Matsunami Sh., Oshida T., Ichikawa H. 2009. Comparative skull morphology of two pika species (Ochotona princeps and O. hyperborea): implications for differences in feeding habits // Russian J. Theriol. Vol.7 (for 2008). No.2: 99–106 [in English].
Shohei Matsunami, Laboratory of Wildlife Ecology, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan [present address: Laboratory of Animal Behavior and Intelligence, Department of Biology, Faculty of Science Hokkaido University];
Tatsuo Oshida [oshidata@obihiro.ac.jp], Laboratory of Wildlife Ecology, Obihiro University of Agriculture and Veterinary Medicine, Obihiro 080-8555, Japan;
Hideo Ichikawa, Botanic Garden, Field Science Center for Northern Biosphere, Sapporo 060-0003, Japan.
KEY WORDS: American pika, northern pika, chewing muscles, cranium, mandible.
ABSTRACT. To examine the hypothesis that cranium and mandible morphology influence different feeding habits in pikas, we compared two samples: Ochotona princeps from California and Nevada, USA and O. hyperborea from Hokkaido, Japan. These pika species show similar ecological traits, are allopatrically distributed in Northern Hemisphere, and inhabit rocky hillsides on mountain. Of all measurements, 55% showed no significant differences, indicating the two samples had similarly sized and shaped skulls. Measurements with significant differences were related to origins and terminations of chewing muscles. Morphological differences between these two samples may result from differences in feeding habits.