Landscape drivers of site occupancy by remnant populations of arctic ground squirrels (Urocitellus parryii)

AbstractMiddens (nests and caches) of Late Pleistocene arctic ground squirrels (Urocitellus parryii) that are preserved in the permafrost of Beringia archive valuable paleoecological data. Arctic ground squirrels selectively include the plant material placed in middens. To account for this selectivity bias, we used a multi-proxy approach that includes ancient DNA (aDNA) and macro- and microfossil analyses. Here, we provide insight into Pleistocene vegetation conditions using macrofossils, pollen, phytoliths and non-pollen palynomorphs, and aDNA collected from one such midden from the Yukon Territory (Canada), which was formed between 30,740 and 30,380 cal yr BP. aDNA confirmed the midden was constructed by U. parryii. We recovered 39 vascular plant and bryophyte genera and 68 fungal genera from the midden samples. Grass and other herbaceous families dominated vegetation assemblages according to all proxies. aDNA data yielded several records of vascular plants that are outside their current biogeographic range, while some of the recovered fungi yielded additional evidence for local occurrence of Picea trees during glacial conditions. We propose that future work on fossil middens should combine the study of macro- and microfossils with aDNA analysis to get the most out of these environmental archives.

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Tissue-specific telomere dynamics in hibernating arctic ground squirrels (Urocitellus parryii)

Journal of Experimental Biology ◽

10.1242/jeb.204925 ◽

2019 ◽

Vol 222 (18) ◽

pp. jeb204925

Author(s):

Sara M. Wilbur ◽

Brian M. Barnes ◽

Alexander S. Kitaysky ◽

Cory T. Williams

Keyword(s):

Ground Squirrels ◽

Tissue Specific ◽

Urocitellus Parryii ◽

Arctic Ground Squirrels ◽

Telomere Dynamics

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Evidence for source - sink dynamics in a regional population of arctic ground squirrels (Urocitellus parryii plesius)

Wildlife Research ◽

10.1071/wr11167 ◽

2012 ◽

Vol 39 (2) ◽

pp. 163 ◽

Cited By ~ 14

Author(s):

Scott A. Donker ◽

Charles J. Krebs

Keyword(s):

Boreal Forest ◽

Radio Telemetry ◽

Geographic Area ◽

Ground Squirrels ◽

Habitat Types ◽

Alpine Meadows ◽

Context Variable ◽

Urocitellus Parryii ◽

Arctic Ground Squirrels ◽

Source Sink

Context Variable demographic rates can manifest themselves between habitat types in the form of source–sink dynamics where populations in sink habitats would not exist without the addition of migrants from source habitats. Aims Arctic ground squirrels (Urocitellus parryii pleisus (Osgood, 1900)) occupy a large geographic area in northern Canada and live in a variety of habitat types, including boreal forest, low-elevation meadows and alpine meadows, providing an opportunity to investigate the possible existence of source–sink dynamics. Methods We hypothesised that arctic ground squirrels in the south-western Yukon exhibit demographic characteristics indicative of source–sink dynamics. Boreal forest habitat could be a sink in spite of previous high squirrel densities, whereas meadows could be a source. We investigated this by mark–recapture live-trapping and radio-telemetry. Key Results In the boreal forest in the Kluane region, we found reduced recruitment, reduced population growth rates (λ), and reduced survivorship for radio-collared individuals that moved from low-elevation meadows into the boreal forest. There was no evidence from radio-collared juveniles of dispersal from high-density ground squirrel populations in alpine meadows down into boreal forest. Conclusions Boreal forest is a sink habitat for arctic ground squirrels. Source–sink dynamics observed between low-elevation meadow and boreal forest habitats appear to result from increased predation pressure in the boreal forest. The result has been a near extirpation of boreal forest arctic ground squirrels in the Kluane region since 1998. Implications Because the source areas of low-elevation meadows occupy only 7–9% of the lowland habitat, recolonisation of boreal forest sites has been very slow. Whereas alpine populations remain high in 2011, boreal forest populations remain near zero. Alpine populations do not appear to be a source for the boreal forest.

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Habitat-specific distribution and abundance of arctic ground squirrels (Urocitellus parryii plesius) in southwest Yukon

Canadian Journal of Zoology ◽

10.1139/z11-041 ◽

2011 ◽

Vol 89 (6) ◽

pp. 570-576 ◽

Cited By ~ 12

Author(s):

S.A. Donker ◽

C.J. Krebs

Keyword(s):

Boreal Forest ◽

Alpine Meadow ◽

Ground Squirrels ◽

Habitat Types ◽

Alpine Meadows ◽

Specific Distribution ◽

Snowshoe Hares ◽

Urocitellus Parryii ◽

Low Altitude ◽

Arctic Ground Squirrels

Arctic ground squirrels ( Urocitellus parryii plesius (Osgood, 1900); formerly Spermophilus parryii plesius Osgood, 1900) were studied in three distinct habitat types (boreal forest, low-elevation meadows, and alpine meadows) in the Kluane region of the southwest Yukon Territory, Canada, from 2008 to 2010 to determine if populations in these different habitats provide evidence for habitat-specific distribution and abundance. Abundance in the boreal forest has been shown to be synchronous with the cycle of snowshoe hares ( Lepus americanus Erxleben, 1777) in the region owing to shared predators. We predicted that populations in the boreal forest would be low because of the current low phase in the cycle of snowshoe hares, and that in low-altitude meadows and alpine meadows, ground squirrels would be relatively abundant. Late-summer densities differed significantly between habitat types with 0.38 ± 0.13 squirrel/ha (mean ± 1 SE) in boreal-forest habitat, 1.25 ± 0.22 squirrel/ha in low-altitude-meadow habitat, and 5.7 ± 0.22 squirrels/ha in alpine-meadow habitat. In 2009, populations were extirpated from boreal-forest habitat, while densities in low-elevation meadows and alpine meadows were 1.6 ± 0.34 squirrel/ha and 6.1 ± 0.7 squirrels/ha, respectively. The current absence of squirrels from the boreal forest and the persistence of populations in low-elevation-meadow and alpine-meadow habitat suggest that source–sink dynamics may exist between boreal-forest and meadow habitat types.

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Environmental heterogeneity affects seasonal variation in thyroid hormone physiology of free-living arctic ground squirrels (Urocitellus parryii)

Canadian Journal of Zoology ◽

10.1139/cjz-2018-0302 ◽

2019 ◽

Vol 97 (9) ◽

pp. 783-790 ◽

Cited By ~ 1

Author(s):

Cory T. Williams ◽

Helen E. Chmura ◽

Victor Zhang ◽

Danielle Dillon ◽

Kathryn Wilsterman ◽

...

Keyword(s):

Life History ◽

Environmental Heterogeneity ◽

Ground Squirrels ◽

Free Living ◽

Life History Stages ◽

Total Thyroxine ◽

Primary Driver ◽

Lactating Females ◽

Urocitellus Parryii ◽

Arctic Ground Squirrels

Thyroid hormones (TH) are key regulators of metabolism that could play an important role in altering physiology and energy allocation across life-history stages. Here, we examine seasonal TH dynamics from 345 plasma samples collected from 134 free-living arctic ground squirrels (Urocitellus parryii (Richardson, 1825)) across three consecutive years (2014–2016). We also examine whether unbound levels of triiodothyronine (free T3) in plasma are correlated with total T3 levels and total thyroxine (T4) levels, and whether fecal T3 metabolite levels correlate with plasma TH levels. We found significant differences in plasma TH levels across stages of the annual cycle, but these differences were highly inconsistent across years. However, within a given time period, pregnant females had lower free T3 levels compared with lactating females. We also found that although free T3 was correlated with both total T3 and total T4 in plasma, fecal T3 was not positively correlated with plasma TH levels. Given the lack of consistent differences across life-history stages, we suggest environmental heterogeneity may be the primary driver of TH dynamics, masking any potential endogenous seasonal rhythms in TH secretion. We urge caution in the use of fecal T3 metabolites as a proxy for circulating levels and encourage further research to understand the observed discrepancy.

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Use of Arctic ground squirrels (Urocitellus parryii) by brown bears (Ursus arctos)

Polar Biology ◽

10.1007/s00300-014-1593-8 ◽

2014 ◽

Vol 38 (3) ◽

pp. 369-379 ◽

Cited By ~ 1

Author(s):

Oliver E. Barker ◽

Andrew E. Derocher ◽

Mark A. Edwards

Keyword(s):

Ursus Arctos ◽

Ground Squirrels ◽

Brown Bears ◽

Urocitellus Parryii ◽

Arctic Ground Squirrels

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Forest or meadow: the consequences of habitat for the condition of female arctic ground squirrels (Urocitellus parryii plesius)

Canadian Journal of Zoology ◽

10.1139/cjz-2015-0100 ◽

2015 ◽

Vol 93 (10) ◽

pp. 791-797 ◽

Cited By ~ 3

Author(s):

Jeffery R. Werner ◽

Charles J. Krebs ◽

Scott A. Donker ◽

Michael J. Sheriff

Keyword(s):

Boreal Forest ◽

Body Condition ◽

Boreal Forests ◽

Compensatory Growth ◽

Ground Squirrels ◽

The Body ◽

Urocitellus Parryii ◽

Wildlife Populations ◽

Arctic Ground Squirrels ◽

Source And Sink

Body condition of animals influences the likelihood of surviving harsh environmental conditions, successfully reproducing, and resisting disease. The sum of these individual components of fitness, in turn, have consequences for the growth and persistence of wildlife populations. Here we compared the body mass and condition of adult female arctic ground squirrels (Urocitellus parryii plesius (Osgood, 1900)), an obligate hibernator, in source and sink habitats. We tested the hypothesis that adult females would be in poorer condition in the boreal forest than in adjacent meadows. We found that, during spring, postpartum females in forests weighed less (405 ± 7 vs. 437 ± 11 g; mean ± SE) and were in poorer condition (mean (±SE) residual of mass over structural size = −11.0 ± 10.2 vs. 20.5 ± 6.1 g) compared with females in meadow-source habitat. However, by the onset of entrance into hibernation in August, forest squirrels had reached parity with meadow squirrels and no difference was found in mass (519 ± 13 vs. 520 ± 15 g; mean ± SE) or condition (residual index = −0.01 ± 0.01 vs. 0.03 ± 0.01; mean ± SE). We suggest that for squirrels in formerly occupied boreal forests, (i) poor spring body condition decreased reproductive success and (ii) achieving compensatory growth, via increased foraging, comes at the costs of higher predation risk. These costs likely contributed to the recent local extinction of arctic ground squirrels in boreal forest habitat.

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