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Lu,
The problem with the barn owls is likely a combination of starvation and
cold stress. The two problems go hand in hand. All the deep snow has
hampered their ability to get small rodents running along the ground (mainly
voles). This, coupled with the fact that it has been unusually cold,
they have to spend more energy maintaining their body temperature (a double
whammy).
Barn Owls are just not adapted to these kinds of conditions. They
have a much lower insulative value to their plumage then other owls and
consequently their zone of thermoneutrality (range of ambient temperatures the
bird can stand before they have to begin increasing metabolic rate to maintain
body temperature) is very narrow.
If you look at their winter distribution you can see that northern
Utah is along the northern most extent of their range and they don't occupy
regions that typically experience these kinds of conditions every year (e.g. you
don't find them in Montana). The owls that winter here are gambling
that conditions will be suitable for them. In most years it is a safe bet
but when they are wrong its deadly!
Carl Marti and Phil Wagner reported a similar occurrence of severe
winter mortality here in northern Utah back during the winter of 1981 -
1982.
The upshot of all this is that because young barn owls have a very high
dispersal rate, the population shouldn't be affected for too long.
Cheers
JFC
John F. Cavitt PhD
Dept. of Zoology Weber State University 2505 University Circle Ogden, UT 84408-2505 "A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise." Aldo Leopold >>> "L. D. Giddings" <seldom74@xmission.com> 1/8/2004 10:46:23 PM >>> Betsy,
when I visited Antelope Island yesterday I stopped at the Visitor's Center and chatted with ranger for a while. He mentioned that they found one of the Garr ranch barn owls dead the other day. If this is wide-spread, it seems unlikely to be attributable to a single source of poisons or toxins, or to a lone act of malicious mischief. Is it possible that an avian epidemic or cold stress is responsible? Do you - or any of the rest of you - have any sense of which cites/counties have been affected? Have any of you seen anything like this before? Lu Giddings Betsy_Beneke@fws.gov wrote: > Hello Utah birders! > > Since we've had all the snow, refuge staff have been finding, or taking > calls from local residents, about dead or dying barn owls. We've taken a > couple to the Ogden Nature Center. > > I was just wondering if other folks are hearing about barn owls that are in > trouble. I wish we could do something to help them... > > Betsy Beneke > Outdoor Recreation Planner > Bear River Migratory Bird Refuge > Box Elder County > > _______________________________________________ > > "Utah Birds" web site: http://www.utahbirds.org > BirdTalk: > To subscribe, e-mail: birdtalk-subscribe@utahbirds.org > To unsubscribe, e-mail: birdtalk-unsubscribe@utahbirds.org > To send a message, e-mail: birdtalk@utahbirds.org > _________________________________________________ _______________________________________________ "Utah Birds" web site: http://www.utahbirds.org BirdTalk: To subscribe, e-mail: birdtalk-subscribe@utahbirds.org To unsubscribe, e-mail: birdtalk-unsubscribe@utahbirds.org To send a message, e-mail: birdtalk@utahbirds.org _________________________________________________ |