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update on owl project



C-birders,

As many of you already know, I'm working on Barred Owl nesting ecology for
my Master's thesis project. This past season, we collected some nest site
selection and prey selection data. The nest site data consists of some
vegetation measurements and distances to roads, houses, and streams. Prey
selection data comes from pellets and prey remains found in nests and under
roosts. Currently, we are capturing owls and attaching radio transmitters in
a backpack configuration in order to collect home range and habitat use
information. At present, we have tagged 8 owls and profited from the
misfortune of one poor fellow who got himself stuck in a chimney. Capturing
owls is probably going to end up being the most "exciting" aspect of the
project. We use a taped broadcast of a hooting duet to locate nesting pairs.
After a few days of food provisioning (free live mice)to gain the trust of
the birds and get them temporarily conditioned to our presence to facilitate
capture, we use a bal chatri (falconry trap baited w/ white gerbil) to catch
them. This is a harmless method and the birds are immediately released
following attachment of the transmitter. 
We can't reach any concrete conclusions based on the preliminary information
we've gathered thus far, but some trends are certainly obvious. With respect
to prey selection, suburban owls seem to be feeding on passerine birds in
far greater proportion compared to their rural conspecifics. This may
explain the mobbing behavior I have commonly observed when calling in
suburban owls to the broadcast (I once was unfortunately under a "shower" of
small bird feces when an owl landed directly over my head). The rural guys
are primarily taking small rodents (voles, mice, chipmunks). It also appears
that suburban home ranges are considerably smaller than home range sizes
reported in the literature on northern populations, based on the locations
we've obtained while learning to use the telemetry equipment. It should be
interesting to observe the differences between suburban and rural birds as
we collect the serious telemetry data this spring.

Stay tuned!

Eric Harrold
Charlotte, NC