Friends: After several decades of watching populations of birds,
butterflies, and several other taxa, the thing I'm most impressed with
is how variable populations are. This is especially true among the
species with high reproductive potential (many insects, for example).
Still, there seems to be little doubt about the long term trend for bird
populations. Here's my only ref. on the subject:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Bird Population Changes in a Hamilton County, Ohio, Forest
LAUREN P. SAUNDERS, CHARLES W. SAUNDERS, DAVID STYER, AND STEPHAN
PELIKAN, Department of Mathematics, University of Cincinnati,
Cincinnati, OH 45221-0025
ABSTRACT. We monitored breeding bird populations in a woodland plot in
Hamilton County, OH. By comparing historical data (1991-8) with 2003
populations, we observed a decrease in the populations of more species
than expected by chance. In contrast, few species showed a population
increase. Overall, the total number of territorial males in 2003 was 12%
below the average number from 1991 to 1998. OHIO J SCI 105 (3):43-45, 2005
OHIO J SCI 105 (3):43-45, 2005
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Cheers!
Steve P
|