The winter of 2017-18 appears to be an irruption year for snowy owls in Missouri! The birds have been spotted here and there for the past month, mostly in the northern half of Missouri, but as far south as the Golden City area. With much interest in snowy owls swirling around right now, I thought it may be useful to provide some information on the birds and provide a few resources to help birders catch a glimpse of one.
An irruption is the movement of a species outside of its regular range, oftentimes in search of food or other resources. The snowy owls’ range is in the arctic. They live year-round as far north as northern Alaska, along northern Canada and around the Hudson Bay, and breed even farther north across Nunavut (Canada’s northernmost territory) and Greenland. Snowy owls are one of the few animals tough enough to withstand arctic winters. Their main food source is lemmings, small mammals that live on the arctic tundra. Snowy owls are thought to move south during irruptions in search of food due to a shortage of lemmings in their regular arctic range. The owls that are seen this far south are generally young, first-year (hatched this past spring) birds.
The truth is, there isn’t absolute certainty in the bird world on the reason that snowy owl irruptions happen due to a lack of a large-scale dataset on the matter. However, it’s generally accepted that irruptions occur due to a resource shortage, likely food. An irruption likely occurs when the lemming population is high during the breeding season. When food is abundant, snowy owls are able to fledge many more young on the breeding grounds. In the following winter, many more juvenile owls are looking for food, and there aren’t enough lemmings to sustain them all and these young birds are forced to move south and look for food. Robbins and Otte (2013) found that a sample of snowy owls in Kansas and Missouri during the last widespread irruption in the winter of 2011-12 were emaciated and starving.
Two great resources exist to track real-time sightings of snowy owls:
Seeing a snowy owl is an amazing experience, and the excitement that these beautiful birds incite, even for non-birders, is a great way to get folks outside and interested in nature. However, if you choose to go looking for a snowy owl, be mindful of your distance. Because snowy owls this far south are presumed to be stressed and/or in search of food, they should not be disturbed. Use binoculars when viewing an owl so you don’t have to get too close, or view the owl from a vehicle, which can act as a blind. Getting too close may cause the owl to fly, forcing them to expend extra energy that they may not have if they are in poor condition. Always err on the side of caution and enjoy these beautiful birds from a distance.
Happy birding and good luck in your search!
Robbins, M. B., and C. Otte. 2013. The irruptive movement of snowy owls (Bubo scandiacus) into Kansas and Missouri during the winter of 2011-2012. Kansas Ornithological Society Bulletin, 64(4):41-44.