Many of the migratory songbirds that visit our shores in the summer to nest and raise their young spend the winter in the heart of Africa.
A team of ornithologists from Cardiff University have recently discovered some of the surprising survival strategies that these birds use to avoid starvation in the arid regions on the fringes of the Sahara desert. One example is an unassuming small brown bird, the reed warbler, which leads a remarkable double life.
Normally thought of as wetland species, reed warblers actually use a wide range of habitats in Africa. While some reed warblers spend the winter in wetlands, others take a different tack, opting for dry scrubland. These drier habitats, where insect prey is very scarce, represent harsh environments for reed warblers. To combat the scarcity of prey, birds feed whenever they get the chance, to build up a healthy layer of fat as insurance against starvation.
In contrast, warblers in the food rich wetlands can eat whenever they need to, so have little risk of starvation; not needing a reserve of fat they instead they remain lean all winter. As a result of these two different tactics, reed warblers are able to survive the winter whether African conditions are feast or famine, and make their epic migration back to Europe to breed.
Lead author James Vafidis said “This finding helps reveal how reed warblers survive winter during severe drought conditions, which can be so detrimental to other wetland songbirds”.
Senior author Dr Rob Thomas said “Although we often think of migratory birds that breed in the UK as “British birds”, they can also be described as African birds which visit Britain to breed. Understanding their survival behaviour in Africa is a vital part of understanding how these migrants can be protected in a rapidly changing world”.
The study was funded by the European Social Fund Knowledge Economy Skills Scholarship (KESS) in partnership with the Wildlife Trust of South and West Wales with expedition coordination by Eco-explore.
Research published in PLoS One: the Public Library of Science. http://www.plosone.org