Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle

I examined food and predation as factors limiting arctic ground squirrel (Spermophilus parryii plesius) populations during the decline and low phases of a snowshoe hare cycle (1992 - 1995). Food and predator limitation were tested experimentally with large-scale (36-ha) experimental manipulations: t...

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Main Author: Byrom, Andrea Elizabeth
Format: Thesis
Language:English
Published: 1997
Subjects:
Online Access:http://hdl.handle.net/2429/7269
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spelling ftunivbritcolcir:oai:circle.library.ubc.ca:2429/7269 2023-05-15T14:31:28+02:00 Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle Byrom, Andrea Elizabeth 1997 7280082 bytes application/pdf http://hdl.handle.net/2429/7269 eng eng For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. Text Thesis/Dissertation 1997 ftunivbritcolcir 2019-10-15T17:46:52Z I examined food and predation as factors limiting arctic ground squirrel (Spermophilus parryii plesius) populations during the decline and low phases of a snowshoe hare cycle (1992 - 1995). Food and predator limitation were tested experimentally with large-scale (36-ha) experimental manipulations: two food-supplemented areas, a predator exclosure, and a food-supplemented treatment where predators were also excluded. Predator removal doubled population density, while addition of food resulted in a four-fold density increase. Removal of predators and addition of food together resulted in a 10-fold increase in arctic ground squirrel population densities. Population densities and adult survival rates were lower in 1992 and 1993 (two years after the snowshoe hare population decline) than in 1994 and 1995. Food supply and predation interact to limit arctic ground squirrel population densities in the boreal forest during the decline and low phases of the snowshoe hare cycle. Supplemental food did not affect dispersal distances or dispersal frequency of 172 radio-collared juveniles of either sex in any year. Juveniles that moved farther from their natal burrow were more likely to die. Males moved farther than females and died more frequently. Dispersal tendency was unrelated to population density in males. Females increased their tendency to disperse only on a study site with population densities 17x those of control populations. Male arctic ground squirrels probably disperse to avoid inbreeding, while females may disperse in response to resource limitation at very high densities. Philopatric females had higher fitness than females that dispersed, particularly if survival during dispersal was taken into account. As population density increased from 1992 - 1995, home range overlap of adult females also increased, as daughters survived to reproductive age in contact with their mother's home range. A stage-based simulation model of the annual cycle of activity and hibernation in arctic ground squirrels was strongly sensitive to adult and juvenile female survival. Arctic ground squirrel populations in the boreal forest can sustain a positive rate of population increase during the low phase of the snowshoe hare cycle, facilitated by flexibility of adult female home range overlap and high adult female survival. Science, Faculty of Zoology, Department of Graduate Thesis Arctic ground squirrel Arctic University of British Columbia: cIRcle - UBC's Information Repository Arctic
institution Open Polar
collection University of British Columbia: cIRcle - UBC's Information Repository
op_collection_id ftunivbritcolcir
language English
description I examined food and predation as factors limiting arctic ground squirrel (Spermophilus parryii plesius) populations during the decline and low phases of a snowshoe hare cycle (1992 - 1995). Food and predator limitation were tested experimentally with large-scale (36-ha) experimental manipulations: two food-supplemented areas, a predator exclosure, and a food-supplemented treatment where predators were also excluded. Predator removal doubled population density, while addition of food resulted in a four-fold density increase. Removal of predators and addition of food together resulted in a 10-fold increase in arctic ground squirrel population densities. Population densities and adult survival rates were lower in 1992 and 1993 (two years after the snowshoe hare population decline) than in 1994 and 1995. Food supply and predation interact to limit arctic ground squirrel population densities in the boreal forest during the decline and low phases of the snowshoe hare cycle. Supplemental food did not affect dispersal distances or dispersal frequency of 172 radio-collared juveniles of either sex in any year. Juveniles that moved farther from their natal burrow were more likely to die. Males moved farther than females and died more frequently. Dispersal tendency was unrelated to population density in males. Females increased their tendency to disperse only on a study site with population densities 17x those of control populations. Male arctic ground squirrels probably disperse to avoid inbreeding, while females may disperse in response to resource limitation at very high densities. Philopatric females had higher fitness than females that dispersed, particularly if survival during dispersal was taken into account. As population density increased from 1992 - 1995, home range overlap of adult females also increased, as daughters survived to reproductive age in contact with their mother's home range. A stage-based simulation model of the annual cycle of activity and hibernation in arctic ground squirrels was strongly sensitive to adult and juvenile female survival. Arctic ground squirrel populations in the boreal forest can sustain a positive rate of population increase during the low phase of the snowshoe hare cycle, facilitated by flexibility of adult female home range overlap and high adult female survival. Science, Faculty of Zoology, Department of Graduate
format Thesis
author Byrom, Andrea Elizabeth
spellingShingle Byrom, Andrea Elizabeth
Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle
author_facet Byrom, Andrea Elizabeth
author_sort Byrom, Andrea Elizabeth
title Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle
title_short Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle
title_full Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle
title_fullStr Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle
title_full_unstemmed Population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle
title_sort population ecology of arctic ground squirrels in the boreal forest during the decline and low phases of a snowshoe hare cycle
publishDate 1997
url http://hdl.handle.net/2429/7269
geographic Arctic
geographic_facet Arctic
genre Arctic ground squirrel
Arctic
genre_facet Arctic ground squirrel
Arctic
op_rights For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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