It is unusual to find a snowy owl in Wyoming because they breed in the arctic tundra and usually spend their entire lives there, but Dr. Charles Preston, the former curator of the Draper Natural History Museum, said these owls are known to erupt.
“Eruption is different from migration. Migration is a regular movement to and from North and South or East to West,” said Preston. “They [snowy owls] erupt occasionally, which is an irregular movement, not necessarily to and from a specific area, and doesn't happen every year.”
Preston said there was a great mystery about the eruption of the owls. Occasionally, they would show up in Atlanta or throughout the Rockies or even down in Mexico. So, what causes the eruption? Preston said the answer turns out to be related to food supply. A key food of the snowy owl is lemmings. They are small, mouse like creatures that live in the tundra.
“The assumption was, well the lemming population declines and then the owls spread out and look for food elsewhere,” said Preston. “But in fact, we find that these eruptions occur after a summer of a boom population of lemmings.”
This means snowy owls respond to an increase in food by producing more young. This creates a crowded situation, so in the winter some members of the population erupt or move further to the south.
“That happened in 2013 here in Wyoming,” said Preston. “This snowy owl that we have is an example of that.”