Researchers examined small Eurasian migratory birds – such as Common Redstarts, Dunnocks, and Common Chaffinches – to analyze how their immune system changes when they make a migration stopover (Common Redstart by Ferit Basbug).

After a prolonged period of physical exertion, birds and other vertebrates usually need a period of recovery. During migrations, birds need to rest to renew their energy levels, and new research shows that stopovers also give them the chance to boost their immune system. Apart from obvious things like reducing their heart rate and resting muscles, other less prominent physiological systems also need to recover; for example, intensive physical activity like migrating flights can affect a bird’s basic immune system defense.

When birds migrate, they regularly stop at one location for a few days to rest and eat. These stopovers were previously thought to be necessary to build up fat deposits that provide energy for their migration flights. However, researchers have now learned that birds also build up their immune system during their migration stopovers. Birds can do this very quickly – a few days’ rest appears to be enough.

“This is the first time that this has been demonstrated in wild migratory birds. Our study shows that migratory birds’ stops serve other purposes, besides just ‘re-fueling.’ They also need other physiological systems to recover. You could compare it to pulling off the motorway into a service station. That is not just for the purpose of re-fueling, you might also need to recover,” explained Arne Hegemann, biologist at Lund University in Sweden, who conducted the study with colleagues from the Institute for Avian Research in Germany.

Researchers examined small Eurasian migratory birds – such as Common Chaffinches, Dunnocks, and Common Redstarts – to analyze how their immune system changes when they take a break during migration. “If you see a bird in your garden or in the park during autumn and you know that it is heading to southern Europe or Africa, it is fascinating to think about why it is taking a break. If they do not get food or rest, their immune systems cannot recover, which is when they risk becoming ill,” said Hegemann.

By collecting and comparing data from different individuals and different species, the researchers showed that migratory birds can restore several parameters of immune function during stopovers between flights.

“It is fascinating just how much we are still to learn about avian migration and exciting new things emerge regularly. This provides an important part of the puzzle of how migratory birds cope with the physiological challenges they are faced with on their long migrations,” concluded Hegemann.

To refer to the original article, published in ScienceDaily, see Migratory birds take breaks to boost their immune system -- ScienceDaily