Teenage waders

Hudsonian Godwit in breeding plumage

A paper by Juan Navedo & Jorge Ruiz, focusing on Hudsonian Godwits, raises important points about the conservation of the world’s larger shorebirds.

Many curlews and godwits don’t breed in their first year but what do they do instead and how quickly do individuals recruit into the breeding population? These answers have direct implications for the conservation of these species, numbers of which are declining in most cases.

Hudsonian Godwits

Hudsonian Godwits breed in Alaska and Canada and spend the non-breeding season in Chile and Argentina. There are three well-separated breeding populations; in south-central and western Alaska, along the northwest coast of Canada (Mackenzie and Anderson river deltas) and within the Hudson and James Bay region of northern Canada. These are indicated in the figure alongside, based on the map from BirdLife International’s datazone.

On migration, Hudsonian Godwits do not use coastal areas, which led to the theory that their journeys north and south might be made without a break. Satellite tracking has revealed that staging areas are continental rather than coastal. The latest research shows that birds wintering in Chile stop off in the prairies of North America on the way north. On the return journey, there are key refuelling areas in Saskatchewan (Canada) and in continental wetlands between Colombia and Argentina. Map below is from a paper from Senner et al.

Satellite tracking of two birds from the Mackenzie Delta breeding population, on Canada’s Arctic coast, revealed a 1500 mile two-day ‘hop’ to Hudson Bay, a long refuelling and moulting period and then a 4 or 5 day direct flight to South America. These are very impressive migrants!

As discussed in Why are we losing our large waders?, the Hudsonian Godwit is still considered to be of ‘least concern’ on the IUCN/BirdLife list. The fact that the species breeds over a broad sweep of Alaska and Canada, even if in discrete areas, and that the population, estimated to be 77,000 individuals (Andres et al 2012), is well over the 10,000 cut-off for threat consideration, means that the species is not yet designated as being of international concern. In Canada, Hudsonian Godwit was added to the ‘threatened species’ list in 2019, as a consequence of reduced breeding success and a major decline in the Canadian breeding population. The latest population estimate in the COSEWIC report is that there are just 41,000 mature individuals (24,300 in the Hudson Bay Lowlands, 800 in the Mackenzie Delta, and 15,750 in Alaska).

Non-breeding youngsters

Releasing a satellite-tagged Hudsonian Godwit

When Hudsonian Godwits depart from the coasts of Chile and Argentina, on their way to Alaska and Canada, they leave behind young birds that will not breed in their first year – and possibly even the second or third. These sub-adults are the future of Hudsonian Godwit conservation. In a declining population, it is important that as many as possible of these youngsters will reach maturity and breed successfully.

Juan Navedo, Jorge Ruiz and colleagues from Universidad Austral de Chile, have been studying the ecology and migratory behaviour of Hudsonian Godwits that winter in Chiloé Island (c. 32°S, Chile) as summarised here. One of the unexpected outcomes of this work is a 2020 paper in Global Ecology and Conservation, entitled Oversummering in the southern hemisphere by long-distance migratory shorebirds calls for reappraisal of wetland conservation policies. In it, they followed the movements of a small number of satellite-tagged adults and discovered significant flocks of non-breeding birds. Their great detective work has clear implications for the potential recovery of Hudsonian Godwit populations and wider consequences for other species of shorebirds that don’t breed in their early year or years of life.

Spring departure

Hudsonian Godwits in Chile are being tracked to improve understanding of the connectivity between their discrete breeding areas and their wintering areas. Tracing their journeys also helps to establish the refuelling areas that are used during northwards and southwards migration.

When it was time to depart from Chiloé Island in spring, most adult Hudsonian Godwits spent a week flying north non-stop over the Pacific, crossed Mexico and staged in the plains of North America but, in 2017, three tagged birds unexpectedly headed northeast to the Pampa wetlands of Argentina. These birds all remained in the Pampa area for five or more months. Their tags provided positions every thirty minutes, supplying the scientists with the information they needed to identify key ‘oversummering’ areas for the species. By focusing on groups of locations for two of the tagged birds, it was possible to identify a 28,000 km2 area that seemed to be of particular importance. Was this where young Hudsonian Godwits (not wearing tags) spent the same period?

The paper explains how the team searched the vast area of permanent and ephemeral wetlands in a systematic way, allowing estimates to be made of the number of shorebirds of a range of species that spend time in this area, instead of migrating north to breed. Hudsonian Godwits were found in four (out of 44) wetlands in 2018 and three in 2019, making a total of 366 and 746 individuals in the two years.

Looking for Hudsonian Godwits in the Pampa Wetlands of Argentina

In their three-day surveys, the team was only able to survey a small number of potential feeding sites within the vast area. On the assumption that Hudsonian Godwits mature at the same rate as other large, long-distance migrant waders, such as limosa Black-tailed Godwits and baueri Bar-tailed Godwits, Juan Navedo and Jorge Ruiz suggest that nearly half of first-year, a quarter of second-year and 15% of third-year Hudsonian Godwits may be using these continental wetlands during a crucial stage of their lives. Numbers of Lesser Yellowlegs and Greater Yellowlegs that they found in the same habitats were also of conservation significance, and the Pampa wetlands are also a ‘summering’ area for Buff-breasted Sandpiper and Upland Sandpiper.

Conservation implications for Hudsonian Godwits

Young Hudsonian Godwits will hopefully breed in Alaska in later years

The paper by Juan Navedo & Jorge Ruiz clearly demonstrates the significance of the Pampa wetlands for waders that were raised in the Northern Hemisphere but which don’t return there until their second, third or even fourth potential breeding season. What is it about these wetlands that is so important to young Hudsonian Godwits, how vulnerable are they and what other inland areas are being used by flocks of young birds? The authors point out that the pampas habitats of Argentina are changing. The Pampa wetlands are being turned into vast swaths of agricultural land, much of which is being planted with herbicide-resistant transgenic soybean. Globally, it is estimated that 77% of soybean is grown to supply animal feed. This is a thirsty crop that requires irrigation, sucking water out of the remaining wetlands. These grassland habitats are subject to a Memorandum of Understanding on the Conservation of Southern South American Migratory Grassland Bird Species and Their Habitats.

Flagged Hudsonian Godwit

The presence of some adult birds in the Pampa wetlands flocks is not surprising. As discussed and referenced in the paper, individuals that migrate long distances and that are on tight schedules may need to skip the occasional breeding season if they do not have sufficient fat reserves to head north on schedule. When studying tracked individuals of migratory shorebirds that undertake long, non-stop flights, it has been shown that birds occasionally abort their journeys if they encounter adverse weather conditions. We know that godwits of other species can live for thirty years or more so there is always next year.

Wider implications

The Hudsonian Godwit paper is not just about one species. It asks important questions about the conservation of waders and other families of birds that do not breed in their first year. Globally, have we identified the most important shorebird sites, can we protect them from development and are some sites more important than others? Do we pay these sites enough attention in the breeding season, when the large swirling flocks have departed, leaving much smaller aggregations of non-breeding birds sparsely distributesd throughout flyways? Protecting these small oversummering flocks is investing in the future of threatened wader species.

Site protection: This paper has highlighted an important issue. What do young curlews, godwits and other large and medium-sized waders do in the ‘teenage’ years – that important period between being a juvenile and being a breeding adult? Where are they? Are the sites protected? Do birds simply stay in the areas in which they settle in August, September or October, after they have flown south from the breeding grounds? The Pampa wetlands of Argentina are unlikely to be the only non-coastal areas that are used by young waders; what other sites are we missing? For Hudsonian Godwits, perhaps there needs to be a broader definition of key shorebird areas when considering candidate sites that need to be protected as part of the excellent Western Hemisphere Shorebird Reserve Network? More broadly, the authors propose that conservation agreements regarding wetlands of international concern should include a specific criterion for oversummering areas.

Figure illustrating delayed maturity of Hudsonian Godwits (from Navedo & Ruiz)

Youth clubs: Young waders recruit to the breeding population at different ages. If the typical life expectancy of a godwit is ten years then a bird that flies north in its second summer will, on average, produce 12% more chicks in its life-time than one that does not breed until a year later. Hudsonian Godwits not only need to survive in these Pampa youth clubs, they also need to thrive.

Within the same species, time of first breeding can be influenced by the non-breeding site than an individual happens to use. In their fascinating paper about Sanderling migration, summarised in the WaderTales blog Travel advice for Sanderling, Jeroen Reneerkens and colleagues showed large difference in the proportion of young birds that travelled north in the first summer. Most Sanderling that spend the winter in England and Portugal fly to Greenland in spring but only a tiny proportion of birds wintering in Ghana have this extra breeding attempt. They link these differences to site quality.

Eurasian Curlew and a young Black-tailed Godwit

Disturbance: When the number of Eurasian Curlew on a British or Irish estuary drops rapidly, in March and April, and when adult Far Eastern Curlew leave Australia to head for eastern Russia, do we pay enough attention to the small number of birds that remain?

In the northern hemisphere, in particular, the summer months of May through to July bring increased disturbance pressure to beaches and to estuaries, at a time when non-breeding waders are trying to find the resources they need to undertake their primary moult. Perhaps more thought needs to be given to zoning recreational activities in areas which are internationally designated as conservation areas? A May count of 27 Eurasian Curlew on the Exe Estuary in Devon may seem trivial, when compared to 849 in August (Wetland Bird Survey 2018), but these birds represent the future.

In summary

As Juan Navedo & Jorge Ruizwrite in the abstract of their paper:

Given their delayed maturity, many long-distance migratory shorebirds may spend large portions of their lives in previously undocumented wetlands, while deferring migration. These unrecognized oversummering habitats fall outside the scope of today’s conservation efforts for Hudsonian Godwits, because they are not spatially nested within the non-breeding grounds, an issue to be studied for other shorebirds.

We are seeing rapid declines of many of the Numeniini family (see this blog about curlews, godwits and Upland Sandpiper) and other slow-maturing shorebird species, and ‘teenage birds’ deserve more attention. We have to identify the areas used by immature birds as quickly as possible, before productivity is so low that we cannot find them.

Oversummering in the southern hemisphere by long-distance migratory shorebirds calls for reappraisal of wetland conservation policies. Juan G. Navedo & Jorge Ruiz. Global Ecology and Conservation doi.org/10.1016/j.gecco.2020.e01189

Wintering Hudsonian Godwits on Chiloé Island, Chile.

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

Cycling for waders

This blog is mostly about Black-tailed Godwits but there’s stuff about cycling too!

If you’re a Black-tailed Godwit, a 2800-mile (4500-km) direct flight from East Anglia to West Africa is estimated to burn 1085 Calories (4500 kJ) of energy (Alves & Lourenço). Fuelled by Cambridgeshire worms, a female godwit that was raised by the Project Godwit head-starting team flew from the Nene Washes to wetlands in south-east Mauritania in just two days. ‘Cornelia’ – as she was named – undertook this marathon journey with no pre-season training. She just took off on 13th August and arrived on the 15th.

To raise money for Project Godwit and for research projects funded by the International Wader Study Group, Jen and Mark Smart cycled from Somerset to East Anglia, on a 600 mile (960 km) journey that links sites that have been visited by head-started Black-tailed Godwit chicks. Each of them burnt 15,000 Calories (62,800 kJ) over the course of eight days, taking in high energy foods as they travel and stopping to feed and rest each night. Unlike Cornelia, Mark and Jen had been training for years.

Quick reminder of head-starting

Black-tailed Godwits breeding in East Anglia face huge challenges, as you can read below. Four years ago, their situation had become so perilous that it was decided that the only way to stop them disappearing completely was to hatch eggs in incubators and raise chicks in captivity. You can read more about head-starting here. Project Godwit is a partnership between RSPB and WWT, with major funding from the EU LIFE Nature Programme, the HSBC 150th Anniversary Fund, Natural England, the National Lottery Heritage Fund through the Back from the Brink Programme, Leica and the Montague-Panton Animal Welfare Trust.

The maps below show the two breeding sites (Ouse and Nene Washes) and all the late-summer passage sites where head-started birds have been seen in England (left), and the international sightings of all godwits ringed in these breeding sites.

International Wader Study Group (IWSG)

The International Wader Study Group brings together everyone who has a passion for waders (shorebirds), the habitats they use and their conservation. Members include research scientists, citizen scientists and conservation practitioners from all around the world. IWSG gives out small grants each year that help to support wader projects around the world. Recent grants have been used to discover the wintering areas of Common Sandpipers, to measure the site-faithfulness of Dotterel and to support projects in Azerbaijan, Albania, Bangladesh & Argentina.

Mark and Jen

Jen Smart has worked for the RSPB for 14 years.  As a scientist, she led RSPB’s research into the conservation problems faced by breeding waders and developed solutions to help these species. See the WaderTales blog Tool-kit for wader conservation. She developed the science programme around Project Godwit and maintains a keen interest in the project. Jen is Chair of the International Wader Study Group.

‘Manea’ arrived at Old Hall Marshes (Kent) with his sister, ‘Lady’, in July 2017

Mark has worked for the RSPB for 26 years and is Senior Site Manager at Berney Marshes, a 600 ha grassland nature reserve with around 300 pairs of breeding waders. See the WaderTales blog Managing water for waders. As well as managing the reserve, Mark works with other land managers across the country to develop and implement ways of improving habitats for breeding waders.

Latest news from Project Godwit

Project Godwit has been trialling the use of head-starting (https://projectgodwit.org.uk/), where young godwits are reared in captivity, safe from predators and potential flooding, and released once fledged. The aim is to boost the number of godwits breeding in England. The cycle route for Mark and Jen links eleven nature reserves in England, managed by a range of conservation organisations, where head-started Black-tailed Godwits have been spotted on migration by local birdwatchers.

Nelson is one of the birds carrying a geolocator but he has not been recaught (yet)

The ride started at WWT Steart Marshes in Somerset; visited by a Black-tailed Godwit named ‘Nelson’ in 2017. Birdwatchers throughout England were put on alert when the first head-started Black-tailed Godwits were released in 2017 but it was a surprise when Nelson headed southwest. Nelson is a star of Project Godwit. He returned to the Ouse Washes in 2018 and paired up with another head-started bird called ‘Lady’. They have met up in each subsequent spring. In February, Nelson spends time on the Tagus Estuary in Portugal but we don’t know whether he is one of the limosa Black-tailed Godwits that winters south of the Sahara.

The map below shows the route taken by Mark and Jen. The original plan was to cycle from Norfolk to the IWSG conference in Germany, which neatly linked the two causes for which they are seeking sponsorship – Project Godwit and the IWSG fund to support wader research. When the conference was rescheduled as an on-line meeting, they decided to join up the godwit dots across England. The 600-mile bike took just over a week.

Jen & Mark’s route links RSPB, WWT, Wildlife Trustand county wildlife sites between Somerset and Cambridgeshire.

The last site to be visited was the Nene Washes where, as mentioned above, the Black-tailed Godwit ‘Cornelia’ returned to breed. Having been raised at Welney, she was released at the Nene Washes on 27 June, 2018, wearing a small geolocator attached to a flag on her lime ring (see earlier picture). She is the only bird for which the RSPB and WWT team have a whole-year migration history. Cornelia was caught on a nest at the Nene Washes in 2019 and her geolocator was removed. In his blog on the Back from the Brink website, Mo Verhoeven shares his excitement when he learned that this young bird had flown directly from the Nene Washes to wetlands in Mauritania in just two days. There is more about Cornelia here.

Conservation challenges

Wetlands are under threat across the globe and it is appropriate that Mark and Jen are raising money for the International Wader Study Group and for Project Godwit. As they tweeted about their travels and talked about Black-tailed Godwits at local press events, at different nature reserves, they revealed some of the conservation challenges that waders face.

The RSPB nature reserve at Titchwell (North Norfolk) is a favourite pit-stop for Project Godwit birds. These three youngsters, all head-started in 2018, visited before flying south.

Project Godwit is not just about head-starting more Black-tailed Godwit chicks. The team is trying to improve the chances for nesting birds out on the Washes, using electric fences and other predation reduction schemes, and through the development of alternative breeding areas that are under less threat of flooding during spring and summer deluges.

Within Britain and when they head south through Europe and into Africa, Black-tailed Godwits are dependent upon a network of sites. Some of them are fully-protected nature reserves, others have been given international recognition as SPAs and Ramsar sites, but there are many other locations that are important but not designated. Sightings of Project Godwit birds and locations downloaded from geolocators will help to identify areas in which birds may be vulnerable to habitat change and new developments.

A new airport that is planned for the Tagus Estuary is a huge threat to limosa Black-tailed Godwits that breed in Western Europe, including the small English population. It’s thought that about half of the Project Godwit birds use the rice fields and mudflats of the Tagus Estuary, as you can read in Black-tailed Godwits are on their way home. As mentioned above, Nelson has been seen in the Tagus Estuary on several occasions (see map alongside). The proposed airport threatens many species of migrant waterbirds (Tagus Estuary: for birds or planes).

An important unknown when trying to conserve our larger wader species is ‘what happens to the teenagers?’. When do species such as Black-tailed Godwits start to breed and what do they do in the period between fledging and breeding? A key part of Project Godwit is to mark chicks in the wild, as well as head-started birds, hopefully answering questions such as ‘what proportion breed in their first year?’ and ‘where do immature birds spend the pre-breeding years’? Perhaps the International wader Study Group will be able to support similar work for other large shorebird species, through its small project grants?

Support for Mark and Jen

This epic sponsored cycle ride is funding work by Project Godwit and the IWSG. It was a great opportunity to thank colour-ring readers who have reported marked birds, to emphasise the importance of protecting networks of sites for migrant waders, and to highlight some of the conservation challenges that lie ahead.

If you would like to help Mark and Jen to support International Wader Study Group Small Projects Grants, please donate here: https://www.waderstudygroup.org/donate/

If you would like to help Mark and Jen to support the RSPB’s contribution to Project Godwit please donate here: https://www.justgiving.com/fundraising/fundsforwaders


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