Red-backed shrikes fly thousands of kilometres to reach Africa - and they do so with astonishing precision. Aided by new technology, researchers at Lund University in Sweden have been able to track the birds' journeys in detail. It turns out that they may have a more complex genetic migration programme than researchers have previously been able to show.
"We can now follow a bird's location throughout the year. How it got there and exactly how long it took. Each bird seems to follow a precise schedule with distinct stages - and the variation between individuals is surprisingly small," says Sissel Sjöberg, evolutionary ecologist at Lund University.
Bird migration has long fascinated researchers around the world, but the details of how small migratory birds find their way across continents have been difficult to map out. Researchers already knew that birds' migratory behaviour was partly down to inherited programmes that guide direction and distance on the route. Thanks to the new technology developed in Lund, researchers have been able to follow small birds' flight in detail for the first time.
The measuring instruments, known as data loggers, weigh only one gram and can log the birds' activity around the clock throughout the entire migration. This new data provides researchers with a previously unparallelled insight into exactly how the bird carries out the flight, something that has not previously been possible for small birds.
During the spring migration, total flying time differs by only six per cent between different individuals - despite them having flown around 270 hours over the course of 43 nightly flights and covering over 11,000 kilometres.
"The results provide us with new insights into how genetics may influence small birds' long journeys across continents, and we may need to reconsider which components of migration birds inherit from their parents and how that works. Their genetic migration programme may be considerably more advanced than we previously thought," says Sissel Sjöberg.
The study provides a new dimension to the way in which genetic programmes control animals' behaviour and increase our understanding of how birds move across continents. Red-backed shrikes have turned out to be not so much adventurers as carefully prepared travellers - with a built-in flight plan that extends all the way from Skåne to southern Africa.
"It is an impressive achievement for a little bird that only weighs between 25 and 30 grams," concludes Sissel Sjöberg.
