Many birds migrate throughout the year. They’ll summer in one place and winter in another. When it comes to owls, Snowy Owls are the first thing that comes to mind when you throw around the word migration. However, what they do isn’t technically migration, it’s actually irruption.
Snowy Owls are known to do the opposite of what other migrating birds do. While most migrating birds will go back and forth to the same areas each year, Snowy Owls will usually pick different places each year. This is because their main food source, lemmings, tends to have major fluctuations in their population numbers every few years. Snowy Owls have to ensure they stay in a place that has a good food source for the season. These owls could end up in places thousands of miles away from where they were before.1
These irruptions from Snowy Owls tend to be irregular, and are more complex than a normal, predictable migration. They tend to occur every four to five years, where Snowy Owls will move into areas they don’t normally inhabit in small numbers. However, huge irruptions have occurred, where huge numbers of Snowy Owls will make their way south into new areas.2
Many think that Snowy Owls do this because they don’t have enough prey where they are, and so they come into these new areas searching for food. However, the opposite seems to be true when this occurs. These big irruptions are actually connected to an abundance of food during the breeding season.2 So instead of these irruptions being a signal that there isn’t enough food and these owls are starving, they’re actually a sign that there was a very successful breeding season up north.3
The irruptions of Snowy Owls aren’t perfectly understood. With the advance of technology, however, we’ve been able to gain more information about where they go and why. Curious about how other birds migrate? Check out our blog post here!