UBC Theses and Dissertations
Arctic ground squirrels in the Southwest Yukon Territory : evidence for habitat specific demography and source-sink dynamics Donker, Scott A.
Arctic ground squirrels (Urocitellus parryii plesius) of the southwest Yukon Territory occupy three distinct habitat types: boreal forest, low elevation meadows and alpine areas. Populations in boreal forest habitat have been shown to be synchronous with the 10-year snowshoe hare (Lepus americanus) cycle in the region due to shared predators. Relatively little is known about arctic ground squirrel populations occupying low altitude meadow and alpine meadow habitat types. Since 2000, populations in the boreal forest have remained low and in some locations have been extirpated. The first objective of this study was to investigate the distribution and abundance of arctic ground squirrels in different habitats over a large spatial scale. Density and relative abundance data were collected at numerous locations in boreal forest, low elevation meadow and alpine meadow habitat types. Populations in the boreal forest were found to be extirpated while those in low elevation meadow habitat contained self-sustaining populations that were significantly larger. The extirpation of ground squirrels from the boreal forest and continued persistence of populations in low elevation meadow habitat suggests that the boreal forest may be functioning as sink habitat and that low elevation and alpine meadows are population sources. The second objective of this study was to more closely investigate the population dynamics of arctic ground squirrels in boreal forest, low elevation meadow and alpine meadow habitats. Survivorship and movement data collected provide empirical evidence for the existence of source-sink dynamics between low elevation meadow (source) and boreal forest habitat (sink). The existence of source-sink dynamics between boreal forest and low-elevation meadow habitat appears to be implicated in the current prolonged low in the 10-year snowshoe hare cycle due to sustained predation pressure in the boreal forest.
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