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

SECOND NORTH AMERICAN SEA DUCK CONFERENCE
FORAGING ECOLOGY AND BODY COMPOSITION
OF STARVING COMMON EIDERS
DURING A WINTER DIE-OFF EVENT IN ARCTIC CANADA
Sarah Jamieson¹ and Grant Gilchrist²
¹Simon Fraser University; 8888 University Dr., Burnaby, British Columbia, V5A 1S6, Canada;
sjamieso@sfu.ca
²Canadian Wildlife Service, 1125 Colonel By Drive, Raven Road, Carleton University, Ottawa,
Canada. K1A 0H3 J
Winter is often an energetically stressful time of year, and birds living at high latitudes tend to either
migrate or store fat reserves to avoid starvation. Occasionally, birds that remain in Arctic environments
in winter are unable to meet their energetic requirements, and if poor conditions persist beyond their
energetic reserves, large numbers can die simultaneously. We observed common eiders (Somateria
mollissima sedentaria) starving to death in an ice-floe edge habitat off the Belcher Islands, Nunavut,
Canada in February, 2003. Upon our arrival, 430 eiders were present in three small open water areas
(1-3 ha within 800m of each other), with an average depth of 23 m, in a marine environment that was
otherwise completely covered in sea ice. Over 10 days, the open water areas gradually froze over
due to extreme cold (-30C), no wind, and weak tides. Despite intense foraging activity and ingestion
of benthic prey, all eiders eventually starved to death. During this period, we collected the intact
carcasses of starved eiders within 3 hrs of their death, and also a sample of live birds. Their carcass
composition was compared to healthy eiders collected in previous years at the same location and time
of year. In previous years, the average body mass of eiders was approximately 2300g whereas the
body mass of eiders collected dead in 2003 was approximately1400g. All carcass components that
were compared (including total protein, total lipid, total mineral, heart, gizzard, kidney, liver, spleen,
large and small intestine, leg muscle, leg bone, abdominal fat, and leg fat) were significantly lower in
starved birds, with the only exception being leg bone mass. Birds that were collected in the process
of starving showed steep declines in lipid stores, and initial signs of protein metabolism and organ
catabolism. Interestingly however, there was evidence that gizzard mass increased as eiders starved.
These data are among the first to quantify the starvation threshold of waterfowl dying naturally in the
wild, as well as rates of physiological change such as organ catabolism apparently invoked to avoid
death.
56 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005