Scientists from the British Trust for Ornithology (BTO) have helped to reveal which African and European nations are linked by the birds that migrate between them each year.
The BTO staff were part of a team, led by researcher João Guilherme based at Montpellier University in France, that compared published studies of the migration routes used by 43 species travelling between Africa and Europe. They also established which countries were at either end of these journeys. These studies reviewed all used tracking technologies to follow migrant birds, where individuals are fitted with small devices that give their locations. Many species of migrant bird are declining, some precipitously so, and this new approach will allow scientists and policy-makers to pinpoint where collaboration is most needed, if we are to protect each species in both its breeding and non-breeding habitats.
Lesser Kestrel, Alcantara, Extremadura (Charlie Fleming).
This study highlights the needs of individual species and the links they create between countries, allowing conservationists to extract key information more easily. For example, although the European populations of some species, such as Swallow, were divided quite evenly across numerous sub-Saharan countries outside the breeding season, most individuals of certain other species, such as Lesser Kestrel, migrated to a single location. This information, the authors argue, can be used to direct conservation action, including protecting key locations.
Ospreys from Finland, meanwhile, were found to travel to multiple countries across Africa, while the majority of British Ospreys migrated to just Senegal and The Gambia. The fact that distinct populations of a single species take such different approaches to migration confirms that a co-ordinated, international effort is required to conserve them successfully.
BTO Senior Research Ecologist and paper author Dr Chris Hewson said: "Until now, the available tracking data on Afro-Palearctic bird migration have been fragmented, making it challenging to gain an overview of the results. By collating these data into a single resource, the overall patterns have become clearer, helping conservationists to identify which countries need to cooperate to protect vulnerable species, thus enabling us to potentially tackle declines better and to direct policy discussions more efficiently.
"Ultimately, this paper is a demonstration of what the international research community can achieve if we work together to collect and collate the necessary data."
The study also revealed that migratory destinations have been identified for only a small proportion of the total number of populations of different species. Furthermore, certain regions, such as Eastern Europe, were under-represented. Crucially, this means that many existing international links created by the unstudied species of migratory birds remain undetected. By suggesting priority species and locations for future work (eg Common Cuckoo in Poland), this study encourages the wider scientific community to fill some of these gaps and help to improve the fortunes of the planet's marvellous Afro-Palaearctic migratory birds.
You can read the full open-access article here.
Guilherme, J L, Jones, B R, Catry, I, & 7 others. 2022. Connectivity between countries established by landbirds and raptors migrating along the African-Eurasian flyway. Conservation Biology. DOI: https://doi.org/10.1111/cobi.14002