Nesting Temminck’s Stint – the smallest of the 22 wader species for which trends are reported
At the end of the summer, vast numbers of waders leave Norway, Sweden and Finland, heading southwest, south and south-east for the winter. In a 2019 paper by Lindström et al, we learn what is happening to these populations of Fennoscandian breeding species, as diverse as Temminck’s Stint and Curlew. The news for the period 2006 through to 2018 is basically pretty good – most populations have been stable and there are even some that have increased – but there are worrying signs for Broad-billed Sandpiper, Red-necked Phalarope and Whimbrel.
Breeding waders of Fennoscandia
As a volunteer taking part in the Breeding Bird Survey (BTO/JNCC/RSPB) in the UK, I feel that I do my bit to monitor what is happening to local bird population – providing counts that build into national trends. The work involved in delivering indices for breeding waders across the area of Fennoscandia shown in the map is in a different league. Here, counters visit habitats as diverse as forests, wetlands, mires and tundra, within the boreal and arctic areas of Norway, Sweden and Finland. Some survey sites are so remote that access requires the use of helicopters.
Fennoscandia provides important breeding areas for a large set of wader species, and models suggest that these habitats may be particularly vulnerable to climate change, especially increasing summer temperatures. The 2006-18 analysis in Wader Study, the journal of the International Wader Study Group, presents population trends for 22 wader species. The trends are based on 1,505 unique routes (6–8 km long), distributed over an area that’s about four times that of the United Kingdom.
The surveys took place across the whole of Norway and Finland, and in the northern two thirds of Sweden, between 58°N and 71°N, which largely coincides with the boreal, montane and arctic regions of Fennoscandia. The systematic distribution of these routes ensures that the main habitats in these countries are sampled in proportion to the area they cover. The paper describes the methodologies used in the three countries and the way that data were combined, especially factors used to translate sightings of individuals into ‘pair-equivalents’.
Overview of results
Looking at the results from across Norway, Sweden & Finland:
- In terms of pure numbers, Golden Plover was the most commonly encountered wader species, followed by Wood Sandpiper, Snipe, Greenshank and Green Sandpiper.
- The five most widespread species, seen on the highest number of routes, were Snipe, Green Sandpiper, Greenshank, Wood Sandpiper and Common Sandpiper.
- Wader species richness and the total number of wader pairs were both higher with increasing latitude; the median number of wader pairs per 10 km increased from just below 3 at latitudes 58–60°N, to just above 26 at latitudes 69–71°N.
- Using a multi-species indicator, the research team found no general change in wader numbers over the period 2006-18.
- The trends were significantly negative for three species: Red-necked Phalarope (-7.9% per year), Broad-billed Sandpiper (-5.4% per year) and Whimbrel (-1.3% per year).
- The trends were significantly positive for three species: Oystercatcher (+4.9% per year), Dunlin (+4.2% per year) and Wood Sandpiper (+0.8% per year).
- There was no significant trend for another 16 species for which encounters were deemed to be frequent enough for analysis.
- Population trends of long-distance migrants tended to be more negative than those of medium-distance migrants. This is discussed in detail in the paper.
Focusing on some key species
The Lindström et al paper is a tremendously rich source of information and references. Here are some species-specific highlights.
Oystercatcher. In the context of a species that is declining across NW Europe, the fact that there is a significant increase in Oystercatchers across Fennoscandia may be surprising. However, the authors note that there was a jump in numbers between 2006 and 2007 with little change since then.
Lapwing. The trends within the three Fennoscandian countries are very different. In Norway, there has been a dramatic decline (-15.2% per year during 2006–2018) and the Lapwing is now nearly extinct in many areas. The trend in Sweden is also significantly negative (-5.8% per year). In Finland, however, where the species is more widespread and numerous, there has been a strong increase (+5.9% per year) during the same period. See figure alongside.
Golden Plover. No significant change overall. There are some country-specific differences in trends, with a moderate decline in Norway being countered by a moderate increase in Sweden.
Snipe. The overall trend of this species for each country indicates an initial decline followed by an increase. A similar pattern has been noted in the UK’s Breeding Bird Survey over the same period.
Nesting Whimbrel
Woodcock. The trend for 2006–2018 is basically stable and similar in all three countries.
Curlew. There is no significant trend, overall, but populations in Norway and Sweden have declined at the same time that numbers in Finland have increased.
Whimbrel. Fennoscandian trend indicates a decline of 1.3 % per year. Whimbrel is doing poorly in Norway and Sweden but better in Finland.
Wood Sandpiper. This widespread species has increased slowly (0.8% per year), a trend that is largely driven by Norwegian and Swedish populations.
Wood Sandpiper was the second most commonly encountered wader
Redshank. The fact that no change was discernible, suggests that boreal and arctic populations are faring much better than the breeding populations further south in Europe. For example, see Redshank – warden of the marsh.
Redshank – more obvious than most breeding waders encountered!
Spotted Redshank. The estimated annual decline for Spotted Redshank is 2.8% per year but the species is too thinly spread for this to provide significant evidence of a decline. This rate is very similar to the recent drop in the Wetland Bird Survey index in the UK. See Fewer Spotted Redshanks.
Broad-billed Sandpiper. This species has the second most negative trend among the 22 species analysed (-5.6% per year). The bulk of information comes from Finland where the trend is even more negative (-7.5% per year). Birds head southeast in the autumn to countries bordering the Indian Ocean – areas for which winter trend data are not available. The species is still considered to be of ‘least concern’ but perhaps this designation may need to be revisited?
Dunlin. Breeding birds in the survey area are largely of the alpina race. The overall trend is significantly positive (+4.1% per year), which is in sharp contrast to the strong declines of the schinzii subspecies that breeds around the Baltic Sea, western Finland and further south and west in Europe.
Ruff. There were major declines in the period immediately prior to this review (Lindström et al. 2015) but changes reported here are lower (-2.3% per year) and the decline is not statistically significant.
Red-necked Phalarope. The authors write, “This species has the most negative trend of all the 22 species [-7.9% per year], with most data coming from Sweden. We do not know the cause of this decline but, given that this species shares its south-eastern migration route with Broad-billed Sandpiper, whose population exhibits the second largest decline, the relevant problems might largely apply somewhere along the migration routes”.
Link to Britain & Ireland
As shown in Which wader when and why? there are strong migratory connections between Fennoscandia and the British Isles. Some waders, such as Green, Common and Wood Sandpipers, pass through on their way south in the autumn, whilst many more fly here for the winter, to take advantage of the warmer maritime climate.
Three wader species with particularly strong links between Fennoscandia and Britain & Ireland are still shot and eaten in these islands. Each autumn, large numbers of Woodcock, Golden Plover and Snipe cross the North Sea. It is difficult to ascertain figures for the number that are shot but there is agreement that the vast majority are winter visitors, as opposed to native birds. The results presented in the paper suggest that there have been no discernible changes in the Fennoscandian populations of these three game species in the period 2006-18. Two earlier WaderTales blogs focus on Woodcock and Snipe in Britain & Ireland:
There has been no significant change in Golden Plover numbers across Fennoscandia
Two WaderTales blogs about wintering waders in Great Britain and the island of Ireland were published in 2019, based on reviews in British Birds and Irish Birds. These were Do population estimates matter? and Ireland’s wintering waders. The six big losers, in terms of wintering numbers in these islands, were Knot, Oystercatcher, Redshank, Curlew, Grey Plover and Dunlin. Knot arrive from Greenland and Canada, with Grey Plover flying from Russia, but it is interesting to think about this Fennoscandian breeding analysis in the context of winter losses of the other four species.
- Wintering numbers of Oystercatchers have dropped recently in Britain and in Ireland. The population is made up of migrants from Iceland (more about this here), very large numbers from Norway, birds that stay within the British Isles and smaller numbers from other European and Scandinavian countries. Given there is no discernible decline in Fennoscandia, it seems likely that much of the decline can be attributed to a major fall in Scottish breeding numbers (more about this here).
- Most Redshank wintering in Britain & Ireland are of local or Icelandic origin. Fennoscandian numbers seem to be stable; if there were any changes, these would probably not be apparent in wintering numbers within the British Isles.
- The Eurasian Curlew has been classified as ‘near-threatened’ and the species is known to be declining in many areas (see this blog about serious problems in Ireland). Ringing shows a particularly strong link between Finland, where breeding numbers seem to be increasing, and Britain & Ireland. The decline in British and Irish winter numbers is probably being driven by lower breeding numbers within the British Isles and in countries such as Sweden, Norway and Poland.
- There is a theory that new generations of alpina Dunlin may be more likely to winter within Europe’s mainland estuaries, instead of continuing their westward migration across the North Sea. This might explain the apparent anomaly between the 4.1% per annum rise in Fennoscandian numbers and recent winter declines of 3% in Britain and over 20% in Ireland.
Going forwards
Some of the survey areas were in particularly remote areas
Many of the study squares that were covered during these surveys are a long way from the main centres of human population in Norway, Sweden and Finland. The governments of the three countries are to be congratulated for supporting this important monitoring, which relied on the commitment of hundreds of volunteers. It is to be hoped that these surveys will continue and that further species-focused work will be able to explain some of the differences across Fennoscandia, particularly between eastern and western areas. The rapid declines in numbers of two species that migrate southeast each autumn (Broad-billed Sandpiper and Red-necked Phalarope) highlights the need for better information about what is happening on the flyway linking Fennoscandia with the Arabian Sea and coastal countries of the Indian Ocean.
Paper
Population trends of waders on their boreal and arctic breeding grounds in northern Europe: Åke Lindström, Martin Green, Magne Husby, John Atle Kålås, Aleksi Lehikoinen & Martin Stjernman. Wader Study 26(3)
Click on the title of paper to access it on the International Wader Study Group website. Paper is only available to members of IWSG. If you have read the whole of this blog you’ll probably want to join!
Nesting Bar-tailed Godwit in smart summer plumage
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.
One or two WaderTales blogs are published each month. The series is UK-based with a global reach. Suggestions of newly-published research on waders that might be of interest to birdwatchers who appreciate waders/shorebirds are welcomed. I am particularly keen to give feedback to colour-ring readers; they provide a huge amount of information that lies at the heart of these stories.
Ken Smith, Mike Reed and Barry Trevis have been studying a colour-ringed population of Green Sandpipers in Hertfordshire (an English county just north of London) since 1983. The focal point of their activities is Lemsford Spring, a Hertfordshire & Middlesex Wildlife Trust nature reserve. The site is a set of disused watercress beds that provide plenty of freshwater shrimp (Gammarus pulex) in shallow lagoons fed by freshwater springs. Over the years they have been able to use their colour-ringed birds to study return rates from year to year, behaviour and local habitat use. Using radio-tags they have looked at nocturnal activity patterns and more recently they have been using GPS geolocators to find where their birds go to breed.
The highest numbers of Green Sandpipers in southern England occur in late summer, when many passage birds pass through the country, but a few birds stay for the whole winter. The Lemsford studies show that colour-ringed birds have a high return rate from one winter to the next. These birds are actually in the general area of Lemsford for most of the year, only leaving to breed for two or three months. Upon return, in late summer, they use other local sites such as gravel pits, only switching to the watercress beds in the autumn.
Once established in the Hertfordshire area, individual Green Sandpipers were likely to turn up in subsequent winters, with little difference in return-rates between young birds, ringed in their first winter, and adults. There was considerable variation from year to year, with the return rates varying from 68.7 to 100%; the lowest being between 1986/87 and 1987/88, when another local winter site (Cole Green) became unsuitable. Birds using that site presumably went elsewhere or died. The average apparent annual survival rate was 83.5% (or 84.7% if account is taken of the disappearance of Cole Green). In the only other similar study, in northern Germany, the mean return rate was only 56%, with few birds returning in the year after a severe winter. In the Hertfordshire study, there is a correlation between the overall return rate of colour ringed birds from one winter to the next and the number of nights with air frost in the first winter (r = -0.86, n = 7, P < 0.05). These results suggest that birds suffer increased mortality in severe winters.
From observations at Lemsford, it appears that, once territories have been established, local birds are well aware of their boundaries and neighbours. Should a bird stray into a neighbouring bird’s patch, a low-key call is sufficient warning to avoid a disagreement. Ken reports that the big disputes, with chasing and out-and-out aggression, only occur when the territories are being established or when a new bird tries to feed in an established territory. During extremely cold weather, in the 1980s, there would be lots of extra birds attempting to feed in the spring-fed watercress beds, by trying to squeeze into perceived gaps between territories. Such cold conditions are very rare nowadays.
In recent years, the research team have deployed harness-mounted geolocators to ascertain the movements of a small number of individuals during the course of a full annual cycle. Another WaderTales blog discusses migration and the effects of harnesses on the behaviour of individuals. See 
According to 
Lemsford 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:
Although 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.
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