Migrating birds can cover 300 miles a day and undertake journeys of thousands of miles, but scientists have always wondered how the birds know when, where and how far to fly.
Some of the answers must lie in the birds' DNA, they knew, and now ornithologists at the Max Planck Institute for Ornithology in Starnberg, Germany, have studied European blackcaps, a common warbler, in an effort to track down a migration gene.
The researchers focused on six genes known to influence how active a bird is at night or how much it tends to hop from branch to branch as it explores its environment.
As migration approaches, birds bulk up, adding muscle and fat, and hop and flap restlessly at night, shifting their internal clocks in anticipation of nighttime flights.
Comparing genes in different populations of blackcaps that exhibited variations in these behaviors, the researchers found a link to just one gene, called ADCYAP1, and found that variation in the gene correlated with variations in how much the birds hopped and flapped around their cages at night.
This gene influences daily rhythms and affects energy use, increasing body temperature, metabolic rate, and fat usage – just the sorts of changes that occur as a bird gets ready to migrate.
"It is the first demonstration," researcher Francisco Pulidso says, "of a specific gene that is important for the expression of migratory behavior in birds."