Pika (Ochotona)

Abstract

Two species of pika, Ochotona princeps and O. collaris, are distributed in the mountains of western North America. Pikas are restricted to talus or piles of broken rock surrounded by suitable vegetation. Individuals maintain territories on talus that are of approximately equal size independent of sex. Pikas of all sexes and ages may, during any season, engage in long distance forays. Daily activity of pikas depends on temperature. They are most often active at dawn and dusk, avoiding midday high temperatures. Carrying capacity of pikas is fixed because of their habitat specificity and territorial nature. Behavioral mechanisms subserving territorial advertisement and defense include vocalization, scent marking, and active chases and fighting bouts with conspecific intruders. Observations on unmarked animals are inappropriate because of the frequent forays by all sexes and ages away from their territory or nest site and the asymmetries of such movements.