Redshank and Turnstone still appear to show a bias towards Scotland.

Using the information collected during the survey, BTO scientists were able to extrapolate estimates of the numbers of open-coast waders in the different countries of the UK and its island dependencies (see table below). The results are published in the journal Bird Study and summarised in the table below.

To evaluate the potential importance of the open coast, NEWS estimates for Great Britain in 2015/16 were compared to average population estimates. For eight species, the open coastline accounts for over 20% of the winter population. The figure of 113% for Purple Sandpipers suggests that more birds may have been present on the coasts of the UK in 2015/16 than in an average year or that the population estimate needs to be revisited. There are no Lapwings or Golden Plover in the table below, as there is no recent, reliable estimate of the national wintering population for either species. The Greenshank line is in italics as the sample size is small.

Ten species are considered in detail in the following sections. The maps were downloaded from the BTO website on 20 March 2021 (https://www.bto.org/our-science/projects/ringing/publications/online-ringing-reports). Comparisons are made between results from the Wetland Bird Survey (WeBS) and the Non-estuarine Waterbirds Survey (NEWS).

Oystercatcher

26% use open coasts. 21% NEWS decline since 1997/98. (WeBS decline 22%).

In December 2015, as we walked around the coast of Great Cumbrae in the Firth of Clyde, pairs of Oystercatchers were already staking out their territories, probably not having travelled anywhere since the previous summer or perhaps even in the last twenty years! Wintering flocks that we saw may well have included breeding birds from inland sites in Scotland, from Iceland and from Norway, together with juveniles and non-breeding sub-adults. NEWS III found that densities of coastal Oystercatchers were highest in Wales but that this is the area in which there had been the biggest declines. Breeding numbers have fallen rapidly in Scotland, as you can read in Oystercatchers: from shingle beach to roof-top.

Lapwing and Golden Plover

There was a 68% drop in Lapwing figures between 1997/98 and 2015/16 and a 59% drop in Golden Plover. NEWS and WeBS counts of Lapwing and Golden Plover are difficult to interpret because birds move readily between the coast and inland fields, in response to local conditions such as lying snow and the wetness of fields. This is further complicated in more prolonged freezing conditions, when flocks of Lapwing fly west and south in search of feeding opportunities.

Grey Plover

3% use open coasts. 71% NEWS decline since 1997/98. (WeBS decline 41%).

The Grey Plovers that we see around the coasts of the UK in December and January breed in Siberia. It has been suggested that one of the reasons for the decline in numbers in Britain & Ireland may be related to new generations of youngsters settling in winter locations on the continental side of the North Sea – a strategy that may now work better, given that winters are not as harsh. It is interesting that losses on open coasts, which many would consider sub-optimal habitats, have been more marked than on estuaries. There’s a WaderTales blog about Grey Plovers.

Ringed Plover

82% use open coasts. 21% NEWS decline since 1997/98. (WeBS decline 47%).

Ringed Plovers are red-listed in the UK because of the decline in winter numbers and the importance of these islands of the hiaticula race. In NEWS III, the vast majority of UK birds were found in Scotland (see earlier table) but densities were highest around the coast of England.  Colour-ring studies in Norfolk showed that breeding individuals can adopt a range of migration plans – some marked birds never left the county and others had winter homes as far away as France, Scotland and Ireland. This dispersal is pretty typical of hiaticula race Ringed Plovers that nest in western Europe and southern Scandinavia. Other races travel very long distances (Well-travelled Ringed Plovers).

Curlew

42% use open coasts. 40% NEWS decline since 1997/98. (WeBS decline 26%).

Large numbers of Curlew arrive in the UK in the autumn, with a strong link between Finland and the estuaries of England and Wales. It is estimated that 20% of Europe’s Curlew winter within the British Isles and any change in numbers has significance for a species that is already listed as near-threatened by BirdLife International. The decline in numbers on open coasts has been greater than that seen in estuaries; it has been suggested that this may relate to the breeding origins of birds using different habitats.

Bar-tailed Godwit

15% use open coasts. 33% NEWS decline since 1997/98. (WeBS decline 21%).

Unlike Black-tailed Godwits, which seek out the gloopiest of mud, Bar-tailed Godwits are perfectly at home on sandy shorelines. Wintering birds are of the race lapponica; these breed in Northern Scandinavia, Finland and western Russia (more here). NEWS III tells us that there has been a larger decline in numbers in coastal areas than on estuaries, perhaps related to the relative suitability of the two habitat types.

Turnstone

68% use open coasts. 29% NEWS decline since 1997/98. (WeBS decline 29%).

Almost all of the UK’s wintering Turnstones are thought to be birds that breed in Greenland and Canada. Declines are consistent between NEWS and WeBS. A Northumberland study has shown that, as numbers have dropped, so birds have withdrawn into areas that are less disturbed by people and dogs (See Disturbed Turnstones). About three-quarters of the UK’s open-coast Turnstones are found in Scotland but they are more thinly spread here than in England.

Sanderling

69% use open coasts. 26% NEWS increase since 1997/98. (WeBS increase 8%).

As discussed in Travel advice for Sanderling, the UK is a pretty good place to spend the winter. Whether the same would have been true for previous generations of Sanderling, that were faced with much colder winters, is open to conjecture. Since 1997/98, the densities of Sanderling in Wales have increased by 712%, by 462% in Scotland and by 85% in England. How long will it be until Sanderling flocks successfully over-winter in Iceland?

Dunlin

6% use open coasts. 51% NEWS decline since 1997/98. (WeBS decline 38%).

Three races of Dunlin can be seen in the UK (as you can read in Which wader, when and why?). Wintering Dunlin are birds of the alpina race, arriving in the UK from Siberia, NW Russia, northern Finland and northern Scandinavia in the late summer. Open coasts around the UK are estimated to accommodate fewer than 20,000 Dunlin. To put this into context, there are six estuaries that each hold more than this total during the winter period.

Purple Sandpiper

Almost all on open coasts. 19% NEWS decline since 1997/98. (WeBS decline 34%).

The rocky coasts of the UK are home to Purple Sandpipers from the Arctic, with a suggestion that North Sea coasts south of Aberdeen mainly play host to birds from Spitsbergen and northern Scandinavia, with Greenland and Canadian birds more likely to be found further north and on the Atlantic coast. Coastal numbers have declined by 19%. The Highland Ringing Group has shown that the number of young Purple Sandpipers has been declining on the Moray Firth, suggesting a period of relatively poor breeding success for birds migrating from the northwest.

Redshank

22% use open coasts. 42% NEWS decline since 1997/98. (WeBS decline 21%).

Perhaps surprisingly, few Redshank cross the North Sea to spend the winter in the UK. Winter flocks are largely made up of home-grown birds and migrants from Iceland. The recent decline in Redshank numbers is thought to be a reflection of changing numbers of British and Irish breeders, although there are no monitoring schemes to provide information about Icelandic birds. Since 1997/98, the number of Redshank on open coasts has dropped by 42% but almost all of the losses have occurred in the period since 2007/08 (37% decline between 2007/08 and 2015/16). Redshank is currently amber-listed in the UK, reflecting falling breeding numbers, but ‘promotion’ to the red list cannot be far off. There is a WaderTales blog about the rapid decline in the number of Redshank breeding on salt-marshes: Redshank – the warden of the marshes.

Summary

The Non-estuarine Waterbird Survey 2015/16 revealed that there have been major declines in abundance of four species since NEWS II in 2007/08, only eight years previously: Lapwing (down 57%), Curlew (down 31%), Redshank (down 37%) and Turnstone (down 32%). Lapwing and Curlew are both red-listed in the UK. The only species to increase is Sanderling (up by 79%).

Given the magnitude of the changes revealed in NEWS III, it is unfortunate that this labour-intensive survey can only be carried out every eight to ten years. Ideally, it might be possible to survey at least a sample of sites on an annual basis. It is certainly to be hoped that funding can be found for NEWS IV within the next few years, and that volunteers will once more be prepared to count waterbirds on beautiful, if exposed, stretches of coastline.

The results of NEWS III are published in a paper in Bird Study:

Wader populations on the United Kingdom’s open coast: results of the 2015/16 Non-Estuarine Waterbird Survey (NEWS-III) and a review of population trends. Humphreys, E.M., Austin, G.E., Frost, T.M., Mellan, H.J., Boersch-Supan, P., Burton, N.H.K. and Balmer, D.E.


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

Travel advice for Sanderling?

blog 9 wint plum ringedHave you ever seen a colour-ringed Sanderling and perhaps wondered why it spends the non-breeding* season on a British or Irish beach rather than on one in Portugal, Ghana or even further south? Why fly from Greenland to Namibia, a distance of over 20,000 km, when spending the winter months in the UK or Ireland requires a flight of as little as 3,700 km? Perhaps the chance of survival is greater in other countries or perhaps birds that travel further have a larger lifetime breeding output? A paper by Jeroen Reneerkens and colleagues provides some of the answers.

*The term non-breeding season (rather than winter season) is used in this blog because Sanderling travelling as far as Namibia experience a southern summer at the same time as UK birds are experiencing a northern winter.

Pros and cons of travelling further?

At the end of the summer, juvenile Sanderling from Greenland start heading south. The first migration might take an individual to Scotland or Namibia, in southern Africa – or anywhere in-between. The circumstances that lead to these initial settlement patterns are unknown but an individual will repeat its first migratory journey every year, with some birds travelling just 7,400 km annually and others travelling over 44,000 km. It has been argued that, for a range of migration strategies to persist, different wintering sites will have balancing pros and cons. This suggests that costs of longer migrations might be matched by benefits gained at the non-breeding destinations. Is this really true?

blog 5 juv Hebrides

Just six weeks after being ringed as a chick, this Sanderling was photographed in Mull (island off the west coast of mainland Scotland)

Using data provided by colour-ring sightings, Jeroen Reneerkens and colleagues assessed three factors that might affect the fitness of individual birds that spend the non-breeding period in different areas.

  • Annual adult survival: If a bird from one non-breeding location is more likely to survive than a bird that spends the non-breeding season somewhere else, it should live longer and potentially have more breeding attempts within a lifetime.
  • Age when a bird makes its first migration northwards: A young individual that flies north in its first spring will potentially have one more breeding opportunity than a bird that remains in the non-breeding area for its first summer.
  • Timing of migration: There is a short breeding window in the High Arctic so a bird that migrates north earlier in the spring may have higher reproductive success, because it will have a higher chance to re-nest if a first clutch is lost. (There is more about this in Time to nest again?)

Studying marked birds

map no arrowsSanderling were captured and ringed in breeding sites in northeast Greenland, at staging areas during migration (SW Iceland, N Scotland and the Dutch Wadden Sea) and in the non-breeding season (Scotland, England, Portugal, Mauritania, Ghana and Namibia). The different analyses in these studies used data from 5,863 Sanderling, of which 5,220 were individually colour-ringed.

Survival rates. By visiting key sites and collating additional reports of ringed birds from hundreds of birdwatchers, the research team were able to estimate the annual survival rates of Sanderling that spent the non-breeding season in England, France, Portugal, Mauritania, Ghana and Namibia. As can be seen in the table, the apparent survival rate in West Africa (Mauritania and Ghana) was much lower than that in Europe or Namibia. A bird with an annual survival rate of 0.75 is 67% more likely to die in any given year than a bird with a survival rate of 0.85. Confidence limits and methodological notes are provided in the paper. There is a WaderTales blog about the importance of measuring survival rates.

sa plus table

Age of first northward migration. The proportion of colour-ringed juveniles that migrated north in the first spring varied significantly, with virtually all Portuguese and English juveniles migrating north but only 35.8 % of those from Ghana and 9.6 % of those from Mauritania. (There were insufficient data to work out figures for Scotland, France and Namibia).

Timing of northward migration. Observations in Iceland provided information on the timing of migration of Sanderling from a range of non-breeding locations. This is the last possible stop-over site on northward migration, before birds migrate to their Arctic breeding sites in Greenland or Ellesmere Island in Canada. Birds from Ghana were observed in Iceland between 5 and 9 days later and those from Mauritania between 10 to 13 days later than the birds from Europe or Namibia. That is a considerable difference, given the short breeding period.

blog 4 Iceland

Flock of summer plumage Sanderling, on migration in Iceland

Summary

The authors asked the question “is there equal fitness throughout the non-breeding range?”, as inferred from the three measured discussed above. The answer seems to be “no”. Sanderling from non-breeding areas in West Africa had lower annual adult survival, delayed first northward migration and later passage through Iceland than birds wintering either further north or south.

map cross Africa

Sanderling travelling north from Namibia do so by crossing the Sahara (generalised route – sample tracks are shown in paper)

Using geolocators**, the team was able to show that birds from Namibia bypassed potential staging sites in West Africa on the way north, flying north across the African continent to Europe, with some birds stopping briefly in the central part of the Mediterranean before spending a longer stop-over in NW Europe, thereby overtaking the Sanderling from West Africa. Namibian individuals used both Mauritania and Ghana as staging areas during southward migration.

** The use of geolocators is discussed in this blog.

The West African sites seem to be relatively poor places in which to spend the non-breeding months of the year. Food availability in spring is likely to be the chief problem. Theunis Piersma and colleagues have shown that the quality and biomass of prey available to shorebirds is lowest close to the equator, resulting in low fuelling rates and low body masses at departure for northward migration in Knot (Piersma et al. 2005).

Sanderling occupy a variety of different and widely-dispersed non-breeding sites between the northern tip of Scotland and the southern tip of the African continent. Here, they experience very different conditions which affect potential, life-time breeding outputs. Sites which appear to be poorer continue to be used, even though there are better options elsewhere, simply because individual birds have no knowledge of other potential areas where they could spend the non-breeding months.

A roll of the dice?

Once a juvenile Sanderling has settled upon a particular migration strategy and a spot in which to spend the non-breeding season, he or she will continue on the same annual cycle for the rest of his/her life. One of the big unknowns for waders/shorebirds – and for other groups of migrant birds for that matter – is just how these settlement patterns develop. (See Generational Change to read how young birds can create new patterns of migration).

Checking their data, Jeroen and his colleagues could see no pattern in the juvenile/adult proportions, sex ratios or sizes of the birds in different non-breeding areas that would help to explain differences in fitness. Birds from the same breeding areas of Greenland end up in non-breeding locations along the whole north-south range. It is almost as if the dice are rolled and a juvenile ends up where chance events take it.

blog 2 flying

At the level of the individual:

  • A Sanderling that spends the non-breeding season in Ghana does not know that it would have a better annual survival rate and be likely to return earlier to Greenland each spring had it ended up wintering in England or travelled as far as Namibia.
  • A bird in Namibia has no idea that it could have saved itself an accumulated migration distance of 37,000 km each year by stopping in England, without affecting its probability of survival.
  • A first-year bird that spends its first potential breeding season feeding on the beaches of Mauritania, will be unaware that first-years from Portugal have all travelled north to Greenland.

blog 8 look for crIt’s amazing what colour-ring readers have helped to discover but there is much still to learn about the migration strategies of individual waders.

Let’s hope that birdwatchers will continue to look out for colour-rings, as flocks of Sanderling chase the waves in and out on beaches throughout the world.

 

Paper in Journal of Animal Ecology

Low fitness at low latitudes: wintering in the tropics increases migratory delays and mortality rates in an arctic- breeding shorebird

Jeroen Reneerkens, Tom S. L. Versluijs, Theunis Piersma, José A. Alves, Mark Boorman, Colin Corse, Olivier Gilg, Gunnar Thor Hallgrimsson, Johannes Lang, Bob Loos, Yaa  Ntiamoa-Baidu, Alfred A. Nuoh, Peter M. Potts, Job ten Horn & Tamar Lok.

blog 6 run for it


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.