Subject: Re: Eagles and Heron Nesting Disturbance?
Date: Jun 4 14:49:59 1996
From: Don Baccus - donb at Rational.COM


>Maureen, from what I've been able to glean, eagles are the *primary* cause
>for heronry failure in this area, probably much more significant than human
>disturbance. As Bald Eagles have recovered from earlier declines, they are
>increasing throughout the region, and a consequence of this might well be
>greater and greater problems with heronries. Apparently both small and
>large ones can be sufficiently disturbed by eagle presence to fail.

Interesting. Ross Island, home to the largest heronry in Portland,
has a brand-new feature this year: a bald eagle nest. First bald
eagle nest on the Portland Willamette that I can remember, it must
be decades since the last one.

What does a good conservationist do when the National Emblem begins
munching Portland's official City Bird - especially during Great
Blue Heron Week (this week, as a matter of fact)? :) :)

ODF&W monitors productivity of this heronry so some hard data
should become available as the years go by...

Since bald eagles are highly territorial during the breeding
season, only one pair is likely to ever include a particular heronry
in their territory. So, the effect is likely going to depend on
the size of the heronry.

I wonder if herons ever mob a maurading eagle? That would be a sight
to see!


- Don Baccus, Portland OR <donb at rational.com>
Nature photos, on-line guides, at http:://www.xxxpdx.com/~dhogaza