>Bob Mauritsen writes:
>
<snip>
>with the large numbers of rock doves,
>house sparrows, and starlings around, ( I wonder)
>why the populations of the
>appropriate raptor preditors haven't increased accordingly, so as
>to keep the numbers of skyrats, skymice, and skydodos down.

One of the limitations is appropriate nesting habitat, and some predators are
more adaptable than others. Peregrine Falcons have made themselves at home in
cities, to prey on rock doves, etc. because big buildings and bridges resemble
the cliff sites they prefer for nesting. Kestrels, on the other hand, take
advantage of highway margins to feed on the increased numbers of insects and
small mammals there but require Flicker holes in trees and the like for
nesting. Those sites are decreasing as older trees disappear. It's unlikely
we'll have a reclusive Northern Goshawk nesting in Seward Park anytime soon
even if Rock Doves are abundant, partly because a disease carried by Rock Doves
is fatal to Goshawks. So mere abundance of suitable prey is not enough to
sustain a population of a predator.

-------Herb Curl
>
>
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