Meeting Abstract
Animals living in polar regions, such as arctic ground squirrels (Urocitellus parryii), are exposed to extreme seasonal changes. As the northernmost hibernating small mammal, arctic ground squirrels are only active three to five months of the year when environmental conditions are favorable. During their short active season, arctic ground squirrels must rapidly transition through life history stages as they reproduce and subsequently prepare for the next hibernation cycle. Prior studies indicate that male and female ground squirrels differ in when and how they allocate energy towards reproduction. Therefore, we predicted that these sex-specific differences in reproductive requirements would affect time budgets and daily energy expenditure. We equipped free-living male and female ground squirrels in northern Alaska with light loggers affixed to collars, which provide information on time spent above vs. below ground and accelerometers, which allow us to measure overall dynamic body action (ODBA), an index of energy expenditure. We found that, compared to males, females spent less time aboveground during early lactation but were more active per unit of time aboveground and had higher daily measures of ODBA. Thus, in addition to costs associated with lactation, females also have higher activity-specific energy expenditure during this interval. Overall, our results support the hypothesis that differences between the sexes in reproductive requirements influence time and energy budgets of arctic ground squirrels.
