January to June 2019

blog CU postOne 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.

Click on a link in bold to read an individual blog.

You can sign up to receive an e-mail notification when a new blog is published.


GFA in IcelandGraham (@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.

Not-so-Common Sandpipers

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

blog horiz water

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

Common or Spotted?

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

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

Population changes

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

Breeding season

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

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

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

The southward migration

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

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

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

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

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

blog flock

Life in the south

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

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

The northward migration

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

Why so few Common Sandpipers?

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

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

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

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

Common & Spotted Sandpipers

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

Book Details

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

New research

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

t.mondain-monval@lancaster.ac.uk


GFA in Iceland

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

@grahamfappleton

Scottish Wader Woes

The report on Scotland’s terrestrial bird species, covering the period 1994-2016, did not make easy reading for wader lovers. All but one species was contributing negatively to the upland bird indicator, with declines of over 40% for breeding Lapwing, Curlew, Dotterel, Oystercatcher and Golden Plover. In this short blog, there are links to information that helps to explain what might be going wrong for Scotland’s waders.

The figures from the report have been update in the Breeding Bird Survey for 2018 (published 2019) and these figures are now included below. Golden Plover is no longer part of the ‘over 40%’ club.

The full report is available on the SNH website (https://www.nature.scot/information-library-data-and-research/official-statistics/official-statistics-terrestrial-breeding-birds)

The updated Breeding Bird Survey results are available on the BTO website (https://www.bto.org/our-science/projects/bbs/latest-results)

One species has been increasing – Snipe up 22% *

snipe abundance change* BBS results for Snipe for 1995-2017 revise the change figure to show an increase of 32%.

The one spot of good news is that breeding Snipe numbers in Scotland have risen over the period 1994 to 2016. This is particularly encouraging, given declines in much of the rest of Britain and Ireland, as you can see in the map alongside and read in this WaderTales blog Snipe and Jack Snipe in the UK and Ireland.

In the map, produced for Bird Atlas 2007-11 (BTO, BirdWatch Ireland & SOC), pink colours show abundance increases and grey areas show decreases.

Lapwing declines largest – down 63% *

GHH picture* BBS results for Lapwing for 1995-2017 revise the change figure to show a decrease of 55%.

When a widespread species such as Lapwing is in decline this is bad news. Subtle difference in the way that lowland valleys are farmed may be part of the problem, as illustrated in this WaderTales blog, based on work by Mike Bell, written up with the help of John Calladine, of BTO Scotland: 25 years of wader declines.

Curlew down 62% *

Blog Jill P* BBS results for Curlew for 1995-2017 revise the change figure to show a decrease of 61%.

The Curlew is causing huge concerns in Ireland and Wales, where conservationists are contemplating its disappearance as a breeding species. Scotland holds much larger numbers but a decline of nearly two-thirds suggests that there are major problems here as well.

Two WaderTales blogs tell the Curlew story. Is the Curlew really near-threatened explains why we should be so worried about what is happening and Curlews can’t wait for a treatment plan summarises a BTO-led paper from Sam Franks and colleagues which attempts to explain the patterns we are seeing in the species’ decline.

Dotterel down 60%

IMG_2123

Alistair Baxter

Most of the information about Scotland’s breeding birds comes from annual data collected by volunteers contributing to the Breeding Bird Survey (BBS), organised by the BTO, in partnership with JNCC and RSPB. Dotterel is different; here the counts are dependent on dedicated surveys of Scotland’s high-mountain plateaus. Concern for the species is very much linked to climate change but this blog, based on a paper by the RSPB’s Daniel Hayhow and colleagues, shows that there may well be other reasons for the species decline: UK Dotterel numbers have fallen by 57%. The figure for the decline may be slightly out-of-date but the blog isn’t.

TGG OycOystercatcher down 44% *

* BBS results for Oystercatcher for 1995-2017 revise the change figure to show a decrease of 38%.

In England, the latest BBS report shows an increase of 49% in Oystercatcher numbers but, in Scotland, where there are far more breeding pairs, the species is in decline. Oystercatchers: from shingle beaches to roof-tops looks at the history of the species’ spread from the shoreline, into the hills and onto roofs and considers the role of predation in recent declines.

Golden Plover down 43% *

* BBS results for Golden Plover for 1995-2017 revise the change figure to show a decrease of 10%.

As noted in the press release about the SNH report ‘The golden plover population has declined by 43% since 1994 and stands at its lowest point since the BBS survey began. Declines may be linked to climate change, in part due to impacts on the abundance of craneflies during the breeding season”. There are two interesting papers about this by James Pearce-Higgins and colleagues.

golden ploverPearce-Higgins, J.W., Yalden, D.W. & Whittingham, M.J. 2005. Warmer springs advance the breeding phenology of golden plovers Pluvialis apricaria and their prey (Tipulidae). Oecologia 143: 470–476.

Pearce-Higgins, J.W., Dennis, P., Whittingham, M.J. & Yalden, D.W. 2010 Impacts of climate on prey abundance account for fluctuations in a population of a northern wader at the southern edge of its range. Global Change Biology 16: 12–23.

Common Sandpiper down 39% *

* BBS results for Common Sandpiper for 1995-2017 revise the change figure to show a decrease of 23%.

The Breeding Bird Survey does not properly capture trends for species found mostly along rivers. Data for Common Sandpiper are derived from the BTO Waterways Bird Survey and the Waterways Breeding Bird Survey.

Why no Redshank?

Unfortunately, breeding Redshank are now patchily distributed across Scotland, with too few being picked up by BBS surveyors to make a contribution to Scottish population indices. Across the UK, the latest published BBS decline is 38%. UK graphs for Oystercatcher, Redshank and Curlew are shown below.

UK BBS


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