for National Geographic News
Like avid travelers picking up local languages, migrating birds appear to learn and understand the common calls of unrelated bird species that they encounter during their long journeys, new research reveals.
Birds that remain in one location throughout the year have no difficulty identifying predators, such as hawks, ferrets, and snakes.
Migrators, however, constantly face the threat of encountering predators in their travels that they do not immediately recognize as dangerous.
"When I first came to the jungle in Belize I was overwhelmed by the diversity of snakes," said study author Joe Nocera of Queen's University.
"I realized I couldn't spend my whole day avoiding every snake I saw," he said. "I just had to learn from the locals which ones were dangerous.
"This made me wonder how migrant birds, which were just as naïve as me, dealt with this. I suspected they must be learning from the locals too."
Some ecologists had previously suggested that long-distance travelers pick up cues from local species to obtain information on unfamiliar predators, but evidence for this theory has been thin.
To explore the possibility, researchers at Queen's University in Ontario, Canada, played predator warning calls made by both local and foreign species to birds passing through Belize on long migrations as well as to local birds and monitored their reactions.
The study appears in this month's issue of Behavioral Ecology and Sociobiology.
It is also along the main migratory route of 83 bird species that fly south from North America for the winter. While some of these birds finish their migrations in Belize, some continue on toward South America.