The costs of escalated territorial defence have not been well-documented, although in theoretical... more The costs of escalated territorial defence have not been well-documented, although in theoretical studies they are often assumed to be high. We manipulated territorial defence in red squirrels (Tamiasciurus hudsonicus) to assess the costs of territorial disputes in terms of energy, reproductive status, and predation. Feeders containing sunflower seeds were used to manipulate foraging behaviour and induce territorial disputes. Experimental squirrels displayed dramatically higher rates of territorial behaviours in response to feeders, and while there was no difference in survival between experimental and control squirrels, in 4 of the 17 disputes territory owners lost their territories. All 3 females that did so suffered reproductive costs. Territorial disputes were won by the heavier squirrels in all 12 cases where contestants were of different masses, but where the contestants were of similar masses (4 of 5 cases), territory owners were more likely to win.
We examined the extent and impact of predation on red squirrels (Tamiasciurus hudsonicus) during ... more We examined the extent and impact of predation on red squirrels (Tamiasciurus hudsonicus) during a cyclic decline of snowshoe hares in the southwestern Yukon, Canada. We monitored survival of squirrels on three control grids and a predator exclosure from March 1991 through August 1993. On controls, adult survival during the breeding season decreased from 1991, when snowshoe hare populations were high, to 1992, when hare populations declined rapidly. Survival increased slightly in 1993, when hare and predator populations were very low. Similarly, adult survival during winter was lower in 1992 – 1993 than in 1991 – 1992. Adult survival on the exclosure remained similar in each breeding season but declined during winter 1992 – 1993. Adult survival was similar on the controls and the exclosure in each year except during winter 1991–1992 and the 1992 breeding season, when it was lower on the controls. There was no difference in juvenile survival between the controls and the exclosure. Despite the decrease in adult survival due to predation, there was no population decline on any of the control grids. We conclude that predation did not have a measurable impact on red squirrel densities at Kluane and that it is unlikely red squirrels show 10-year population cycles in conjunction with snowshoe hares.
Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radi... more Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radiocollared and monitored across 20,000 km2 of northeastern Alberta. Adult survival averaged 0.88 + 0.03, and did not differ among years. Calf survival was 18 calves/100 cows in ...
... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Departme... more ... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Department of Forest Science, Forestry Sciences Lab 020, Oregon State University, Corvallis, OR 97331, USA. wolves is often cited as ...
... I surveyed songbirds in 176 stands in the Rocky Mountains of southeastern British Columbia, C... more ... I surveyed songbirds in 176 stands in the Rocky Mountains of southeastern British Columbia, Canada, that had been ... Page 4. SONGBIRD COMMUNITIES IN BURNED AND LOGGED STANDS WITH VARIABLE TREE RETENTION IN THE CANADIAN ROCKY MOUNTAmjS ...
Behavioural differences between surviving and depredated juvenile red squirrels. AK Stuart-Smith,... more Behavioural differences between surviving and depredated juvenile red squirrels. AK Stuart-Smith, S Boutin Ecoscience. ... Adult red squirrels spent significantly less time in exposed places than juveniles, which may relate to the lower depredation rates experienced by adults. ...
ABSTRACT ABSTRACT The northern goshawk (Accipiter gentilis) has been the subject of considerable ... more ABSTRACT ABSTRACT The northern goshawk (Accipiter gentilis) has been the subject of considerable interest because of the impact of logging on this species' nesting habitat. However, few studies have examined movements of fledgling birds around the nest prior to independence, and even fewer have described resource requirements of young birds during their postfledging period. Over 3 years, we followed 31 radiotagged goshawk fledglings from 15 nests in southeastern British Columbia, Canada. Of these birds, 26 survived to disperse. Between fledging and dispersal 95% of fledgling relocations (n = 1, 148) were within 450 m of the nest. Fledglings primarily remained within 298 m of the nest during the first 21 days postfledging and within 525 m of the nest between 21 days postfledging and dispersal. Fledglings' movements were highly directional, with individual and sibling movements away from any particular nest tending out in one direction. Postfledging areas averaged 36.7 ha in size (median = 23.1, inter-quartile range = 20.8–39.7 ha). Fledglings strongly avoided forest <40 years old and weakly selected young forests (40–80 yr), mature forests (>80 yr), and stands with >40% canopy cover during the first 21 days and after. We suggest forest managers wishing to conserve goshawk postfledging areas in the interior montane forests of British Columbia maintain forests >40 years old with high crown closure covering an area ≥21 ha and preferably >40 ha. This area should contain all identified occupied and alternative nest trees in a nest area. At least half this area should be forest >80 years old and contain existing nests and potential for future nest trees.
Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radi... more Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radiocollared and monitored across 20,000 km2 of northeastern Alberta. Adult survival averaged 0.88 + 0.03, and did not differ among years. Calf survival was 18 calves/100 cows in ...
... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Departme... more ... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Department of Forest Science, Forestry Sciences Lab 020, Oregon State University, Corvallis, OR 97331, USA. wolves is often cited as ...
The costs of escalated territorial defence have not been well-documented, although in theoretical... more The costs of escalated territorial defence have not been well-documented, although in theoretical studies they are often assumed to be high. We manipulated territorial defence in red squirrels (Tamiasciurus hudsonicus) to assess the costs of territorial disputes in terms of energy, reproductive status, and predation. Feeders containing sunflower seeds were used to manipulate foraging behaviour and induce territorial disputes. Experimental squirrels displayed dramatically higher rates of territorial behaviours in response to feeders, and while there was no difference in survival between experimental and control squirrels, in 4 of the 17 disputes territory owners lost their territories. All 3 females that did so suffered reproductive costs. Territorial disputes were won by the heavier squirrels in all 12 cases where contestants were of different masses, but where the contestants were of similar masses (4 of 5 cases), territory owners were more likely to win.
We examined the extent and impact of predation on red squirrels (Tamiasciurus hudsonicus) during ... more We examined the extent and impact of predation on red squirrels (Tamiasciurus hudsonicus) during a cyclic decline of snowshoe hares in the southwestern Yukon, Canada. We monitored survival of squirrels on three control grids and a predator exclosure from March 1991 through August 1993. On controls, adult survival during the breeding season decreased from 1991, when snowshoe hare populations were high, to 1992, when hare populations declined rapidly. Survival increased slightly in 1993, when hare and predator populations were very low. Similarly, adult survival during winter was lower in 1992 – 1993 than in 1991 – 1992. Adult survival on the exclosure remained similar in each breeding season but declined during winter 1992 – 1993. Adult survival was similar on the controls and the exclosure in each year except during winter 1991–1992 and the 1992 breeding season, when it was lower on the controls. There was no difference in juvenile survival between the controls and the exclosure. Despite the decrease in adult survival due to predation, there was no population decline on any of the control grids. We conclude that predation did not have a measurable impact on red squirrel densities at Kluane and that it is unlikely red squirrels show 10-year population cycles in conjunction with snowshoe hares.
Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radi... more Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radiocollared and monitored across 20,000 km2 of northeastern Alberta. Adult survival averaged 0.88 + 0.03, and did not differ among years. Calf survival was 18 calves/100 cows in ...
... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Departme... more ... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Department of Forest Science, Forestry Sciences Lab 020, Oregon State University, Corvallis, OR 97331, USA. wolves is often cited as ...
... I surveyed songbirds in 176 stands in the Rocky Mountains of southeastern British Columbia, C... more ... I surveyed songbirds in 176 stands in the Rocky Mountains of southeastern British Columbia, Canada, that had been ... Page 4. SONGBIRD COMMUNITIES IN BURNED AND LOGGED STANDS WITH VARIABLE TREE RETENTION IN THE CANADIAN ROCKY MOUNTAmjS ...
Behavioural differences between surviving and depredated juvenile red squirrels. AK Stuart-Smith,... more Behavioural differences between surviving and depredated juvenile red squirrels. AK Stuart-Smith, S Boutin Ecoscience. ... Adult red squirrels spent significantly less time in exposed places than juveniles, which may relate to the lower depredation rates experienced by adults. ...
ABSTRACT ABSTRACT The northern goshawk (Accipiter gentilis) has been the subject of considerable ... more ABSTRACT ABSTRACT The northern goshawk (Accipiter gentilis) has been the subject of considerable interest because of the impact of logging on this species' nesting habitat. However, few studies have examined movements of fledgling birds around the nest prior to independence, and even fewer have described resource requirements of young birds during their postfledging period. Over 3 years, we followed 31 radiotagged goshawk fledglings from 15 nests in southeastern British Columbia, Canada. Of these birds, 26 survived to disperse. Between fledging and dispersal 95% of fledgling relocations (n = 1, 148) were within 450 m of the nest. Fledglings primarily remained within 298 m of the nest during the first 21 days postfledging and within 525 m of the nest between 21 days postfledging and dispersal. Fledglings' movements were highly directional, with individual and sibling movements away from any particular nest tending out in one direction. Postfledging areas averaged 36.7 ha in size (median = 23.1, inter-quartile range = 20.8–39.7 ha). Fledglings strongly avoided forest <40 years old and weakly selected young forests (40–80 yr), mature forests (>80 yr), and stands with >40% canopy cover during the first 21 days and after. We suggest forest managers wishing to conserve goshawk postfledging areas in the interior montane forests of British Columbia maintain forests >40 years old with high crown closure covering an area ≥21 ha and preferably >40 ha. This area should contain all identified occupied and alternative nest trees in a nest area. At least half this area should be forest >80 years old and contain existing nests and potential for future nest trees.
Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radi... more Abstract: From 1991 through 1994, 65 adult woodland caribou (Rangifer tarandus caribou) were radiocollared and monitored across 20,000 km2 of northeastern Alberta. Adult survival averaged 0.88 + 0.03, and did not differ among years. Calf survival was 18 calves/100 cows in ...
... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Departme... more ... Grande Prairie, AB T8V 6J4, Canada. 2 E-mail:adam.james@gov.ab.ca 3 Present address: Department of Forest Science, Forestry Sciences Lab 020, Oregon State University, Corvallis, OR 97331, USA. wolves is often cited as ...
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