Hi Dave,
thanks for the interesting question about the differences between the Great
Gray and Northern Hawk Owls. While both owls in this part of the country
live primerly on voles (Microtus, which include meadow voles &
Clethrionomys, which include red-backed voles) during the summer, their
winter diet and hunting patterns are completely different during the winter.
The Great Gray is a vole specialist, hunting them year round. In the winter
they can hunt them by located them under 30cm to 60cm (1 to 2 feet) by
sound. One source said they can crash through crust on top that can support
a man, although I have heard others say that the crust prevents their
hunting. I believe their light weight supports the latter hypothesis. If
so, the formation of crust on snow cover may force them to move to other
locations to hunt.
The Hawk Owl is a visual hunter and during the winter its prey is much more
varied and includes mammals larger than the voles and birds including
grouse. In northern Minnesota I find these guys in more open habitat than
the Great Grays. Since I find some of the Hawk Owls at exactly the same
location in successive years, I suspect that like Snowy Owls, some Hawk Owls
migrate south each year drawn to locations that they have experienced
before, rather than being pushed out of areas where prey is inadequate.
In conclusion, different winter conditions and abundance of different prey
may effect the two species differently to force them out of their breeding
territories, while the southern vacation may be a greater pull to the Hawk
Owl.
Steve Weston on Quiggley Lake in Eagan, MN
swest...@comcast.net
----- Original Message -----
From: "Dave Bartkey" <greathornedd...@hotmail.com>
To: <MOU-NET@LISTS.UMN.EDU>
Sent: Wednesday, February 17, 2010 6:26 AM
Subject: [mou-net] owl question
Hi everyone,
After experiencing the great owl irruption a few years back, and then
seeing all of the Northern Hawk Owls this winter, I was wondering what the
difference is in the diet of great grays versus hawk owls? And if there is
not much difference, why the current irruption of only hawk owls? Thanks in
advance for anyone knowledgeable and willing to share!
Dave Bartkey
Faribault,MN
greathornedd...@hotmail.com
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