Researchers when believed that when birds took breaks on lengthy migration routes, they had been stopping to develop up their fat reserves for the rest of their journey.

New study, on the other hand, suggests yet another explanation: They’re refreshing their immune systems.

In a study published in Biology Letters, researchers located that migratory birds increase their immune systems for the duration of breaks from marathon flights. In fall 2021, they studied typical redstart, chaffinch and dunnock on Helgoland, an island off the German coast along the North Sea that is a well-liked stopover for birds on the move every autumn.

Researchers captured, tagged and released birds on the island quite a few instances a day for the duration of the study. They ended up sampling the blood of 96 birds two instances every more than the stopovers, which ranged from an hour in some circumstances to a small more than two weeks.

Blood evaluation revealed that for the duration of the birds’ breaks on the island, their immune systems’ capability to attack bacteria and disintegrate pathogens and prospective damaging cells in the bloodstream improved.

Researchers say the gains weren’t connected to the birds’ fat levels. Rather, they think the immune boosts had been due to a substantially-necessary break from the strains of marathon migrations.

Migrations are “truly intense physical activity,” they create, and aside from the physical exertion needed, birds’ travels take them into new habitats and expose them to a wide variety of pathogens.

In a news release, the researchers evaluate the stopovers to pit stops at service stations — rests that refuel automobiles and refresh their drivers.

“If you see a small bird in your garden or in the park for the duration of the autumn and you know that it is heading to southern Europe or Africa, it is fascinating to believe about why it is taking a break,” Arne Hegemann, a biologist at Lund University in Sweden and a co-author of the study, mentioned in the release. “If they do not get meals or rest, their immune systems can’t recover — which is when they danger becoming ill.”