Long-distance migratory patterns of birds follow peaks in resources

COPENHAGEN, Denmark, Jan. 4 (UPI) -- According to a new study, the cross-continent migratory routes of birds follow the apex of resource abundance at various stopover points.

Researchers followed the migratory paths of common cuckoos, red-backed shrikes and thrush nightingales, and found all three species plot their way across sub-Saharan Africa so their migration is in sync with seasonal vegetation changes.

Satellite tags helped scientists track the paths of the birds from Europe to Africa and back again. The imagery revealed complex routes correlated with peaks in green vegetation. Presumably, peak greening corresponds with abundant food availability.

Scientists believe these routes are based on many generations of experience, forging a link between their migratory movements and places that have offered abundant resources throughout their evolutionary history. How quickly birds can adapt isn't clear.

Researchers used climate models to understand how shifts in vegetation patterns could throw off long-established migratory patterns. By 2080, scientists found significant differences between the current expectations of migratory bird species and future projections of seasonal food availability.

"We believe that bird's innate programme to guide them over long distances, must be adapted to long-term average of food availability," Carsten Rahbek, an ecologist at the University of Copenhagen, said in a news release. "Our results suggest that by the end of this century climate change, and other impacts on the food source, like land use changes, could negatively influence the birds' chances to find sufficient food."

The new research was published in the journal Science Advances.