Researchers have been placing tiny backpack on purple martin songbirds to find out why their numbers have fallen drastically since the 1960s. They hope tracking their migration between Brazil and the Canadian province of Ontario will give them some clues.
It could be that the martins are getting to their breeding grounds in Canada on a set schedule, when in fact warming temperatures mean the insects they eat are already in decline. It appears the birds may not be immediately adapting to an earlier start to spring.
There are several species of songbirds that migrate very far south in winter that might be particularly at risk with changes in climate because they’re further away and less likely to get the signals they might need of changes up north,” says Kevin Fraser, an ecologist studying the problem at York University.