abstracts of oral and poster presentations - Pacific Seabird Group

for only 4% of the total adult female population at a scale of approximately 100 km 2 . We conclude that
wintering Harlequin Duck populations are demographically structured at relatively small scales, which has
important implications for the scale of conservation action for the species.
CONSERVATION ASSESSMENT OF BREEDING WESTERN AND CLARK'S GREBES IN NORTHERN
CALIFORNIA
Gary L. Ivey (ivey@oregonvos.net); Corvallis, OR USA
Although the population status of Aechmophorus grebe species is uncertain, there is evidence of a
declining trend. I conducted an assessment of the status and conservation needs of breeding Aechmophorus
grebes at a number of important sites in California in 2003. At these sites, nesting grebes face a number of
issues that reduce their productivity, including disturbance at breeding colonies, problems with boat wakes and
wind, poor habitat conditions, and water-level changes. Issues to address vary by location but generally include
the need to post nesting-colony sites as closed areas to prevent disturbance during the nesting season, maintain
stable water levels as much as possible, provide outreach to the public about grebes, post no-wake zones (and in
some cases, install wave barriers to protect nests from waves), restore nesting habitat where possible, and
monitor the results of implemented management actions. I recommend a regional approach to grebe
conservation, including coordinated monitoring and decision-making processes.
INFLUENCES ON SURVIVAL OF GREATER SANDHILL CRANE NESTS AT MALHEUR NATIONAL
WILDLIFE REFUGE, HARNEY COUNTY, OREGON
Gary L. Ivey* 1 (ivey@oregonvos.net) and Bruce D. Dugger 2 ; 1 Corvallis, OR USA; 2 Department of Fisheries
and Wildlife, Oregon State University, Corvallis, OR USA
Malheur National Wildlife Refuge is among the most important breeding sites for Greater Sandhill
Cranes (Grus canadensis tabida) in the western US. We collected a large sample of data from crane nests here
from 1990–1998 and used logistic regression to evaluate the effects of land use, predator abundance, weather
factors, nest-site habitat, nest initiation timing, and intra-specific interactions (pair-density) on Greater Sandhill
Crane nest survival. The results of our study identify important factors to consider in the management of
wildlife areas to enhance productivity of Sandhill Cranes.
ASSESSMENT OF SANDHILL CRANE ECOLOGY IN THE SACRAMENTO-SAN JOAQUIN DELTA,
CALIFORNIA, 2002–2003
Gary L Ivey 1 (ivey@oregonvos.net) and Caroline P. Herziger 2 ; 1 Corvallis, OR USA; 2 Blaine, WA USA
A study of wintering Sandhill Crane (Grus canadensis) ecology was conducted in 2002–2003 in the
Sacramento–San Joaquin Delta, with Staten Island (Staten) being the focus, and was conducted to address the
problem of defining conservation needs for cranes, including the state-threatened Greater subspecies (G. c.
tabida). Staten supported approximately 15% of the Greater’s population, and 36% of all crane foraging use in
the Delta through the entire winter. Use of crops shifted in response to availability, with high preference for
wheat, while corn was the most important crop through the entire winter. Winter home ranges of Greaters
averaged less than one square mile. Flight distances from roost sites to foraging areas also averaged less than
one mile. In contrast, Lesser Sandhill Cranes (G. c. canadensis) had much larger winter ranges and foraged
farther from roost sites. Traditional crane wintering areas such as the Delta are vital to the welfare of cranes.
Staten has increased in importance, while habitat loss continues to occur at other sites. Further decline of crane
habitat could result in population-level effects, and, because relevant findings in our study indicate small winter
home ranges and strong site fidelity, very local habitat mitigation would be necessary to minimize these impacts.
IT’S THE FAT! [Poster]
Shoshanah R. Jacobs* 1 (sjaco096@uottawa.ca), Anthony Gaston 2 , and Jean-Michel Weber 3 ; 1 Department of
Biology, University of Ottawa, ON CANADA; 2 Canadian Wildlife Service, Carleton University, Ottawa, ON
CANADA; 3 University of Ottawa, Department of Biology, Ottawa, ON CANADA
Birds vary their mass during breeding to optimise the cost of transport and in response to energy reserve
needs for incubation and other activities. Most energy reserves consist of lipids. Though it has been widely