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

New investigation, nonetheless, suggests a different purpose: They’re refreshing their immune systems.

In a study published in Biology Letters, researchers discovered that migratory birds increase their immune systems through 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 preferred stopover for birds on the move every single autumn.

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

Blood evaluation revealed that through the birds’ breaks on the island, their immune systems’ potential to attack bacteria and disintegrate pathogens and prospective damaging cells in the bloodstream elevated.

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

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

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

“If you see a tiny bird in your garden or in the park through 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 not recover — which is when they threat becoming ill.”