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April 2013

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From:
Bill Whan <[log in to unmask]>
Reply To:
Bill Whan <[log in to unmask]>
Date:
Tue, 30 Apr 2013 15:38:10 -0400
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Today was the last day McKinley Ave would be open to through traffic for
a while, so Laura and I tried to estimate the numbers of nesting great
egrets, great blue herons, and double-crested cormorants visible from
the Shrum Mound; this is one of very few nesting sites away from Lake
Erie for the egrets and the cormorants, an isolated island in the middle
of a large quarry not far from the Scioto River.
        I've been wanting to find a vantage point to see the back of the island
from the west side, and after some wandering about on dirt roads we
stumbled upon the Liberty Horse Farm, a charming spot dedicated to
teaching city folk to interact with horses, a real ranch smack-dab in
the middle of urban industrial Columbus. The proprietors were very
hospitable, and allowed us to walk in pastures and parade grounds as we
looked for a point where the island was visible. I finally found a spot,
and counted 18 great egrets on the back side. We went over to the Mound,
and were able to end up with a count of ~50 great blue heron nests,
maybe as many as 40 cormorant nests, and perhaps 25 great egret nests.
These are estimates, since birds come and go all day long, and I tried
to count only incubating birds or those feeding young (many egrets had a
nestful already, some pretty big). I don't know if this might be the
largest great blue colony in the county, but it certainly is for the
egrets and cormorants, if not for the entire state away from Lake Erie.
        McKinley will not be open to "through traffic" for the next month;
maybe drivers will be able to get through to the Shrum Mound. Vegetation
will soon enough make many of the birds hard to see. The young local
egrets should start showing up along the river and in local marshes
sometime in May, I'd guess--quite early by historical standards.
        Only a few years ago, cliff swallows were ubiquitous here on
underpasses and bridges, and now many of those spots seem deserted. They
were estimated to nest under every bridge over the Scioto from here to
the Ohio River. Now they seem to have deserted many of these spots, and
one is led to wonder why.  One theory I've heard is that they
host obligate parasites that overwinter in old nest sites, leading to
increased mortality among the swallows, and that the birds have learned
to periodically abandon nest sites to control this. Has anyone else
noticed evidence of this? One more interesting fact that's come to light
recently: huge numbers of cliff swallows nest by choice under overpasses
along highways, especially out west. Understandably, they suffer a lot
from being hit by semis roaring by, and researchers have discovered that
this selection pressure has caused the wing-length of these swallows
measurably to decrease recently, giving them extra maneuverability to
avoid getting creamed by the traffic. Cool.
Bill Whan, Columbus


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