Social behaviour of a colony of the yellow-bellied marmot ( Marmota flaviventris)

Abstract

The social behaviour of a colony of yellow-bellied marmots was studied from June 18th to August 30th, 1955; July 12th to August 24th, 1956; June 10th to August 23rd, 1957; and June 14th to August 21st, 1961. The colony is located along a river terrace near the south entrance of Yellowstone National Park on the east side of the Snake River slightly south of the junction of the Lewis and Snake Rivers. The home-burrow is where the young are reared, where an animal normally spends the night, and where an animal goes when an alarm call is given. Auxiliary burrows are used temporarily as a place of refuge. The burrows are connected by a trail system that directs the movements of the animals. The distribution of adults and litters indicated a preference for burrows in the central part of the colony. Patterns of home range were of three types, those with no overlap, those with slight overlap and those with major overlap. Animals which utilized the same home range frequently avoided one another. The shape of the home range depended primarily on the nearness of the feeding area. Agonistic behaviour modified both size and shape of home ranges. Some home ranges were larger when the population was more dense or when agonistic behaviour was more frequent. Patterns of home range tended to change during the first two weeks of August when some animals hibernated. Changes in home range from year to year were correlated with changes in the individuals occupying home-burrows. The animals emerged from their burrows at about sunrise. There was a morning peak of activity followed by a midday low with a subsequent second peak of activity in the late afternoon. All the animals entered their burrows by 30 minutes after sunset. Communication between marmots involved the senses of sight, smell, touch, and, most importantly, hearing. The alarm call was given in response to any kind of intrusion into the life of the colony. No particular animal acted as a sentinel. Olfactory communication consisted of the “greeting” in which two animals sniffed each other's cheeks. One or two animals were dominant. Several tended to be submissive to all with which they had contact. Females with young may be aggressive in the vicinity of their home-burrows toward other animals, but may be submissive in other parts of the colony. Other relationships seem best characterized by a kind of neutrality in which each of the two animals avoids the other. Dominance is characterized by independence of action, tail flagging and grooming. Submissiveness is characterized by avoidance of other animals, slinking posture with tail down and submission to being groomed. Territorial behaviour does not seem to occur in the yellow-bellied marmot. Hibernation began in the second week of August. Conflicts and alert calls were less numerous and activity in general greatly decreased. Increased wandering was shown by some adults. It is postulated that agonistic behaviour is one of the factors that limits the number of marmots on a colony site.