Meeting Abstract

P2.151  Tuesday, Jan. 5  Effect of presence of post-hibernation food availability on reproductive development in male arctic ground squirrels (Urocitellus parryii). RICHTER, M.M.*; KOHL, F.; BUCK, C.L.; BARNES, B.M.; University of Alaska Fairbanks; University of Alaska Fairbanks; University of Alaska Anchorage; University of Alaska Fairbanks mmrichter@alaska.edu

The proportion of wild male arctic ground squirrels (Urocitellus parryii) (AGS) that become reproductively mature as yearlings is 50 to 100% in any given year. Males that do not become reproductively mature end their heterothermy 3-4 weeks before emerging above ground during which they eat cached food, recoup body mass lost over winter and develop spermatogenic testes. Males that fail to initiate reproductive development their first year end heterothermy six or more weeks later and emerge from hibernation directly after becoming euthermic at 70-50% of their pre-immergent mass. We tested the hypothesis that the presence or absence of available food determines whether juvenile males become reproductively mature in spring. Wild-caught juvenile male AGS were placed in a cold chamber (2°C) in fall and allowed to hibernate. In February, one group was given a cache of 200g of food, while the other group had all food removed from their cages. Upon terminal arousal in spring, all animals were weighed, sampled for blood and evaluated for reproductive status every 5 days for 20 days. Animals in the group that did not receive a cache were placed on a diet to maintain weight. Our results suggest that the presence or absence of ad libitum food after heterothermy ends is not essential for an animal to undergo reproductive maturation. There was a trend for pre-hibernation body mass to influence the end date of heterothermy (p=0.062), but not the date of entry (p=0.49) or the overall duration of heterothermy (p=0.109). January body mass, however, did not differ between animals that became reproductively mature and those that did not (p=0.191).