Snowy owls have descended on the Great Lakes region and northeastern U.S. in huge numbers in recent weeks, to the delight of birdwatchers.
The mass migration we’re seeing this winter is what’s known as an irruption.
"For snowies, that's usually largely influenced by whether or not they had a really good breeding year,” said Rachelle Roake, a conservation scientist at Michigan Audubon.
And snowy owl breeding is influenced by how much food those snowy owls have access to during the breeding season.