Great Blue Herons Rebound in the Chesapeake Bay
see full story and map here:
http://www.ccbbirds.org/2013/09/23/great-blue-herons-rebound-in-the-chesapeake-bay/
By Bryan Watts
Breeding populations of great blue herons have made a dramatic comeback within
the Chesapeake Bay according to a 2013 survey conducted by The Center for
Conservation Biology. As with bald eagles and osprey, great blue heron
populations suffered deep declines during the DDT era reaching a low in the
late 1960s of approximately a dozen known breeding colonies. The 2013 survey
documented 14,126 pairs within 407 breeding colonies making the species the
most widespread and abundant breeding waterbird in the Chesapeake Bay. The
population would consume an estimated 8 metric tons of fish annually. Colonies
were documented within every county along the tidal reach of the estuary.
An interesting finding of the survey is that the size of breeding colonies has
been declining for more than a decade. The average colony size in 2013 was 35
pairs compared to more than 110 pairs in 1985. Large colonies that were stable
for decades have begun to splinter and scatter across the landscape. Although
the underlying cause of the decline remains unclear, one possible contributing
factor may be the recovery of bald eagles. Bald eagles now nest in a growing
number of heron colonies. The largest colony in the Bay on Pooles Island
(1,450 pairs) now contains 4 bald eagle nests and the second largest colony on
Mason Neck (1,250 pairs) now contains 2 eagle nests.
In addition to great blue herons, the survey also included great egrets. More
associated with coastal waters and never as common as great blue herons in the
Chesapeake Bay, 1,775 egret pairs were found in 39 colonies. This number
represents a nearly 3 fold increase in the population over the past 30 years.
The 2013 aerial survey conducted by Bryan Watts and Bart Paxton required 200
hours of flying and covered more than 900 tidal tributaries of the Chesapeake.
Funding for the survey was provided by the Virginia Department of Game & Inland
Fisheries, the Maryland Department of Natural Resources, and The Center for
Conservation Biology. The Center for Conservation Biology is a research unit
within the College of William and Mary and the Virginia Commonwealth University.
Michael Wilson
Center for Conservation Biology
College of William and Mary & Virginia Commonwealth University
P.O. Box 8795
Williamsburg, VA 23187-8795
phone: 757-221-1649
fax: 757-221-1650
email: mdwils@xxxxxx
web: www.ccbbirds.org
