Second North American Sea Duck Conference - Patuxent Wildlife ...

SECOND NORTH AMERICAN SEA DUCK CONFERENCE
THE EFFECT OF VARYING PROTEIN LEVELS ON BLOOD CHEMISTRY, FOOD
CONSUMPTION, AND BEHAVIOR OF CAPTIVE SEADUCKS
Alicia M. Wells-Berlin, Matthew C. Perry, and Glenn H. Olsen
USGS Patuxent Wildlife Research Center, 12100 Beech Forest Road, Laurel, MD 20708 USA;
awells@usgs.gov
The Chesapeake Bay is a primary wintering area for scoters and the long-tailed ducks (Clangia
hyemalis) that migrate along the Atlantic Flyway. Recently, the Chesapeake Bay had undergone
an ecosystem shift and little is known about how this is affecting the seaduck populations. We
are determining what are the preferred food sources of the seaducks wintering on the Bay and
analyzing the factors influencing prey selection whether it is prey composition, energy assimilated,
prey availability, or a combination of any or all of these factors. We have established a captive
colony of surf (Melanitta perspicillata) and white-winged scoters (Melanitta fusca) as well as longtailed
ducks at Patuxent Wildlife Research Center to allow us to examine these factors in a more
controlled environment. This project contains a multitude of experiments and the resultant data will
be compiled into a compartmental model on the feeding ecology of seaducks wintering on the Bay.
The first experiment entailed feeding groups of each species (four ducks per pen of equal sex ratio,
if possible, and four pens per species) three diets varying in percent protein levels from November
to February. Each diet was randomly assigned to each pen and the amount of food consumed was
recorded each day. New feed was given when all existing food was consumed. Behavioral trials and
blood profiles were completed on all study birds to determine the effects of the varying diets. There
were no significant differences in food consumption, blood chemistry, and behavior detected at the
5% level among the diets for all three species of interest. There was a seasonal effect determined
based on the food consumption data for white-winged scoters, but not for surf scoters or long-tailed
ducks. The blood profiles of the surf scoters were compared to blood profiles of wild surf scoters and
a there was no difference detected at the 5% level. As a health check of the ducks an aspergillosis
test was run on the blood obtained during the experiment and it was found that surf scoters are more
resistant to the disease than the other species. In the next two winters natural prey items available
to seaducks wintering in the Chesapeake Bay will be offered on palettes to examine preference
without the additional energetic costs of diving. Assimilation efficiency trials will be run on all three
species to determine amount of energy the ducks obtain from each food source. Finally, using two
large aquariums, prey preference will be analyzed with the additional energetic costs of diving and
searching for prey. In addition, we will determine the effect of availability of a prey item on the prey
selection of seaducks. We hope the model created from these experiments will allow managers to
examine the effects of changes in the benthos on the seaduck populations wintering in the Chesapeake
Bay.
NOV. 7-11, 2005 ANNAPOLIS, MARYLAND, USA
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