Subject: vulture habits; was: Turkey Vulture migration
Date: Oct 2 11:19:35 1996
From: Dennis Paulson - dpaulson at mirrors.ups.edu


Jack Bowling wrote:

>On the general question of available habitat for TUVU in BC, habitat is
>only one part of the equation: they need a food supply, also. If we assume
>that our road and highway system and the constant roadkills will always
>take care of that need for TUVU, then appropriate habitat does become the
>main limiter. A few things can be linked here: 1) forests are being cleared
>at a fairly constant rate; 2) numbers of large ungulates such as moose
>which move into the clearcuts and road allowances have been increasing over
>the past 30 years or so as the forests opened up; 3) road and rail kills of
>large ungulates have been increasing in lockstep with the increasing
>population; (etc.)

I myself have never seen a Turkey Vulture at a road kill in Washington,
although I've seen it innumerable times in other parts of the U.S. and
throughout the tropics. I've seen more Golden Eagles at road kills than
TUVUs in this state, and ravens are of course our preeminant avian
scavengers, followed by crows. This isn't true in the South, where far
more vultures than corvids are seen at road kills. But Turkey Vultures are
often at small carcasses, whereas Black Vultures tend to be more common at
large carcasses.

And I haven't been terribly surprised at not seeing them. Turkey Vultures
find their prey by smell, so in theory they should be able to find any dead
animal of any size (down to mouse, I suppose) *away* from roads. No matter
the carnage on the roads, there are still *far more* dead animals away from
them. The great majority of small birds and mammals born this summer will
be dead by next summer, not to mention large numbers of large birds and
mammals. I do realize that predators take a very large percentage of them,
but I suspect there are a lot of creatures that die of sickness,
starvation, old age and the like that could feed the vulture populations
quite adequately. And of course I agree that dead animals on roads are
likely to do this too, but I don't think it's particularly common here.
I've driven past a very large number of dead animals of all sizes in areas
where vultures occurred without seeing any at the carcasses.

I guess my final evidence for this hypothesis is that all over the world,
vultures are common even where there are no roads.

Dennis Paulson, Director phone 206-756-3798
Slater Museum of Natural History fax 206-756-3352
University of Puget Sound e-mail dpaulson at ups.edu
Tacoma, WA 98416