[CT Birds] Hawks-Owl & prey

Anthony Zemba Anthony.Zemba at gza.com
Fri Jan 28 13:43:14 EST 2011


I, too, find all this discussion extremely interesting.  Though, I am not surprised by the reports of seeming prey shifts exhibited by the raptors. I once returned home late at night to see a Barred Owl sitting on my road (at the time when I lived there - Westford Hill Road in Ashford) in March intently watching Spring Peepers crossing the road which bisected a swamp. I watched it in the headlights of my car as it easily picked off the peepers trying to run (hop?) the gauntlet.  Also, just look at the list of prey items listed for Red-tailed Hawk and esp. for Great Horned Owl in Terres (1980).  Upon reading the quite lengthy list of Great Horned Owl prey I can't help but think of the time Bugs Bunny was reading in a book all the prey species that Tasmanian Devils eat (while TAZ was looking over his shoulder) and after reciting quite a lengthy list of spp. he says "What? No Rabbits?!" then TAZ reaches over and turns the page and there in enlarged font is written: AND ESPECIALLY RABBITS!!!

Anthony J. Zemba CHMM
Senior Project Manager/Ecologist
Professional Soil Scientist
GZA GeoEnvironmental, Inc.

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-----Original Message-----
From: ctbirds-bounces at lists.ctbirding.org [mailto:ctbirds-bounces at lists.ctbirding.org] On Behalf Of Carrier Graphics
Sent: Friday, January 28, 2011 12:02 PM
To: ctbirds at lists.ctbirding.org
Subject: [CT Birds] Hawks-Owl & prey

I find the discussions on this site about predators and prey of great interest.
This winter seems to be a difficult time for both predators and prey. Snow depth
and cold can be part of the problem, but i believe nature has given birds and
their predators millions of years of trial and error to overcome these seemingly
devastating conditions.


If I may, I have written several examples I have observed over the years that
might show how these stressed birds overcome these weather situations, and i
would be pleased to see others examples that might shed some light on this
subject as well.

First. I know mice and other small animals do conceal themselves under the snow
pack, but they do occasionally come out to explore on the surface as well. This
fact can be seen from mouse and other animals tracts upon the snows surface. I
often see mouse tracts on the snow going from bush to bush or other objects.
Many other larger mammals use the snow surface for travel such as Squirrels,
Rabbits etc.


Also as mentioned, wherever the prey birds congregate, also do the predators.
And, when the times get difficult, many predators can and will change their food
of choice to other prey. Some Examples:

I have noticed several times during a deep snowy winter, the Barred Owls in my
back woods will perch in a tree observing the many feeder birds as the day turns
to darkness. They will notice where the small birds- esp Juncos - go to roost,
which is usually within the lower snow covered hemlock branches touching the
snow surface. When it becomes dark, the owl will fly down to this site and go in
for breakfast. This observation Illustrates how a predator will change it's
preferred prey to one that is much more abundant or available than its preferred
prey.

Many years ago while skiing during a very harsh winter, i observed a pair of
Great H Owls that were roosting in a spruce grove being harassed by many Crows.
The Crows soon curtailed their harassing and headed towards their chosen
roosting site nearby for the night. As it became dark, I noticed both Owls fly
over to the Crows roosting site and actually observed an Owl take a crow from
it's horizontal perch and fly off with it!

It's a fact, when times get harsh, predators will often become more
opportunistic. If they do not, they might then pay the ultimate price. The best
example I know of an opportunistic predator species is the Red-tailed Hawk. They
will often change their preferences of prey to whatever is the most easily
available or abundant for them at the time. A list of prey species taken by
Redtails will show this fact.

And to answer the question of who is taking the chickens. In the many years i
have had Chickens, the only bird predator I ever had that attacked a chicken was
an Im Goshawk. This hawk tried to kill a full grown chicken for some time, till
I interrupted. The chicken soon died from the many talon piercings, but during
mid winter, I found the Gos dead near the outside coop in the snow. It had
apparently died from starvation. This is an example of a young predator that
just could not adapt to the harsh environment during its first winter. Nature
does cull out the weak and inexperienced during stressful times, but leaves the
successful to live on and propagate..............Paul Carrier
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