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

SECOND NORTH AMERICAN SEA DUCK CONFERENCE
RESOURCE USE BY DIVING DUCKS DURING WINTER ON NORTHEASTERN LAKE
ONTARIO: A COMPARATIVE APPROACH TO UNDERSTANDING
CONTAMINANT ACQUISITION
Michael L. Schummer¹, Scott A. Petrie², and Robert C. Bailey³
¹Department of Biology, Long Point Waterfowl and Wetlands Research Fund & University of
Western Ontario, London, ON, Canada, N6A5B7; mschumme@uwo.ca
²Long Point Waterfowl and Wetlands Research Fund, Port Rowan, ON, Canada N0E 1M0
³Department of Biology, University of Western Ontario, London, ON, Canada, N6A 5B7
Populations of diving ducks using Lake Ontario during winter have increased since the 1980’s. This
could become problematic if ducks are acquiring unhealthy contaminant burdens by foraging on the
Great Lakes throughout winter. It was hypothesized that the increase in populations of diving ducks
was due to increased food resources after the introduction of dreissenid mussels (quagga [Dreissenia
bugensis] and zebra [D. polymorpha] mussels), who are relatively contaminated with selenium among
other metals of concern. Recently, numbers of diving ducks using Lake Ontario during winter have
stabilized, possibly indicating carry capacity during winter has been reached. However, little research
has been conducted on resource use and partitioning by diving ducks wintering at northern latitudes.
Therefore, wildlife managers have little idea of what, if anything, limits (or will limit) numbers of
diving ducks during winter on Lake Ontario. I investigated resource use and niche overlap, as well as
behavior, habitat use and body condition of diving ducks to determine if food availability was limiting
the number of birds using northeastern Lake Ontario during winter. Buffleheads (Bucephala albeola),
common goldeneyes (Bucephala clangula), and long-tailed ducks (Clangula hymelis) were studied
to elucidate complex interactions between variables and reduce the number of viable alternative
hypotheses. Results suggest that food is not a limiting resource to diving ducks using northeastern
Lake Ontario during winter. Therefore, more birds may winter within a location where their food
(dreissenid mussels) is relatively contaminated. However, while dreissenid mussels comprised
approximately 85% of the invertebrate community, they were consumed at relatively low levels by
birds. We are currently analyzing samples of macroinvertebrates and livers from various diving ducks
collected during winter on northeastern Lake Ontario to determine contaminant levels. By using three
species with different foraging habits and body size, we can assess whether or not and how birds are
acquiring contaminants during winter on Lake Ontario.
NOV. 7-11, 2005 ANNAPOLIS, MARYLAND, USA
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