Birders, I'll preface this response with what I am saying is by no means scientific fact and is theory at this point. I've gathered some ideas from ebird and other places, as well as my experience.
To add on to AJ's great response, arctic scientists have an unexpected theory on why so many snowies are heading south. As Ann said, food shortage is typically the cause for birds to be desperate enough to fly this far for a meal. However, this year the population level of their food source (lemmings) was at a historical high. In nature, this usually results in highly successful reproduction rates of the consumer. Such was the case of snowy owls, resulting in an over-saturation of birds on winter hunting grounds. For the most part, it will be young birds being forced to go find new hunting grounds, which is what we've been seeing a lot of here. There certainly are plenty of small mammals here in Iowa during an average winter, but these inexperienced hunters have only known lemmings, which we do not have. Also, as Ann mentioned, they have already expended SO much energy in making their way here, that they probably aren't at the top of their game when they arrive. I spoke with raptor rehabilitator, Kay Neumann this afternoon. She received a struggling snowy owl from the Humbolt area that ended up dying in her care. When she weighed it, it only weighed 2lbs when it should weigh 4lbs. As unfortunate as it is seeing owls die, by the theory of why we think they are here this year, you can assume that the overall snowy owl population won't take a hit. It will only be the best hunters of this new crop of owls that will survive the winter and make their way back north. So again, in a way it is food shortage, but it seems to be because there are too many owls for the carrying capacity of their normal habitat. Not necessarily pleasant to accept for many folks, but it is part of nature's balancing act. I hope this helps and even makes you more curious to ask questions, as well as hungry (no pun intended...maybe) to get out and watch Iowa's birds. Bird on... matt Matthew T. Wetrich Naturalist, Carroll County Conservation (712) 210-4614 Sent from my U.S. Cellular BlackBerry® smartphone
