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 was reinstated after a five year moratorium. Read blog about this here.

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 (with further declines since – see Ireland’s Curlew Crisis blog below). There has been an 80% decline in Wales and other losses elsewhere.  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.

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.

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

With relatively few continental birds in Northern Ireland, the Wetland Bird Survey trends probably reflect local declines

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.

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

Other WaderTales blogs about Curlew

  • Why are we losing our large waders? takes a look at a review of the common threats faced by the 13 Numeniini species (godwits, curlews and Upland Sandpiper).
  • Curlews can’t wait for a treatment plan focuses on the primary drivers of the species’ breeding decline in Great Britain.
  • Sheep numbers and Welsh Curlew looks at habitat associations within a large site  in the Welsh uplands; getting the grazing regime right seems to be very important.
  • Curlew Moon has at its heart a review of Mary Colwell’s book of the same name but also summarises some of the issues being faced by Curlew in Ireland and the UK.
  • Ireland’s Curlew Crisis focuses on the nationwide breeding survey between 2015 and 2017, which revealed a 96% decline in the number of pairs in just 30 years.
  • Curlews and foxes in East Anglia suggest that ‘curlew plots’ may be helpful in the fight to conserve the species.
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

A helping hand for Lapwings

This article has been slightly adapted from one written for the Autumn 2015 edition of The Harrier, published by the Suffolk Ornithologists’ Group

Lapwing in flight: Richard Chandler

Lapwing in flight: Richard Chandler

The space-invader cries of displaying Lapwings are welcome signs of spring across much of Britain’s countryside and losses of this iconic species, especially in lowland England, have been well chronicled.  Conservation organisations, and the RSPB in particular, are successfully supporting breeding numbers on nature reserves but how can their interventions be replicated on working farms, without flooding fields and installing fox-proof electric fences?

On the look-out: Grahame Madge/RSPB impages

On the look-out: Grahame Madge/RSPB impages

Dr Jen Smart of the RSPB Centre for Conservation Science and Professor Jenny  Gill of the University of East Anglia have been studying breeding waders on  RSPB Reserves in the Norfolk Broads for over ten years, but more recently they have extended their wader research into commercially managed grasslands across Norfolk and Suffolk, using funding from Defra.  At the February 2015 ‘Foxycology’ conference, Dr Smart explained how the RSPB is trying to manage the conflict between the conservation of ground-nesting birds and foxes.  The RSPB does not rule out shooting as a protection measure – there’s active fox control in the study site – but prefers to adopt non-lethal solutions to the predation problem.  One answer may be to provide foxes with ‘convenience food’, in the form of mice and voles.  If it’s easier to find mice and voles than wader nests and chicks then perhaps that’s what foxes will do?

Predation is a natural process but rates can be severely skewed by the way that the countryside is managed, especially when the balance of predator and prey is disturbed.  Many predators are opportunists, with species such as foxes, crows, gulls and raptors switching their activities to take advantage of local food availability.  Seasonal abundance of food resources can affect both survival and productivity.  An inexperienced young fox must have a better chance of surviving the winter if he is presented with a generous supply of released pheasants, whilst a vixen, trying to raise a litter of cubs, will find easy pickings in a gull colony.  In the same way, a nature reserve that is full of nesting waders will often attract foxes during the breeding season.

By creating shallow ditches, which add water and insects to grassland habitats, Lapwing productivity is increased: Mike Page/RSPB

By creating shallow ditches, which add water and insects to grassland habitats, Lapwing productivity is increased: Mike Page/RSPB

The RSPB has become very good at increasing populations of wading birds breeding on their lowland nature reserves but staff are frequently frustrated by the low numbers of young birds that survive through to fledging in some years.  Adding water to the landscape, in the form of pools and ditches, attracts high densities of breeding waders, as these wet features provide insect-rich places to which adults can take their chicks.  The RSPB/UEA research team has found that Lapwing nests are far more successful when birds nest at high densities, presumably because they work together to look out for and drive off potential predators, and they also found that Redshanks benefit from the activities of the more numerous and defensive Lapwings.  Practical actions, such as clearing woodland that abuts wetland or removing single trees in which crows sit to spot the next meal, have been shown to reduce avian predation in the daytime, to such an extent, in fact, that three-quarters of nest-losses are now taking place at night.

Lapwing chick: Richard Chandler

A young and vulnerable Lapwing chick: Richard Chandler

Using cameras, the team has shown that 70% of the culprits filmed taking eggs are foxes, with badgers coming a distant second, at 12%.  Wader chicks leave the nest soon after hatching, and RSPB research has shown that chick predation is then largely from foxes at night and raptors in the daytime, but with stoats, weasels and opportunistic birds, such as grey herons, taking smaller numbers.  Overall, by far the biggest threat to productivity is the fox.

One fox (and badger) deterrent that is available on nature reserves is to use well-maintained mains-supplied electric fences to surround fields in which waders nest.  Trials by the RSPB have shown that Lapwing fledging success is significantly improved in fenced areas, increasing from just over 0.2 chicks per pair to 0.8 chicks.  The target level for a sustainable population is 0.6 young per pair so the lower figure is well below par and 0.8 should be providing a surplus of birds that can go on to nest elsewhere.  Fences are not perfect, however; they do not exclude predators such as stoats and weasels, and the increased success of nests means high densities of chicks can be an irresistible resource for opportunistic and adaptable aerial predators trying to feed their own young.  Fencing is also only really effective on a relatively small scale so does not provide the solution to what is a landscape-scale problem.  RSPB research has shown that there is a lot of variability in predation rates, which provides opportunities to try to understand the complex interactions between foxes, mustelids (stoats and weasels), small mammals and waders.

In open grassland, Lapwings can keep an eye out for approaching predators: Richard Chandler

In open grassland, Lapwings can keep an eye out for approaching predators: Richard Chandler

Much of the patchiness of productivity within a site is linked to the amount of grass in fields and along field edges.  Grazing is a key management tool in wet grasslands, with cattle creating the short and varied sward structure that is attractive to a range of breeding waders.  By using ink tracking tunnels, within which mammals leave their footprints, and looking for field-signs of activity, Dr Becky Laidlaw has been able to show that this short grass is of little use to mice and voles.  She discovered that they prefer verge areas, outside the fields, where the grass is at least 20 cm tall and where there is ground-level vegetation cover of more than 80%.  Using data on wader nest success collected over 10 years, she was also able to show that Lapwings nesting in fields close to this small mammal habitat had lower rates of predation. Adding in tall grass strips and patches within a farmland landscape could potentially increase the populations of small mammals, thereby distracting foxes and mustelids, and reducing predation pressure.  Avian predators of wader chicks might appreciate this intervention too!  This work is published as:

The influence of landscape features on nest predation rates of grassland-breeding waders by Rebecca A Laidlaw, Jennifer Smart, Mark A Smart & Jennifer A Gill in Ibis 157:4 Oct 2015

Over the last two years, the RSPB/UEA team has worked with landowners of commercial grasslands across East Anglia, who between them are responsible for a large percentage of remaining breeding wader populations. Building on the work on reserves, the aim was to understand whether habitat suitability and predation processes differ between reserve and wider countryside waders.  To accomplish this, they assessed the extent to which grassland management options within agri-environment schemes support small mammal populations, as well as measuring field wetness, Lapwing densities and nest predation rates.  They also assessed the importance of different nest predators for waders nesting in the wider countryside and within nature reserves.

A weasel leaves its mark: Becky Laidlaw

A weasel leaves its mark: Becky Laidlaw

Becky and her team found similar distributions of small mammals in the wider countryside as had already been found on nature reserves.  Within both, there were higher densities of small mammals within grassland habitats outside of fields, while presence within fields did not vary significantly among fields managed under different grassland agri-environment options.  Encouragingly, densities of Lapwing nesting in fields managed in accordance with the breeding wader option were significantly higher than in fields with no interventions. Lapwings nesting in areas with many other Lapwings and nests that were closer to patches of small mammal habitat were less likely to be predated, but the rate of Lapwing nest predation did not differ between the wider countryside and reserves.  It should be possible, therefore, to create Lapwing hot-spots outside of nature reserves, thereby expanding the reproductive potential of East Anglia.  Unsurprisingly, given the previous findings about the causes of nest-losses on nature reserves, wider-countryside sites where foxes were present experienced both higher overall nest predation and nocturnal nest predation.

Redshank also benefit for management designed to support Lapwings and probably appreciate the shared look-out duties Photo: Richard Chandler

Redshank also benefit for management designed to support Lapwings and probably appreciate the shared look-out duties Photo: Richard Chandler

The main findings of this study are that wader nest predation rates and spatial patterns of nest predation on lowland wet grasslands are remarkably similar inside and outside reserves. This should help to directly inform the design and development of lowland wet grassland landscapes, making them capable of attracting and supporting sustainable populations of breeding waders within the constraints of commercial grasslands.  Jen Smart is optimistic; “If we can provide wet fields that look attractive to Lapwings in spring and patches of tall vegetation that hold high numbers of small mammals it ought to be possible to improve nesting success and productivity”.  She and her colleagues are now looking at how a range of different agri-environment options might be used to create such landscapes.  The next phase of the project will be to try out the most promising options, in order to see the scale at which these patches of tall vegetation for small mammals need to be provided if they are to deliver the desired result – more breeding waders.

Update 

The are several other WaderTales blogs that may be of interest to people who like Lapwings:

For a full list of WaderTales blogs visit https://wadertales.wordpress.com/about/

 


 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 do some Black-tailed Godwits wear colour-rings?

The birdwatchers at Cley provide daily observations of the colour-ringed Black-tailed Godwits that turn up on the site, revealing some fascinating stories and contributing massively to migration research.

This blog was originally written for the Norfolk Wildlife Trust’s magazine, Tern.

Flock of Black-tailed Godwits at Cley: Pat Wileman

Flock of Black-tailed Godwits at Cley: Pat Wileman

No two visits to Cley are the same; the birds change with the seasons and even from day to day.  If there are 200 Black-tailed Godwits in front of Daukes hide on Tuesday and only 100 on Thursday does that mean that half have moved on – or did all of the earlier birds leave, to be replaced by a new selection?  The fact that several individuals wear colour-rings enables regular godwit observers, such as David and Pat Wileman and Mark Golley, to help provide some answers.

The highest Cley counts of Black-tailed Godwits now occur in the autumn, when birds can be found feeding or roosting on the scrapes and lagoons, pulling worms from the wet meadows or picking up grain from nearby stubble feeds.  Many colour-ringed birds have only been seen once but others become old favourites, like ‘orange/green – orange/green-flag’.  Until 2015 he spent the late summer weeks at Cley moulting out of his red summer plumage (see series of three pictures below).  As autumn turned to winter, he flew onwards to the Tagus Estuary in Portugal, where he was first ringed in 2007 by José Alves, one of a team investigating migration at the Universities of East Anglia, Iceland and Aveiro (Portugal).

Three pictures of the same bird, moulting out of its breeding plumage. Photographs by Chris Cook, Pat Wileman & Richard Chandler

Three pictures of the same bird, moulting out of its breeding finery and into winter plumage. Photographs by Chris Cook, Pat Wileman & Richard Chandler

Another well-watched bird is ‘lime – yellow/black//white’.  She was first caught on the Wash in September 2002 and has spent every March/April at Cley or Stiffkey. She has been seen in Ireland in mid-winter and nests in northern Iceland.  This bird was already an adult when ringed 12 years ago so her exact age is unknown.  The current record for Icelandic Black-tailed Godwits is 25 years but colour-ringing is likely to show that they can live even longer.

The ring on the lower part of the right leg used to be white! This distinctive staining is an extra complication for observers at Cley. Photo: Chris Cook

The ring on the lower part of the right leg used to be white. This distinctive staining is an extra complication for colour-ring observers at Cley. Photo: Chris Cook

Cley is just one observation point across the whole of the Icelandic Black-tailed Godwit’s range.  Jenny Gill, who leads the godwit research at UEA, is working with colleagues in Iceland, Portugal, France, Spain, Ireland and across the UK to understand migration patterns and their consequences for survival and breeding success.  Every reported set of colour-rings is important, even if the same bird was seen in the same spot yesterday.  It may not be there tomorrow, in which case today’s record has helped to pinpoint the departure date.  Visitors at Cley can send their sightings to David at cbcrecords@talktalk.com , write them in the hide log book or contact Jenny at j.gill@uea.ac.uk

Whilst the vast majority of Cley Black-tailed Godwits are of the Icelandic race, a few birds from the small population of birds that breed in the Ouse and Nene Washes also pass through in the autumn. Later they will join thousands of birds from continental Europe, wintering in Iberia and west Africa.  The Icelandic colour-ringed birds are providing fascinating insights into the migratory movements of that subspecies, the numbers of which have risen at the same time as the numbers of the continental subspecies have declined.  Icelandic birds winter all around western Europe; Cley birds have been seen in France, Portugal, Spain and Ireland, as well as around much of the UK.

Colour-ring sightings have helped to reveal a huge amount about Black-tailed Godwits.  Amongst many other findings:

Rates of population increase were greater on estuaries with low initial numbers, and Black-tailed Godwits on these sites had lower prey-intake rates, lower survival rates and arrived later in Iceland than those on sites with stable populations. The Buffer effect and large-scale population regulation in migratory birds. JA Gill, K Norris, TG Gunnarsson, PW Atkinson & WJ Sutherland. Nature 412, 436-438 (26 July 2001).

We know that birds from the same pair have nothing to do with each other outside the breeding season, even wintering in different countries, but that they need to arrive on territory within a day or two of each other if there is not to be a divorce.  Pair Bonds: Arrival synchrony in migratory shorebirds. TG Gunnarsson, JA Gill, T Sigurbjörnsson & WJ Sutherland.  Nature 431, 646 (7 October 2004). There’s a WaderTales blog about this paper.

We have learnt that spring migration is getting earlier, driven by new recruits getting back to Iceland earlier than older birds.  Why is timing of migration advancing when individuals are not? , , , , ,

Want to know more?

This blog tells more stories about individual Black-tailed Godwits and the birdwatchers who study them: Godwits and Godwiteers.

There are many more WaderTales blogs about Black-tailed Godwits. Click here to see what is available. 

Cley is a great place to see godwits at really close quarters, as are a number of other nature reserves around the country.  Reports of colour-ringed birds provide an important element of ongoing migration research.  Please contact Jenny Gill at j.gill@uea.ac.uk and you will receive a life-history of your bird, either from Jenny or from one of her collaborators.


 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