Conventional wisdom holds that Snowy Owls are forced south in winter by a lack of prey in the Arctic, and therefore are starving. But researchers Alexander Chang and Karen Wiebe beg to differ.
They studied the body condition and relative mortality of 537 owls captured in south-central Saskatchewan over 18 frigid field seasons and published their findings in a recent issue of the journal The Auk: Ornithological Advances.
They learned not only that females tend to be in better condition than males, and that adults tend to be in better condition than juveniles, but also that few of the adults show signs of starvation.
Chang and Wiebe speculate that adult Snowies are able to build up or at least maintain their energy reserves because they are experienced hunters, and well insulated against the cold.
“Furthermore, winter is a time when they are not engaged in energetically costly activities such as reproduction,” they write. “Thus, given sufficient food sources, winter may actually be a time for Snowy Owls on the prairies to increase energy stores prior to migration, especially in adult females preparing for reproduction.”
Read the abstract
Alexander M. Chang and Karen L. Wiebe (2016). Body Condition in Snowy Owls Wintering on the Prairies Is Greater in Females and Older Individuals and May Contribute to Sex-based Mortality. The Auk: Ornithological Advances, Volume 133, pp. 738–746.
eBird maps show Snowy Owl’s summer and winter ranges.
10 photos of enigmatic, irruptive Snowy Owls.
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