The global reach of WaderTales
There were 17 new WaderTales blogs in 2021. Although many have a UK focus, the map below shows the international reach of the series. The next few paragraphs summarise some of the exciting new stories that were covered during the year, using technologies as diverse as aerial surveys, satellite tracking and genetics. Many of the papers could not have been written without huge input from shorebird counters and colour-ring readers.
Many WaderTales blogs focus on migration, with more and more stories appearing as geolocators and satellite tags allow researchers to follow the whole migratory cycle. Three 2021 blogs illustrate how much there is still to learn.
Flying high with Great Snipe reveals that these amazing migrants, travelling from Sweden to the Congo basin, can achieve heights that would allow them to almost clear Everest (despite there being no need to fly this high). The paper upon which the blog is based focuses on differing altitudes of daytime and nocturnal flights. Why does a Great Snipe fly twice as high during daylight hours?
Winter conditions for Whimbrel asks whether conditions experienced in Africa affect breeding performance in Iceland. Now that researchers can study individual birds in the breeding season and wintering areas, it is becoming possible to look more closely at carry-over effects. At the end of the blog, there’s what is hopefully a helpful summary of all of the research relating to Icelandic Whimbrel.
The flock now departing reveals fascinating details about Curlew migration, with descriptions of four occasions when two tagged birds ended up in the same migratory flock. With more birds being satellite-tagged, it was only going to be a matter of time until researchers picked up cases of birds travelling together. So much food for thought in the paper at the heart of this blog!
Conservation and new technologies
There are huge conservation concerns with regard to many of the world’s waders. The next four blogs all illustrate how technological advances can help us to understand issues that are threatening shorebirds. Three were published in 2021 and the fourth includes a couple of updates to a blog from 2020.
Grassland management for Stone-curlew explains how GPS tags are revealing the preferred feeding habitats for Stone-curlews that breed in Breckland (eastern England). The creation of cultivated plots within extensive areas of grassland can provide Stone-curlews with good nesting habitat but do birds feed in these areas too? A small-scale study provided answers and showed that nesting birds are prepared to fly a long way to find food – especially to forage in pig fields.
Remote monitoring of wader habitats. Radar can be used to assess the suitability of large areas of grassland for breeding waders. The focus of the paper is upon the performance of an agri-environment scheme in Estonia, where EU funding is being directed towards breeding wader species, particularly Dunlin, Ruff, Black-tailed Godwit and Redshank. The results are of broader relevance to conservation biologists who are seeking to monitor vegetation growth and the encroachment of shrubs and trees, especially associated with a warming climate, afforestation and farmland abandonment.
Following Sociable Lapwings reveals the migration routes used by this globally-threatened species. This is vital information for conservationists who are concerned about excessive hunting of adults. Now that they know the key hotspots that are important during spring and autumn migration, as well as the areas in which birds spend the winter, it is hoped that illegal and unsustainable hunting might be reduced. Current average annual survival levels of adults are way too low. Satellite studies have revealed a previously-unknown (though suspected) third migration route.
Spoon-billed Sandpiper: track and trace was published in 2020 but has been extended to include summaries of 2021 papers, with improved population estimates (not good news) and information as to how local tracking information may be used to assess changes in habitat quality.
A focus on subspecies
Conservation priorities often relate to geographically-referenced populations or subspecies, rather than whole species. For instance, islandica Black-tailed Godwits numbers are increasing but limosa, the heartland of which is the Netherlands, is a subspecies causing huge concern. Three WaderTales blogs from 2021 focus on subspecies.
New Bar-tailed Godwit Subspecies explains why taymyrensis should be considered as two separate populations or subspecies, one of which travels from western Siberia to the Arabian Gulf. The two proposed subspecies have different migration routes and operate on different annual calendars. The newly-named yamalensis subspecies is subject to very different conservation challenges, especially in areas around the Caspian Sea and Aral Sea.
Subspecies, connectivity and conservation in shorebirds concerns the Red Knot that spend the non-breeding series in Chile, and asks whether the concept of a subspecies may distract from local conservation priorities.
Dunlin: tales from the Baltic focuses upon declines of a disappearing population of schinzii Dunlin but set in a global context. The focal paper examines long-term effects of carrying a geolocator but the potential negative effects of tracking need to be viewed in the context of a population that has dropped by 80% in 40 years. Colour-ring studies show that annual apparent survival rates of Baltic birds dropped from 0.817 to 0.650 between 1990 and 2006, equivalent to a doubling of the chance of dying in any given year.
Birds on beaches
Three of the blogs in 2021 relate to waders/shorebirds that are found on beaches
In amongst the tidewrack promotes new research into the way that roosting and resting waders make best use of microhabitats created by fresh and older beds of seaweed. The main species using this South Australian study site are Red-necked Stint and Double-banded Plover but Bar-tailed Godwit, Curlew Sandpiper, Ruddy Turnstone and Sanderling contributed data too. There’s a neat experimental set-up involving plastic golf balls!
Waders on the coast reports on the waders that winter around the open coasts of the United Kingdom, emphasising the importance of these unprotected habitats and detailing changes in numbers over 18 years. It is estimated that there are 250,000 waders on the UK’s coast but numbers of most species are lower than they were.
On the beach: breeding shorebirds and visiting tourists discusses how much space is being taken away from breeding Ringed Plovers and Oystercatchers, in Norfolk and Suffolk (UK). One of the neat features of the research at the heart of this blog is a series of aerial counts of tourists.
Two Oystercatcher papers are featured in 2021 WaderTales blogs, relating to two species with very different migratory behaviour. African Oystercatchers on Robben Island are resident, spending the time there either breeding or moulting. Most of Iceland’s Eurasian Oystercatchers migrate south for the winter, as discussed in the 2020 blog Which Icelandic Oystercatchers cross the Atlantic?
Who eats African Oystercatcher eggs? There is a complex interplay of potential predators on South Africa’s Robben Island. African Oystercatchers nesting near the Kelp Gull colony do much better than pairs that nest around the rest of the island. The gulls help to dissuade patrolling Mole Snakes, which are now the most significant predators of birds’ eggs.
Oystercatcher migration: the Dad Effect reveals that Icelandic chicks adopt the same migratory behaviour as their father (not their mother). Youngsters that cross the Atlantic migrate much later than their fathers but something about the way they are brought up must affect the ‘decision’ as to whether to migrate or not.
Conservation in the UK
Returning home, there are three blogs about the UK’s red-listed waders
England’s Black-tailed Godwits diagnoses the reasons for the recent decline in breeding numbers, following a period of rapid increase that ended in 2006. The positive message in this blog is that, if the breeding conditions are right, it is possible for the number of breeding pairs to nearly double in ten years.
More Curlew chicks needed has at its core a paper about survival rates of breeding and wintering Curlew. Even in a period of historically low annual adult mortality, UK breeding numbers have continued to fall. Based on annual survival rates of adults and current productivity, it would appear that British Curlews need to successfully fledge an extra 10,000 chicks every year – just to stop the decline in numbers.
Eleven waders on UK Red List is an update of Nine red-listed UK waders. Dunlin and Purple Sandpiper were added to the red list of Birds of Conservation Concern in 2021. The blog explains how each species has earned its place on the list.
Blogs from previous years
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.The intention is to add one or two new blogs each month. You can sign up to receive an e-mail notification when a new one is published. There’s a full list of blogs here.