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During the period 1970-2000, substantial efforts were made to document the distribution and number of Trumpeter Swans (Cygnus buccinator) in western Canada. Breeding surveys have expanded from covering less than 20,000 km2 in the Grande Prairie region of Alberta to cover 780,000 km2, perhaps one-third of northwestern Canada. Aerial surveys involving total or partial counts have been used in most areas. Since 1995, sample-based surveys have been used in Yukon Territory and extreme northern British Columbia. Between 1970 and 2000, breeding surveys have documented a dramatic increase in both breeding distribution and numbers in western Canada (100 to more than 3,700). Winter surveys in British Columbia have corroborated...
Winters in interior Alaska (64°N) are characterized by short photoperiod (5L:19D) and chronic subfreezing temperatures. To determine if seasonal acclimatization of black‐capped chickadees (Poecile atricapilla) at high latitude differs from that of conspecifics at lower latitudes, standard metabolic rates (SMR), metabolic response to low temperature (−30°C), nocturnal hypothermia, body mass, fat reserves, and conductance were measured over two winters and one summer in three groups of seasonally acclimatized birds. Body mass and conductance did not vary with season, although furcular fat levels were higher in winter. Birds used nocturnal hypothermia when exposed to −30°C in summer or winter. Although SMR did not...
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I monitored the nesting area occupancy and reproductive success of Golden Eagles (Aquila chrysaetos) using data collected during two standardized aerial surveys in Denali National Park and Preserve (Denali) between 1988 and 2007. In 2007, occupancy of Golden Eagle nesting areas (91%), nesting rate (73%), and success rate (78%) were slightly higher than the long-term averages of those metrics. Fledging production (n = 72) was the second highest recorded in the study. During Golden Eagle surveys, I also collected data on the nesting area occupancy and reproductive success of Gyrfalcons (Falco rusticolus). In 2007, occupancy of Gyrfalcon nesting areas (46.7%) and success rate (42.8%) were lower than most previous years....
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Recent evidence suggests that mercury exposure has negative effects on the health of songbirds, and species that forage in wetlands may be at a greater risk of bioaccumulation of mercury than are those of other habitats. We examined mercury concentrations in blood and feathers from the wetland obligate and rapidly declining Rusty Blackbird (Euphagus carolinus) from five regions across North America: three wintering areas in the contiguous United States and breeding areas in the western boreal forests of Alaska and the Acadian forests of northeastern North America. In blood, mercury concentrations in Rusty Blackbirds from the Acadian forest (geometric mean 0.94 µg g-1; n = 59) were >3? than in those from Alaska (0.26...
The article presents a study which examines the total number of nesting Rusty Blackbirds (Euphagus carolinus) in boreal wetland habitats in Anchorage and Tanana Flats in Alaska. The study uses double sampling, and statistical analyses to estimate the number of pairs of nesting Rusty Blackbirds in Anchorage and Tanana Flats in 2007 and 2008. The result shows that habitat selection has been easily detected in Anchorage than Tanana Flats.
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Background Elucidating geographic locations from where migratory birds are recruited into adult breeding populations is a fundamental but largely elusive goal in conservation biology. This is especially true for species that breed in remote northern areas where field-based demographic assessments are logistically challenging. Methodology/Findings Here we used hydrogen isotopes (δD) to determine natal origins of migrating hatch-year lesser scaup (Aythya affinis) harvested by hunters in the United States from all North American flyways during the hunting seasons of 1999-2000 (n = 412) and 2000-2001 (n = 455). We combined geospatial, observational, and analytical data sources, including known scaup breeding range,...
Background Elucidating geographic locations from where migratory birds are recruited into adult breeding populations is a fundamental but largely elusive goal in conservation biology. This is especially true for species that breed in remote northern areas where field-based demographic assessments are logistically challenging. Methodology/Findings Here we used hydrogen isotopes (δD) to determine natal origins of migrating hatch-year lesser scaup (Aythya affinis) harvested by hunters in the United States from all North American flyways during the hunting seasons of 1999-2000 (n = 412) and 2000-2001 (n = 455). We combined geospatial, observational, and analytical data sources, including known scaup breeding range,...
The population genetic structure of northern boreal species has been strongly influenced both by the Quaternary glaciations and the presence of contemporary barriers, such as mountain ranges and rivers. We used a combination of mitochondrial DNA (mtDNA), nuclear microsatellites and spatial distribution modelling to study the population genetic structure of the boreal chickadee (Poecile hudsonicus), a resident passerine, and to investigate whether historical or contemporary barriers have influenced this northern species. MtDNA data showed evidence of eastern and western groups, with secondary admixture occurring in central Canada. This suggests that the boreal chickadee probably persisted in multiple glacial refugia,...
A program to control wolves (Canis lupus) in interior Alaska in 1993 and 1994 did not result in expected increases in calf survival in the Delta caribou (Rangifer tarandus) herd (DCH). Therefore, the Alaska Department of Fish and Game conducted a study to determine causes of calf mortality during 1995-1997 and monitored recruitment, mortality, and population size annually in the DCH for 6 years after wolf control ended. Despite removal of 60-62% of the autumn 1993 wolf population, wolves still killed 25% of 166 radiocollared calves between birth in mid- to late May and 30 September during 1995-1997. Although autumn calf:cow ratios in the DCH increased after wolf control, similar increases in calf:cow ratios occurred...
We examined long-term databases concerning population status of scaup (lesser [Aythya affinis] and greater scaup [A. marila] combined) and harvest statistics of lesser scaup to identify factors potentially limiting population growth. Specifically, we explored evidence for and against the general hypotheses that scaup populations have declined in association with declining recruitment and/or female survival. We examined geographic heterogeneity in scaup demographic patterns that could yield evidence about potential limiting factors. Several biases exist in survey methodology used to estimate scaup populations and harvest statistics; however, none of these biases likely accounted for our major findings that (1) the...
During the period 1970-2000, substantial efforts were made to document the distribution and number of Trumpeter Swans (Cygnus buccinator) in western Canada. Breeding surveys have expanded from covering less than 20,000 km2 in the Grande Prairie region of Alberta to cover 780,000 km2, perhaps one-third of northwestern Canada. Aerial surveys involving total or partial counts have been used in most areas. Since 1995, sample-based surveys have been used in Yukon Territory and extreme northern British Columbia. Between 1970 and 2000, breeding surveys have documented a dramatic increase in both breeding distribution and numbers in western Canada (100 to more than 3,700). Winter surveys in British Columbia have corroborated...
map background search result map search result map Species richness and distributions of boreal waterbird broods in relation to nesting and brood-rearing habitats Lesser Scaup Nest Success and Duckling Survival on the Yukon Flats, Alaska Trumpeter Swan Numbers and Distribution in Western Canada, 1970-2000 Lesser scaup nesting ecology in relation to water chemistry and macroinvertebrates on the Yukon Flats, Alaska Dynamic multistate site occupancy models to evaluate hypotheses relevant to conservation of Golden Eagles in Denali National Park, Alaska Monitoring Occupancy of Nesting Areas and Reproductive Success of Golden Eagles in Denali National Park and Preserve, Alaska Dynamic multistate site occupancy models to evaluate hypotheses relevant to conservation of Golden Eagles in Denali National Park, Alaska Monitoring Occupancy of Nesting Areas and Reproductive Success of Golden Eagles in Denali National Park and Preserve, Alaska Species richness and distributions of boreal waterbird broods in relation to nesting and brood-rearing habitats Lesser scaup nesting ecology in relation to water chemistry and macroinvertebrates on the Yukon Flats, Alaska Lesser Scaup Nest Success and Duckling Survival on the Yukon Flats, Alaska Trumpeter Swan Numbers and Distribution in Western Canada, 1970-2000