Chesapeake Bay cormorants continue steep ascent -
http://www.ccbbirds.org/2013/12/03/chesapeake-bay-cormorants-continue-steep-ascent/
By Bryan Watts
On 23 May, 1978, while out conducting fieldwork, Charlie Blem (avian ecologist
from Virginia Commonwealth University) discovered 6 pairs of double-crested
cormorants nesting on the James River near Hopewell, Virginia. This was the
first documented breeding of the species within the Chesapeake Bay region. The
historic event was little noticed and there was no indication that in just over
3 decades the species would take root and become one of the dominant fish
consumers within the estuary. However, during the 2013 breeding season, a
survey conducted by The Center for Conservation Biology documented more than
5,000 pairs breeding in 12 colonies throughout the Chesapeake Bay. This
population would be expected to consume nearly 3000 metric tons of fish
annually.
Growth in the Chesapeake Bay breeding population has been both rapid and
dramatic. As recently as 1993, a survey conducted by the Center documented
only 354 pairs. During a visit in that year to Smith Island, Bryan Watts and
Mitchell Byrd discovered 6 nests built on top of old brown pelican nests. In
2013, this colony is the largest in the Bay supporting nearly 2,500 pairs.
Cormorants of several species are now considered nuisances within numerous
locations across the globe. In North America, populations were recovering from
widespread shooting during the 1940s and 1950s only to be reduced to new lows
by the 1960s due to the impacts of DDT. Since the banning of DDT, historic
populations have experienced dramatic recoveries leading to conflicts over the
destruction of habitat required by other bird species, nutrient inputs into
waterways, and fish consumption. Impacts of overwintering populations on the
aquaculture industry throughout the Southeast lead the Fish and Wildlife
Service to issue an aquaculture depredation order for 13 southern states in
1998. Conflicts with commercial and recreational fishing have led to the
ongoing control of northern breeding populations.
The Chesapeake Bay has always been a significant wintering site for northern
populations. For the decade prior to the discovery of breeding there was a
documented increase of cormorants using the Bay during winter. The current
size of the winter population is not known but believed to be substantial.
Northern birds that have not reached breeding age also oversummer in the Bay in
unknown numbers. The rise of the breeding population greatly increases the
fish demand during the summer period.
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
