Today’s blog is by Conservation Scientist, Tom Bradfer-Lawrence, on a new paper which will help our understanding of a long-distance migratory bird.
The spoon-billed sandpiper, or spoonies as they’re affectionately called, are a Critically Endangered shorebird species. The best recent estimate, from 2014, was that there were only about 440 adults left in the world. With such a low population, continued urgent conservation action is required to prevent their extinction.
Despite significant recent advances in understanding the migratory route used by spoon-billed sandpipers, much remains to be discovered. We only know where a fraction of the world population breeds (Chukotka, north-eastern Russia), and once they leave their breeding grounds for the winter, they could be anywhere from Russia to the Bay of Bengal.
These tiny birds are capable of travelling great distances (c) Guy Anderson
It’s not feasible to search for these tiny birds (the size of a house sparrow) across such a range without at least some idea where they might be. And without comprehensive knowledge of where the birds are, managing important sites and conservation action is very difficult.
Spoon-billed sandpipers are small, weighing around 30 g, which makes their epic twice-yearly migration all the more impressive. After breeding in North-East Russia, the birds migrate southwards for the winter. Some over-winter in China, but most continue on towards Myanmar and Bangladesh, and sightings show some travel as far as Sri Lanka. That’s over 10,000 km one way.
They are aptly named; their bills really are an unusual spoon-shape. It is thought that this adaptation might help them find and maybe filter out food items on tidal mudflats, and throughout their wintering range they are usually found in this habitat.
Threats
Such a long migration route, for such a small bird with apparently specialised habitat requirements, makes spoon-billed sandpiper vulnerable to a range of threats. The principal pressures, that we know about so far, are land reclamation and hunting. Wide-scale land reclamation has resulted in dramatic declines in the area of tidal mudflats throughout Asia, weakening links in the chain of coastal stopover locations. Invasion of mudflats in China by non-native cordgrass is rendering some of the remaining habitat unsuitable.
This habitat loss is compounded by shorebird hunting at many of the remaining sites. Hunters are generally targeting much larger species for food, spoon-billed sandpipers can sometimes be caught as by-catch.
These threats of habitat loss and hunting have contributed to a population decline of over 90% in the last fifty years, and without continued and further conservation effort, the species could easily become extinct. Fortunately, there are a large number of organisations and individuals determined to save it.
A juvenile in Tiaozini, China (c) Guy Anderson
Understanding sites
One of the key pieces of knowledge for designing conservation interventions and protecting important sites is knowing where spoon-billed sandpipers spend their time. Unfortunately, with so few individual birds and such a large potential range, there may be important sites that remain unknown and potentially unmanaged.
A new paper, published in the journal Bird Conservation International, will help to give a better picture of stopover and wintering sites. Conservation, especially of migratory species, requires international collaboration and this paper is a good example, with contributors coming from across the spoon-billed sandpiper’s range and beyond. This international group of scientists, led by RSPB staff, used computer modelling to show where spoon-billed sandpipers are most likely to be spending time when they are away from their breeding areas.
The new study updates an earlier analysis undertaken in 2012 and covers a much wider geographical area. This time round we were able to “train” the models using more records, including data from satellite-tagged birds, and utilise newer satellite remote sensing data. These satellite remote sensing data mean we can now consider more characteristics of potential wintering areas, hopefully making the models more accurate.
Results of the analysis
We found that potentially suitable areas were distributed, albeit patchily, along the entire flyway.
Predicted spoon-billed sandpiper distribution for part of its wintering range. The 5% of areas with the highest likelihood of occupancy are shown in black.
Our results show that although some wintering areas are already known, there are also a substantial number of unsurveyed sites that might be suitable for spoon-billed sandpipers, for example in parts of India, Indonesia and the Philippines.
Two categories of field surveys are needed: (i) at and near known sites – some of which are huge and very hard to survey on the ground – to determine if significant numbers of birds are currently being missed during counts, and (ii) at the potential new areas to verify the presence or absence of spoon-billed sandpipers. This field-based assessment will be the next stage of the work, and in many cases these surveys will be conducted by national BirdLife partners.
How will this help with conservation?
Overall, we hope that the findings of our study will help to guide local conservation organisations’ efforts so that they can focus monitoring and intervention work on the places that matter most. For example, during a recent sabbatical, another RSPB staff member compared our model outputs with high resolution aerial images to provide specific guidance in Vietnam for BirdLife International, who undertook surveys last winter and located an occupied site that was previously unknown.
Working together, we will be able to improve the outlook for the spoon-billed sandpiper. The RSPB and BirdLife International are members of the Spoon-billed Sandpiper Task Force, which co-ordinates conservation actions along the entire flyway to save this species from extinction and reports regularly on progress to raise awareness to the international conservation community.
For further information about spoon-billed sandpipers and to find out about the numerous interventions taking place, see the Task Force newsletters and the Saving Spoon-billed Sandpiper website.
For the full paper in Bird Conservation international: Modelling the potential non-breeding distribution of Spoon-billed Sandpiper Calidris pygmaea.
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