How well do Lapwings and Redshanks grow?

There has been an assumption that managers of nature reserves know how to provide the right foraging conditions for Lapwing and Redshank chicks.  This paper in Wader Study shows that they do.

Lapwing chick Andy Hay rspb-images (2)

How quickly will this Lapwing chick grow? Photo: Andy Hay/RSPB images

For conservationists looking to increase wader populations, attracting birds to a chosen site is a good first step, but only if pairs can breed more successfully than they would have done elsewhere.  To understand whether a species recovery prescription works or, if it does not, to understand what is going wrong, it’s necessary to measure nest success, chick growth and fledging rates.  In their paper in the journal Wader Study, Lucy Mason and Jen Smart focus on the middle of these – how well chicks grow – to check whether the right feeding conditions are being provided.

Mason, L.R. and Smart, J. Wader chick condition is not limited by resource availability on wader-friendly lowland wet grassland sites in the UK. Wader Study 122:3 Dec 2015

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Tags make it easier to find ringed Redshanks. Photo: Kirsty Turner

Breeding success for Lapwing and Redshank can be poor, even on protected sites, which often leads site managers and policymakers to ask whether low food availability might be limiting chick survival, despite management aimed at providing optimum foraging conditions. Although this question is difficult to answer on a large scale, Lucy and her team were able to monitor and compare wader chick body condition and rates of growth across a range of UK sites.  If food availability is an issue, they expected to find that chicks would grow slower and weigh less than might be expected – or hoped.

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Photo: Kevin Simmonds

One of the main reasons RSPB scientists published this research was because site managers often ask for support to monitor invertebrates, in order to make sure that there is enough food for waders.  There are lots of reasons why this is extremely difficult – i) what is enough? ii) chicks are catholic in their choice of prey, going for whatever is abundant and available at the time, so what do you measure and when? iii) linking food availability to growth and survival is inevitably tricky.  The great thing about this paper is that it shows that, in general, well-managed sites will provide enough food.  If managers are worried about food availability then monitoring the growth rates of chicks and comparing their data to the published information is far easier than measuring an invertebrate resource that varies hugely in space and time.

To understand the growth rates of Lapwing and Redshank chicks, a total of 130 tags were deployed across 15 lowland wet grassland nature reserves and protected sites, within the UK, during 2009, 2010, 2012 and 2013.  This enabled family parties to be tracked and helped to yield a total of 750 monitored individuals.  All sites were managed with the aim of providing optimum conditions for breeding Lapwing and Redshank (both nesting and chick rearing).  Chicks were ringed, tagged and measured when captured and subsequently about every eight days.  Relocating the chicks involved tracking the tagged individuals and, through them, their ringed siblings.  It was harder to recapture Redshanks, which are more cryptically coloured and move around more.

Lapwing Fledglings

Two well-grown Lapwings on a wet day. Photo: Jen Smart

Lucy and her colleagues demonstrated that, on average, Lapwing and Redshank chicks achieved growth rates similar to those calculated for larger samples of chicks studied in The Netherlands and the UK, and achieved better conditions more quickly than those measured in a standardised Dutch study.  This suggests that food availability for wader chicks on well-managed lowland wet grassland sites is unlikely to be limiting chick survival and population recovery.

To understand why populations of species such as Lapwing and Redshank are failing to recover, the focus should be on other potential causes of chick mortality, such as predation or agricultural activities.  The positive message is that, if these other causes of chick mortality can be reduced, well-managed wader sites are likely to be successful in producing healthy fledglings and to facilitate population recovery.

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Body condition of tagged Lapwing chicks (centre) did not differ from that of untagged chicks in other broods, indicating that the tags (representing 2-3% of a tagged chick) and recapture frequencies did not aversely affect chick body condition or growth. Photo: Jen Smart

More feeding opportunities for chicks

There are several management options which are being used by conservation organisations and land-owners who are keen to try to support species that breed on lowland wet grasslands.  The first suite increases feeding opportunities for chicks:

_DSC2219Redshank

Long grass is important to nesting Redshank and their chicks. Photo Kevin Simmonds

Grazing regimes need to be adjusted to create the correct sward height, heterogeneity of structure etc. See, for instance, McCracken, D. & J. Tallowin. 2004. Swards and structure: the interactions between farming practices and bird food resources in lowland grasslands. Ibis 146: 108–114.

Increasing the height of the water table provides better feeding opportunities for adults and chicks.  See, for instance: Eglington, S.M., M. Bolton, M.A. Smart, W.J. Sutherland, A.R. Watkinson & J.A. Gill. 2010. Managing water levels on wet grasslands to improve foraging conditions for breeding northern lapwing Vanellus vanellus. Journal of Applied Ecology 47: 451–458.

Providing more wet habitat features, in the form of pools or foot-drains. See, for instance: Eglington, S.M., J.A. Gill, M. Bolton, M.A. Smart, W.J.Sutherland & A.R. Watkinson. 2007. Restoration of wet features for breeding waders on lowland wet grassland. Journal of Applied Ecology 45: 305–314 and Smart, J., Gill, J.A., Sutherland, W.J., Watkinson, A.R., 2006. Grassland-breeding waders: identifying key habitat requirements for management. Journal of Applied Ecology 43: 454-463.

Using agri-environment schemes to achieve these habitat goals. See, for instance: Smart, J.A., Wotton, R., Dillon, I.A., Cooke, A.I., Diack, I., Drewitt, A.L., Grice, P.V. & Gregory, R.D. 2014. Synergies between site protection and agri-environment schemes for the conservation of waders on lowland wet grasslands Ibis 156: 576-590. 

Reducing predation risks

A reduction in predation can be effected by direct control of species such as corvids, mustelids and foxes but other tools are also available:

Carrion crow Andy Hay rspb-images

Andy Hay/RSPB images

Removing isolated trees, telegraph posts and wires that are used as look-out perches by corvids:  Berg, A., Lindberg, T. & Kallebrink, K.G. 1992. Hatching success of Lapwings on farmland – Differences between habitats and colonies of different sizes. J. Anim. Ecol. 61: 469-476 and MacDonald, M.A. & Bolton, M. 2008. Predation on wader nests in Europe. Ibis 150: 54-73.

Using electric fences to keep out foxes and badgers. Malpas, L. R., Kennerley, R. J., Hirons, G. J., Sheldon, R. D., Ausden, M., Gilbert, J. C. & Smart, J. 2013. The use of predator-exclusion fencing as a management tool improves the breeding success of waders on lowland wet grassland. Journal for Nature Conservation: 21, 37-47.

Designing the lay-out of water features so as to reduce fox/nest interactions: Bellebaum, J. & C. Bock. 2009. Influence of ground predators and water levels on Lapwing Vanellus vanellus breeding success in two continental wetlands. Journal of Ornithology 150: 221–230.

Diversionary feeding – providing areas of long grass which act as refuges for small mammals: see other WaderTales Blog.

Decisions for the future

Lapwing nest Andy Hay rspb-images

Andy Hay/RSPB images

The majority of the chicks monitored in this study were predated before fledging.  If this mortality can be reduced then sites which are managed with wader chicks in mind have the potential to support population recovery.  Decisions upon how to reduce predation will need to be based upon the effectiveness and costs of the suite of solutions that are available, as well as ethical decisions as to which predators can be controlled and when – a potentially tricky issue for those managing nature reserves.

Mason, L.R. and Smart, J. Wader chick condition is not limited by resource availability on wader-friendly lowland wet grassland sites in the UK. Wader Study 122:3 Dec 2015


 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

 

NEWS and Oystercatchers

It’s amazing what you can find when walking along a beach with a pair of binoculars

Curlew in snow

Curlews waiting for the tide to drop: Graham Catley

Thousands of British and Irish birdwatchers visit estuaries but there’s a lot of coastal habitat that gets little attention.  That’s where you’ll find 87% of the UK’s Purple Sandpipers, over half of the Turnstones and nearly half of the Ringed Plover – or those were the figures nine years ago.  It’s time to update these estimates, which is where NEWS-III came in. That’s the catchy name for the third Non-estuarine Waterbird Survey, which operated in the UK and Ireland over the period 1 Dec 2015 to 29 Feb 2016.

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We’ll be looking out for colour-ringed Oystercatchers: Tómas Gunnarsson

We covered 6 beach sections as our contribution to NEWS-II over the Christmas period 2006/07: three horrible stretches right next to the main A78 along the Clyde coast and three lovely beaches on the island of Cumbrae. We found 57 waders on the first set, while dodging the traffic, and 184 on a very relaxed day trip from Largs by ferry. There were comparable numbers of Curlew, Turnstone and Redshank but more Oystercatchers on the wider, island beaches.  That’s where we also found our only Ringed Plover, as well as 11 Purple Sandpipers and 3 Lapwing.

cumbrae comparisonThis year, we found far fewer waders than nine years ago. The table alongside provides a comparison for the three sections that we covered on Cumbrae for NEWS II and NEWS III. We failed to find any Purple Sandpipers in any of the 17 sections of the Clyde coast that we covered but were surprised to see a total of 5 Greenshanks. There seemed to be far fewer seabirds too. This is just a tiny snap-shot that may not be representative of the picture across the whole of the coastline of Britain & Ireland. Let’s hope that, despite the stormy weather, there was sufficient coverage for robust anlayses to be carried out by BTO staff.

RP WeBSWe know that wader number on estuaries are changing.  For instance, in the last few years, numbers of Ringed Plover in the UK have been falling (see figure).  The declining line indicates a significant drop but it won’t be quite such a concern if this year’s NEWS-III surveyors find that there are now more Ringed Plovers on open coasts.  That may seem like an optimistic suggestion, unless you look at changes between NEWS (1997/98) and NEWS-II (2006/07).  During this period, at the same time that WeBS counts of estuaries were falling, there was actually a 25% increase in Ringed Plover numbers on open coast.  Perhaps this redistribution from estuaries to open coasts has continued?

NEWS tableTwenty-one species of wader were recorded during NEWS-II, with Oystercatcher being the most numerous with an estimated total of 64,064 for the whole non-estuarine coastline of the UK. The full report is available on the BTO website .  With support from hundreds of volunteer birdwatchers it was possible to make population estimates for the 12 most numerous species, including the non-estuarine specialists, Ringed Plover, Sanderling, Purple Sandpiper and Turnstone.  These four species accounted for estimates of 15,230, 6,295, 11,306 and 30,122 individuals respectively.  The table alongside shows the intertidal-zone totals and the percentage of the total UK population that each estimate comprises, based on Population estimates of birds in Great Britain & the United Kingdom by Musgrove et al which was published in British Birds.

Five of the species that were in the top 12 for NEWS-II have been categorised as near-threatened by IUCN/BirdLife.  Oystercatcher is the most numerous of the five, with over 64,000 in intertidal areas of the open coast, representing nearly 20% of the national wintering population.  There are relatively small numbers of Bar-tailed Godwit, Lapwing and Knot but 26,744 Curlew is equivalent to 17.8% of the UK total.   There’s a WaderTales blog about the near-threatened designation of Curlew.

Turnstone Belsey

59% of the UK’s Turnstone ar found on the open shore: Derek Belsey/BTO

Unfortunately for the scientists who organised NEWS-III there is a huge disparity between the distribution of birdwatchers and the number of coastal stretches that would ideally be surveyed, so let’s hope a good number of English birdwatchers decided to spend a few days in Scotland over the survey period.  Three-quarters of the open coast in the UK is in Scotland (all those crinkly bits, sea-lochs and islands) with Northern Ireland, England and Wales respectively having approximately 2.3%, 16.0% and 6.6%.  Taking account of the spread of the available sites, there’s a relatively uniform UK-wide distribution of most species, although  Sanderling has a southerly bias to its distribution and Purple Sandpiper a strong northern bias.

NEWS-III was not just about waders; volunteers were asked to record other waterbirds too. Our counts for NEWS-II covered Cormorant and Shag, Mute Swan, Eider, Red-breasted Merganser, Wigeon, Mallard, Guillemot and Grey Heron.

oyc table

Data from BTO ringing report

Whilst I was delighted to use WaderTales to promote NEWS-III, there was an ulterior motive. We wanted counters to look out for Oystercatchers wearing colour rings. Icelandic Oystercatchers can be encountered almost anywhere but the ones in England are very much outnumbered by those from Norway, the other main source of wintering birds. The table alongside gives an idea of the north-westerly distribution of birds with an Icelandic origin.

oycmap.pngColour-ringed Icelandic Oystercatchers are part of a new project to look at how climate change might be affecting migration patterns. There’s a blog about the project here. The map alongside shows where colour-ringed birds from the study areas in Iceland have already been found, with most in Scotland and Ireland.  Birds will either be wearing 3 colour-rings and a green or white flag or two colour-rings and an engraved darvik.

NEWS only happens every few years so this was a great opportunity to contribute to our understanding of the conservation status of some important species, several of which are now near-threatened. I am looking forward to the results with interest, and a little concern.


 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

Why is spring migration getting earlier?

In Iceland, young trend-setting Black-tailed Godwits are changing the timing of spring migration

Flocks of up to 5000 Black-tailed Godwits gather in Alftafjordur in spring: Tómas Gunnarsson

Flocks of up to 5000 Black-tailed Godwits arrive in Alftafjordur (East Iceland) in spring: Tómas Gunnarsson

In recent years, earlier arrival of spring migrants has been widely reported in birds as diverse as swallows and waders but it’s not a universal trend; species such as British Cuckoos and Icelandic Whimbrels have not changed their arrival dates.  Interestingly, many of the species that have not advanced timing tend to be those that are declining.  By thinking about the mechanisms that enable some species to take advantage of earlier spring warming it might be possible to explain how timings and population changes may be linked.

Are individual Black-tailed Godwits arriving earlier each spring? (Photo: Nigel Clark)

Are individual Black-tailed Godwits arriving earlier each spring? (Photo: Nigel Clark)

The simplest way for spring migration to advance would be for individual birds to change their arrival dates, arriving earlier now (either because they have departed earlier or migrated faster) than they did in previous years.  These changes could be facilitated by changes to weather conditions before, during or after migration.  In general, the arrival of short-distance migrant species has advanced more than long-distance species, which has led to suggestions that individual birds are able to assess conditions on their breeding grounds from afar, and to ‘fine-tune’ arrival accordingly. This could explain why long-distance migrants seem less well able to change their schedules than species which have less far to travel.

Figure 1: Changes in first spring arrival dates of six species of waders in southern Iceland from 1988 to 2009 (reproduced from Gunnarsson & Tómasson 2011)

Figure 1: Changes in first spring arrival dates of six species of waders in southern Iceland from 1988 to 2009 (reproduced from Gunnarsson & Tómasson 2011)

This pattern of advances in arrival dates, and greater advances in short-distance migrants is seen in birds arriving into Iceland each spring (Gunnarsson & Tómasson).   By monitoring the first dates of a range of migratory breeding species to the area around Laugarás, an inland village in southern Iceland, over the period 1988 to 2009, Tómas Gunnarson and Gunnar Tómasson showed that species which spend the winter further south than France showed no change in arrival, whilst those from further north in Europe were returning earlier.  The southern group included the only wader in the Gunnarsson & Tómasson study which uses this migration strategy, Whimbrel (see diagram).

GL-YX on a windy day in western Iceland. He has been seen in eleven years. Despite the vagaries of spring weather, his arrival dates have only been spread over nine days (standard deviation 3.5 days) and have not advanced over the period 2003-2015

GL-YX on a windy day in western Iceland. He has been seen in eleven years. Despite the vagaries of spring weather, his arrival dates have only been spread over nine days (standard deviation 3.5 days) and have not advanced over the period 2003-2015

One of the species that has advanced spring arrival (by about two weeks in the last two decades) is the Black-tailed godwit.  Since 2000, we have been recording arrival dates of individually colour-ringed godwits into coastal Iceland – giving us the opportunity to assess whether individuals have indeed brought forward their time of arrival.  By making regular visits to the same sites we have discovered that the dates when we first come across individuals are remarkably consistent.  Although the arrival of the whole population is spread over a five or six week period, the window in which a specific Black-tailed Godwit appears is generally predictable, whether he or she is a bird that we tend to first see in mid-April or mid-May.  There are annual differences, of course, which appear to be linked to periods of adverse weather during the period of the sea-crossing (Gunnarsson et al 2006), from departure points in The Netherlands, The UK Ireland, France and Portugal, but there is no significant trend.

Dates of spring arrival into Iceland of 54 individually marked black-tailed godwits recorded on arrival in between 4 and 8 years, from 1999 to 2012 (reproduced from Gill et al. 2014). Whether an individual arrives early (left-hand birds) or late (right), the sighting dates for each bird are highly consistent.

Dates of spring arrival into Iceland of 54 individually marked black-tailed godwits recorded on arrival in between 4 and 8 years, from 1999 to 2012 (reproduced from Gill et al. 2014). Whether an individual arrives early (left-hand birds) or late (right), the sighting dates for each bird are highly consistent.

timing pop v indivAlthough the arrival date for the population has been advancing at ~0.8 days per year (Gunnarsson & Tómasson 2011), there has been no trend in individual arrival dates (not significantly different to zero days per year); Gill et al. 2014.

Most of the godwit chicks were ringed by groups of volunteers led by Pete Potts and Ruth Croger (Photo: Tómas Gunnarsson)

Most of the Black-tailed Godwit chicks were ringed by groups of volunteers led by Pete Potts and Ruth Croger (Photo: Tómas Gunnarsson)

If individuals are consistent in arrival but the population is advancing, the advance must presumably result from new birds recruiting into the population being earlier-arrivers than recruits from previous years?  Fortunately, there is a second long-running set of data that’s available to answer this question, in a large part because of the efforts of Pete Potts and Ruth Croger of Farlington Ringing Group.  In the period 1999 to 2014, they organised teams of volunteers to ring Black-tailed Godwit chicks in Iceland, with the support of the Icelandic Natural History Museum.  Significant contributions to the total of over 350 colour-ringed chicks were also made by Tómas Gunnarsson and José Alves, while researching the breeding ecology of Black-tailed Godwits for the Universities of East Anglia and Iceland.

Dates of spring arrival into Iceland of 46 individuals hatched in different years and subsequently recorded on spring arrival (reproduced from Gill et al. 2014)

Dates of spring arrival into Iceland of 46 individuals hatched in different years and subsequently recorded on spring arrival (reproduced from Gill et al. 2014)

Wader chick mortality is quite high and there are further losses in the eighteen-month period between autumn departure from Iceland and the first return trip, eighteen months later, so it was wonderful to have a sufficiently big cohort of marked recruits to look at patterns and trends.  For this study, arrival dates for 46 individuals of known hatch year were available for analysis.  As can be seen from the graph, arrival dates of new recruits have been getting earlier, with birds hatched in the last decade arrive around two weeks earlier than individuals hatched in the 1990s.

There are several reasons why recent recruits may be arriving earlier than in previous years, but the most likely is that this is a knock-on effect of advances in godwit laying dates that have occurred in recent decades.  Icelandic godwits nest earlier in warmer springs, and the frequency of warmer springs has increased.  Early fledging may benefit new recruits, by increasing the time available for them to migrate south, locate a good winter site and be in condition to return early when they recruit into the breeding population (Alves et al. 2013 http://www.esajournals.org/doi/abs/10.1890/12-0737.1  http://dx.doi.org/10.1890/12-0737.1). As their arrival date will be consistent thereafter, the overall timing of arrival of the population will advance.

Will this young Black-tailed Godwit contribute to our understanding of the timing of migration? (Photo: Tómas Gunnarsson)

Will this young Black-tailed Godwit contribute to our understanding of the changing timing of migration? (Photo: Tómas Gunnarsson)

Many other studies of different species in which individuals are tracked during migration are showing similar levels of consistency in individual timing of migration.  What then is causing the variation among species in rates of advance?  Long-distance migrants typically arrive later on the breeding grounds and breed quite soon after arrival, while short-distance migrants can have quite large time gaps between arrival and laying, depending on conditions for breeding. Short-distance migrants therefore have more capacity to advance laying dates (because they are on the breeding grounds waiting for suitable conditions), while long-distance migrants, such as Whimbrels in Iceland, arrive later and so cannot breed earlier even in a warmer year. Advances in spring arrival dates may therefore result from advances in laying dates and associated benefits of early fledging for recruits, and lack of advance in long-distance migrants may be a consequence of arriving late and hence being unable to take advantage of early, warm spring conditions.

In the Icelandic subspecies of Black-tailed Godwit, which is expanding in both number and distribution, it is clear that young recruits to the breeding population are driving the advance in timing of migration.  We only know this because of the long-term programme of chick ringing by volunteers and because we have been able to record the timing of individual birds’ migratory activities over a large number of years.  Funding for this work has been provided by the volunteers themselves, NERC , Icelandic Research Council  and EU TMR.

This blog is based upon research presented in the following open access paper:

Gill, J.A., Alves, J.A., Sutherland, W.J., Appleton, G.F., Potts, P.M. & Gunnarsson, T.G. 2013 Why is timing of bird migration advancing when individuals are not? Proceedings of the Royal Society B. , 281, 20132161


 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

Is the Curlew really ‘near-threatened’?

If a Curlew can live for over 32 years and there are flocks of 1000 in Norfolk, how can they be described as near-threatened? 

Dark times lie ahead for Curlew? (© Graham Catley)

Dark times lie ahead for Curlew? (© Graham Catley)

Thirty years ago there were eight members of the world-wide curlew family but now we may well be down to six.  The planet has lost one species, the Eskimo Curlew, with no verified sightings since the 1980s, and probably the Slender-billed Curlew as well.  Of the others, Far Eastern Curlew and Bristle-thighed Curlew are deemed to be endangered and vulnerable, respectively, and our own Curlews are classed as near-threatened, which is the next level of concern. This may seem strange, especially when flocks of 1000 can be seen on the Norfolk coast.  However, evidence suggests that we should take heed of what is happening to other members of the curlew family, as we consider the future of this evocative species with its wonderful bubbling curl-ew calls.

Threat levels for the eight members of the Curlew family (based on IUCN BirdLife assessments)

Threat levels for the eight members of the Curlew family (based on IUCN/BirdLife assessments)

Our Curlew – more properly called the Eurasian Curlew – was until relatively recently a locally popular game species in Britain, especially in September and October, when birds are reputed to be particularly flavoursome.  A male Curlew is equivalent in weight to a Wigeon (or two Teal) and the bigger female may well be as heavy as a Mallard, so it is not surprising that they were worth targeting.  They came off the British quarry list in 1981.

Map showing movements of ringed curlews. Purple dots indicate where British/Irish ringed birds have been recovered and orange dots show ringing sites of birds found here and wearing foreign rings. Maps of movements can be found on the BTO website at http://www.bto.org/volunteer-surveys/ringing/publications/online-ringing-reports

Purple dots indicate where British/Irish ringed Curlews have been recovered and orange dots show ringing sites of birds found here and wearing foreign rings. Maps of movements can be found at http://www.bto.org/volunteer-surveys/ringing/publications/online-ringing-reports

The Curlews that we see on the Norfolk coast in autumn and winter are drawn from a wide breeding area; some are of British origin but many are from Scandinavia, Finland and Russia.  The Wash Wader Ringing Group recently received a report of a bird that was ringed in Norfolk in September 2000 and recovered in Izhma in Russia in May 2014.  At 3300 km (2000 miles) this is nearly as far away as the furthest east dot on the map of Curlew recoveries, shown here and published on the website of the British Trust for Ornithology.  The bird was an adult when ringed so must have been at least 15 years old when shot.  This seems like a good age for a Curlew but is less than half of the British longevity record, set by a chick ringed in Lancashire in 1978 and found dead on the Wirral in 2011.

Curlew mortality is higher in severe winters (© Graham Catley)

Curlew mortality is higher in severe winters (© Graham Catley)

Curlew numbers on the Wash, which sits between the counties of Norfolk and Lincolnshire, increased dramatically when shooting ceased in 1981, although milder winters could have also have been influential.  In the five years immediately before the ban, the average maximum, winter Wetland Bird Survey count on the Wash was 3281, rising to 9642 in the period 2006/07 to 2010/11.  There were similar increases on the North Norfolk coast and a bit further south at Breydon Water.  The broader, national picture is one of increase between 1981 and 2001, although generally at a lower level to that seen in Norfolk, followed by a steady, shallow decline.  If numbers are higher than they once were does this mean that we should be less concerned about Curlews – and what is the justification of the species’ near-threatened designation?

Curlews fly vast distances to spend the winter on the estuaries of Britain & Ireland (© Graham Catley)

Curlews fly vast distances to spend the winter on the estuaries of Britain & Ireland (© Graham Catley)

Conserving migratory species is difficult because individuals rely on different resources in different countries at different stages of the year.  For Curlews, there is evidence that breeding season problems are at the heart of large decreases in numbers in Russia, through the Baltic and into The Netherlands – the countries from which much of the wintering population on the east coast is drawn.  According to the European Commission’s species management plan, drivers of decline include wide-scale intensification of grassland management for milk production, land-abandonment and increased predation in some areas.  Autumn, winter and spring hunting is thought to have had a lesser but contributory effect to the long-term losses, with hunters across the European Community shooting between 3% and 4% of the population each year.  In the last twenty years, within the EC, hunting of Curlew has been confined to Ireland, Northern Ireland and France.  Much of this shooting pressure was and is in France, where coastal hunting of Curlew has been reinstated after a five year moratorium.

curlew webpageFocusing on Britain and Ireland, we have seen major losses in our breeding populations.  In Ireland, the Curlew population is estimated to have dropped from 5000 to 200 pairs in the twenty years between 1991 and 2011, and there has been an 80% decline in Wales.  There’s more about these distributional changes in a 2012 article written for the BTO website.

Curlew productivity in several areas appears to be very low and it is possible that the adults we are seeing are part of an ageing population.  As has been shown in seabirds, counts of adults can give a false sense of security, as it is easy not to notice that there is little recruitment of new, breeding adults into the population, with obvious long-term consequences.

Graph shows the changing Curlew population in Great Britain (Wetland Bird Survey)

Graph shows the changing Curlew population in Great Britain (Wetland Bird Survey)

The decline in the number of breeding Curlew in Great Britain is clearly reflected in monthly, winter counts undertaken by volunteers on west coast estuaries.  On the Dee, for instance, the average peak-winter count dropped from 6109 in the early 1970s to 4348 in the five years after the shooting ban, rose to 5081 in the late 1990s but then slipped back to 3802.

With relatively few continental birds, the Wetland Bird Survey trend reflects more local declines

With relatively few continental birds, the Wetland Bird Survey trend reflects more local declines

In Ireland and Northern Ireland, a total ban on shooting Curlew was announced in 2012, brought in once it was clear that the estimated November harvest of between 6% and 8% was unsustainable and set against a background of the collapse of the local breeding populations.  The same local reasoning lies behind continuing protection in Wales, western England and in much of Scotland, especially at a time when financial support to land-managers is being used to try to bolster British breeding numbers.  In eastern England, Curlew conservation has a more international flavour, as we provide a safe haven for birds from as far away as Russia.

Britain & Ireland, between them, provide winter homes for half of the Europe-wide population of Curlews (about 210,000 out of 420,000), with the Netherlands holding 140,000 birds.  There are also significant flocks in Germany and about 20,000 in France.  These may seem like reasonable numbers but, given that fewer chicks are being raised, the number of adults is declining, two close relatives have been driven to extinction and other curlew species are in trouble, the label of near-threatened seems highly appropriate.

We should be proud of our wintering Curlews in Great Britain, where numbers have stabilised, albeit at a level that is 20% lower than at the turn of the century, but there is no room for complacency in Northern Ireland, where the decline continues.

Addendum: Curlew was added to the red list of the UK’s Birds of Conservation Concern on 3 December 2015

On autumn high tides, flocks of Curlew roost on east coast stubble fields (© Graham Catley)

On an autumn high tide, a flock of Curlew roosts on an east coast stubble field (© Graham Catley)


 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