It was a sunny, Sunday afternoon, perfect for lolling about in the garden
and musing ecological questions....

Birds of prey, like all species, have an impact on the species around them.
When the population of Bald Eagles declined in the 60's and 70's, did the
populations of prey species change in response? For example, I heard of a
heon rookery that was decimated by predation by eagles last year. Did the
lower populations of eagles create an increase in Great Blue herons, since
there was probably less predation on the nests? I also heard of
significant eagle predation on nestling Murres on Tatoosh Island a few
seasons ago. So did Murres increased in the lower numbers of eagles? Will
Murres decrease under higher numbers of eagles?

If the eagles have recovered to their previous numbers, and in the
intervening time period habitat loss and other side effects of increasing
the human population has reduced populations of prey, would the eagle
population numbers be out of balance to their prey, even though their
numbers may have returned to what they used to be? Do endangered species
managers take this into account when making recovery plans?


Rob Sandelin
Naturalist, Writer
The Environmental Science School
http://www.nonprofitpages.com/nica/SVE.htm
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