[Taxacom] Hypothesis about another irruption of snowy owls into U.S.
kinman at hotmail.com
Fri Dec 13 19:56:47 CST 2013
Just two years after the big snowy owl irruption of 2011-2012, another one is now making news across the eastern U.S. (even here in Kansas). Anyway, it is my increasing suspicion that these irruptions of snowy owls into the United States might become quite frequent. Although much is said about their population numbers depending on the populations of their prey (especially lemmings), not much is said about the effects of predation on snowy owls themselves (especially the chicks).
One of the few predators of snowy owl chicks which the parents are unable to chase off is the polar bear. As polar bear numbers decrease, they will eat less snowy owl chicks, and snowy owl populations can quickly increase in years when there is plenty for them to eat. But then the lemming population will tend to crash even more quickly, and the excess snowy owls must then fly south for food.
Anyway, with fewer polar bears to keep the snowy owl population in check, I think the population booms and busts of both snowy owls and lemmings will become more frequent and severe. Some have claimed that polar bear populations are actually increasing, but I suspect that the bears are just invading human settlements more often in search of easy food in garbage dumps. Scavenging polar bears could be increasing, while the total population is decreasing. The whole ecosystem is out of balance.
Thus snowy owl irruptions into the United States could become larger and more frequent. Therefore, I don't think the more frequent irruptions are as puzzling as some make it, if only they would look past other hypotheses (weather patterns or lemming population fluctuations) and look at decreased predation upon snowy owl nests as a primary factor.
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