Possible Functions of the Alarm Calls of Beldings Ground Squirrels and Prairie Dogs

Player, Rod

Alarm calls, which are vocalizations that alert other animals of danger, have the appearance of altruism. Altruistic behavior can be defined as behavior that benefits another organism, not closely related, while being apparently detrimental to the organism performing the behavior. Trivers (1971) and Sherman (1977) have written on the possible evolutionary routes leading to the giving of alarm calls as it is related to altruistic behavior. Before the possible evolutionary routes of alarm calling be discovered it is necessary to determine the exact function of the calls. Identifying the function of alarm calls is difficult because predation is rarely seen in the field, and it is also difficult, with most species, to identify individuals and their relatedness. During a three-year field study, Sherman (1977) investigated the function of the alarm call of the Belding's ground squirrel (Spermophilus beldingi) that was given when a terrestrial predator approached. The ground squirrel population he studied contained individually marked animals of known age and familial relationships. This paper is a review of Sherman's work as compared to the literature concerning alarm calls of the prairie dog (Cynomys sp.).