Subject: peregrines and windows
Date: Sep 10 14:57:01 1994
From: "WHITLOCK. PETER L." - WHIT0522 at VARNEY.IDBSU.EDU


The recent questions about peregrines hitting windows remind me of a
few conversations I have had with various raptor biologists in the
last few years. Dr. Tom French of Massachusetts Fish & Wildlife is
one of the most vocal people I have seen speaking in support of
reintroducing peregrines in cities. I've seen him show graphs with
return rates for peregrines reintroduced in cities and with those
released at historic cliff sites. If I remember correctly, the
difference was that almost three
times as many birds tend to return to a site somewhere in the
state if they were reintroduced in a city rather than on a cliff.
That was gathered from birds over more than 15 years in various
eastern states. Band recoveries sometimes seem to suggest that
survivorship is higher among city birds; this seems esp. strange
given that one is more likely to recover the bird in a city. The
reason most frequently suggested is that food is much more available
in cities. I suspect there is also an effect with birds becoming
more easily habituated to human activity. Cliff sites are becoming
increasingly prone to disturbance, and thus
nesting at these sites may be risky. But birds in the city with no
fear may have an easier time.
Dr. Dan Varland recently published a paper about a kestrel nest
box program along interstates in Indiana. As a rehabilitator a few
years ago, I was all too familiar with kestrels hit by cars, and
Dan's paper made me ask what in the hell he was thinking of. But he
said kestrel productivity in these boxes was quite high, and road
mortality from roadside nest boxes was not high enough that it was a
great concern. It seems strange to me, just as Dennis Paulson's
concerns made the Seattle peregrine situation seem a bit strange.
It's necessary to remember that mortality is high among raptors.
Perhaps they are learning to coexist with humanity much better than
it would seem when you are staring a dead or injured bird in the
face. And perhaps what cityfying these birds has done is bring their
deaths out into the open where we can see them. That does not
necessarily mean a larger number are dying.
Dan Klem of York University is the first name that comes to mind
for studying window kills, but he hasn't done a study of raptors that
I know of. There is some info in Ian Newton's _Population Ecology of
Raptors_; I'll check if there's anything esp. relevant.
The Raptor Research Foundation held a special symp. on raptor
coexistence with people at their last annual mtg. in Charlotte, NC.
Harriers hunting around mine tailings, a guy from Barlow U. who
suggested that screech owl productivity is higher in suburban than in
rural areas (but his definition of rural was flawed, mostly farmland
rather than wilderness), etc. I'll check the abstracts from that too.

Peter Whitlock
Boise State University