[Taxacom] snowy owl irruption and territoriality
kennethkinman at webtv.net
Mon Feb 6 21:46:34 CST 2012
I was reading more about this winter's irruption of snowy owls. It
seems to be especially concentrated into the midwestern states this time
around, even some reaching Oklahoma and Arkansas (as well as the large
numbers recorded in Kansas that I noted before).
But I am struck by the fact that there has never EVER been a
snowy owl recorded in either Arizona or New Mexico. And yet, a snowy
owl managed to make it to Bermuda at one time in the past (killed
because it was predating on the endangered cahow).
Even more shocking is the snowy owl appearing in Hawaii this past
Thanksgiving, also killed, but due to its potential threat to airplanes
at an airport. How the hell did it get to Hawaii, but none have ever
been recorded in Arizona or New Mexico. Chance dispersal to Bermuda
does not surprise me, but a dispersal to Hawaii seems so unlikely that I
can't help but wonder if it could have somehow hitched a ride on a ship
or airplane (after all, it was found at an airport on Hawaii, which is
why it was eventually shot).
Although it created some controversy, I am not overly upset about
the owl on Hawaii being shot, since there was virtually no chance that
is could have returned to its breeding grounds. But if it actually flew
to Hawaii (not a hitchhiker), it perhaps demonstrates that such vagrants
have enough energy to disperse very long distances, not starving owls
forced to disperse due to lack of food.
Seems to me more likely that they are immatures being thrust far
from southern Canada mainly by mature male snowy owls, themselves having
been thrust out of more central parts of Canada by larger female snowy
owls. Immature male owls are at the lowest end of the pecking order,
and the most likely to be displaced and forced so far afield.
Therefore, although some of these immature males might be dying from
hunger, there is also evidence that most of them are dying from
collisions with human constructs (vehicles, power lines, etc.) that are
far more common in the United States than the sparsely populated areas
of northern Canada (from whence they came).
And there seems to be no evidence that there has been any major
decreases (much less crashes) in the populations of lemmings or other
rodent prey of these owls in Canada. Therefore, I still think it is due
to a large bumper crop of snowy owls last year which resulted in
overcrowding and territorial expulsions, not a major decrease in their
food supply in Canada. -----------Ken Kinman
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