Late Pleistocene heather vole,Phenacomys, on the North Pacific Coast of North America: environments, local extinctions, and archaeological implications

Abstract

<i>Phenacomys</i> cf. <i>intermedius</i> (Merriam 1889), the heather vole, is known from three late Pleistocene and early Holocene localities on Vancouver Island, British Columbia, Canada, where they are absent today. This study describes the heather vole specimens from one of these sites, P2 Cave, and provides a human behavioural context for its presence and eventual extirpation as a consequence of changing environments. <i>Phenacomys</i> is a cold-adapted rodent. The early Holocene thermal maximum and subsequent development of coastal western hemlock forests contributed to its Vancouver Island extinction without an apparent corresponding range restriction in higher elevation habitats as has been noted elsewhere in Western North America. Tendencies for low population densities in closed-canopy forests, anti-social intraspecies behaviours, and limited immigration from the mainland would have supported its local extinction. The absence of heather vole in the modern environment elsewhere along the coasts of British Columbia, Southeast Alaska, and Washington are probably due to similar factors as are highlighted here. This study suggests that humans are unlikely to have occupied the Vancouver Island area during a hiatus in the vertebrate faunal record from about 19,700 to 14,700 years ago when the Cordilleran Ice Sheet expanded west to the continental shelf. It also suggests that the glacial conditions in which the heather vole occupied the island diverge from the Holocene interglacial setting that saw an expansion of a human presence and of the corresponding archaeological record.

New age constraints for human entry into the Americas on the north Pacific coast

“…As the CIS expanded westward and covered Vancouver Island, vertebrate faunas perished or relocated to unglaciated areas. Vertebrates recolonized northeast Vancouver Island as early as about 14.9 ka ago 90 , 91 and northwest Vancouver Island by about 14.36 ka ago 92 . Several species including mountain goats 93 , deer mice 94 , and brown bears 90 probably arrived on Vancouver Island from south of the CIS margin.…”