Paleoecological implications of Late Pleistocene and Holocene microtine rodents from the Bluefish Caves, northern Yukon Territory

Abstract

Bluefish Caves 1, 2, and 3 have produced tens of thousands of vertebrate remains among which at least nine species of microtine rodents are represented: red-backed vole, Clethrionomys rutilus; collared lemming, Dicrostonyx torquatus; brown lemming, Lemmus sibiricus; singing vole, Microtus miurus; tundra vole, Microtus oeconomus; meadow vole, Microtus pennsylvanicus; yellow-cheeked or taiga vole, Microtus xanthognathus; muskrat, Ondatra zibethicus; and northern bog lemming, Synaptomys borealis. Late Pleistocene and Holocene components are clearly distinguishable from one another in each of the three caves, and each component can be subdivided within cave 1. This paper discusses ( i ) variations in taxonomic abundance through time and between site areas, (ii) contrasts in microhabitat between north-facing cave 1 and south-facing cave 2, and (iii) decreases in tooth size that may reflect a reduction in the length of the growing season. A general decrease in diversity is shown to involve increased dominance and decreased species richness and evenness. These changes are attributed to postglacial zonation of habitat.Les trois cavernes de Bluefish ont fourni des dizaines de milliers de fragments de vertCbrCs parmi lesquels sont reprCsentCes au moins neuf espkces de rongeur apparentkes aux Microtus : campagnol a dos roux, Clethrionomys rutilus; lemming variable, Dicrostonyx torquatis; lemming brun, Lemmus sibiricus; compagnol chanteur, Microtus miurus; compagnol nordique, Microtus oeconomus; carnpagnol des champs, Microtus pennsylvanicus; campagnol de la taiga ou i joues jaunes, Microtus xanthognathus; rat musquC, Ondatra zibethicus; et campagnol-lemming borCal, Synaptomys borealis. Des ClCments fossiles d'lge plCistockne et holokene ont kt6 nettement identifiCs dans chacune des trois cavernes, et les ClCments dans la caverne 1 ont pu Ctre regroupCs. Le prCsent article discute ( i ) des variations de l'abondance taxonomique en fonction du temps et entre les divers sites; (ii) des contrastes de microhabitat qui existe entre la caverne 1 faisant face au nord et la caverne 2 avec sa face au sud; et (iii) de la diminution de la dimension des dents, probablement causCe par un Ccourtement de la durCe de la saison de croissance. Le dCclin du nombre d'espbces diffkrentes est reliC 2 la dominance et B la diminution en abondance de certaines espbces et de leur CgalitC de survie. Ces changements sont attribues B une zonation postglaciaire de l'habitat.[Traduit par la revue]Can. J. Earth Sci. 26, 149-156 (1989)

Small mammals and paleovironmental context of the terminal pleistocene and early holocene human occupation of central Alaska

“…The presence of singing vole and brown lemming in Pleistocene contexts concurs with the small‐mammal record in Full Glacial sediments in central Alaska, where these two species, along with the arctic lemming, are dominant (Guthrie, ; Repenning et al, ); as well as with the karstic records from Lime Hills and Bluefish caves (Georgina, ; Morlan, ). The abundance of singing vole, in particular, has led Guthrie to associate the species with the steppe‐like graminoid dominated biome that covered Beringia during much of the late Pleistocene (Guthrie, ).…”

“…Species identification of skeletal remains of Arvicolinae (Cricetidae) was limited to the lower first molar (m1), which is diagnostic to species for most of the Arvicolinae species expected in the higher latitudes of North America (Semken & Wallace, ). Exceptions include the m1 of Microtus miurus and Microtus pennsylvanicus that are of similar shape and can overlap in size (Morlan, ).…”

“…Exceptions included small-mammal nests encountered whole during excavation, which were collected and screened in the laboratory in nested screens to a size of 63 μm. Reuther et al, 2016) Swan (Dilley, 1998;Hirasawa & Holmes, 2017;Holmes, 2014Holmes, , 2011 Upward Sun River (XBD-298) 260 240 Loess Sand dune Well-drained mixed forest of white spruce, aspen, poplar, and paper birch Dune field and floodplain Muskeg with black spruce and tussocks (Potter, Irish, Reuther, & McKinney, 2014;Potter, Irish, Reuther, Gelvin-Reymiller, & Holliday, 2011;Potter, Reuther, Bowers, & Gelvin-Reymiller, 2008;Reuther, 2013) Note: (Morlan, 1989).…”

Radiocarbon Dates on Saiga Antelope (<i>Saiga Tatarica</i>) Fossils from Yukon and the Northwest Territories

“…The climate governing their present range is extremely continental, with warm summers in which mean July temperatures reach 22˚-28˚C. Winters are severe: mean January temperatures chronostratigraphic context is relatively straightforward and similar in many ways to that of Caves I and II: a late Pleistocene, poorly differentiated loess unit containing remains of fishes, amphibians, birds and mammals (including the saiga) is overlain by a Holocene, cryoclastic rubble and humus unit characterized by an impoverished fauna of extant taxa (Cinq-Mars, 1979, 1982, 1990Cinq-Mars and Morlan, in press;Morlan, 1989;Morlan and Cinq-Mars, 1982).…”

Quaternary Cave Faunas of Canada: A Review of the Vertebrate Remains

“…The ice-age fauna of Bluefish Caves comprises four fish species, one amphibian, at least twenty-three bird species, and thirty-five mammal species, including the mammoth, the steppe bison Bison priscus, the Yukon horse Equus lambei, the Dall sheep Ovis dalli, the caribou, the moose, the wapiti, the saiga antelope Saiga tatarica, the muskox Ovibos moschatus, the steppe lion Panthera leo spelaea, the cougar Puma concolor, the brown bear, the wolf, and many smaller mammals, including nine species of microtine rodents. Stone artifacts, made of exotic, high-quality cherts, were mainly found in loess that contained remains of the Late Pleistocene vertebrate fauna (Beebe, 1983;Cinq-Mars, 1979;Cinq-Mars and Morlan, 1999;Harington and Cinq-Mars, 2008;Morlan, 1989;McCuaig-Balkwill and Cinq-Mars, 1998). …”