AbstractPikas (Ochtona)—small gnawing mammals, related to rabbits—range today throughout parts of the Northern Hemisphere, but had a wider distribution during the Pleistocene. Nine caves from northeastern North America (a region not occupied by pikas today) have Pleistocene deposits containing remains of Ochotona. We examine 526 fossil specimens (ranging in age from approximately 850,000 to 8670 yr B.P.) from five of these caves. Two morphological forms of Ochotona lived in northeastern North America during the late Pleistocene—a large species (probably O. whartoni) and a small species (probably O. princeps).Ochotona of glacial age are not necessarily indicative of talus slopes and mesic communities. O. princeps-like of the Irvingtonian of West Virginia were living with an amphibian-reptilian assemblage found in the area today, implying winters not much, if at all, colder than at present. Late glacial and postglacial change in climate south of the ice sheets in effect would have isolated Ochotona in eastern North America, where they were unable to retreat to the west or north. Whereas western pika had the option of moving up in elevation, into boreal islands, eastern forms became restricted to ever-diminishing habitats, culminating in extinction and extirpation. Radiocarbon ages imply that Ochotona lived in eastern North America during the late Pleistocene (late Rancholabrean) and into the earliest Holocene. We describe the youngest remains of Ochotona in eastern North America and the youngest for the extinct large form, O. whartoni.
Late-Pleistocene Environments of North Pacific North America. An Elaboration of Late-Glacial and Postglacial Climatic, Physiographic and Biotic Changes.