Population regulation and annual cycles of activity and dispersal in Arctic ground squirrels

Jeffrey Emil Green
Dispersal has been implicated as one of the potentially important factors of population regulation. Interactive behaviours, particularly aggression, have been suggested as the ultimate cause of dispersal. To determine if social behaviour is related to dispersal and to population regulation, I conducted a study of the population changes and behaviour of two populations of Arctic ground squirrels, Spermophilus undulatus, in Kluane National Park, Yukon Territory, Canada. Within each study site, I
more » ... each study site, I established a control area and one experimental area in which resident animals were removed at regular intervals. On one site, I conducted two additional experiments. One involved the provision of an additional food supply and the other, a continuous removal of all adult males. The annual activity pattern of Arctic ground squirrels in the Kluane region was characterized by a 7-8 month period of hibernation, emergence, establishment of territories, a short breeding period, development and emergence of young, restoration of fat deposits, establishment of fall territories and entry into hibernation. Two peaks of aggressive behaviour, as evidenced by interaction rates and wounding occurred, both coincident with the establishment of territories. The number of resident breeding adults changed little during the two and a half years of this study. Some fluctuations in the total population occurred as a result of mature animal and juvenile dispersal and recruitment of young. Four possible sources of in situ loss were investigated; predation, disease. starvation and dispersal. Loss due to disease or starvation was negligible. Interspecific predation accounted for an estimated 10-15% of the total annual loss. The three measures of dispersal; immigration to removal and control areas and emigration to control areas showed similar seasonal peaks. The correlation between the three measures indicates that dispersal is the major cause of in situ loss. Mature females dispersed roost in flay and June. Dispersal of mature females was related t [...]
doi:10.14288/1.0094007 fatcat:6gtri7qti5bxhjg5zebxxru4tq