58.5 Jan. 6 Seasonal changes in the reproductive organs and body condition of northern redbacked voles (Clethrionomys rutilus) in coastal, southcentral Alaska NAY, L.A.I.; STEVENSON, K.T.*; VAN TETS, I.G.; Kotzebue High School, Kotzebue, AK; University of Alaska Fairbanks/ University of Alaska Anchorage; University of Alaska Anchorage email@example.com
Arvicoline rodents (voles and lemmings) are small, non-hibernating mammals that play important ecological roles in high-latitude environments. Vole reproduction can be species-specific and generally occurs in spring and summer, but almost all arvicolines are known to at least occasionally breed in winter. Our aim was to determine whether seasonal change occurs in the relative reproductive organ masses of the northern redbacked vole (Clethrionomys rutilus) in coastal, southcentral Alaska (61°N), and, if so, to test whether these masses were correlated with the rodents' body condition. We measured seasonal change in the masses of three male organs (seminal vesicle, testis, and epididymis) and two female organs (ovary and uterus) for adult and subadult voles, used histological methods to define male reproductive state, and measured body condition (percentage body fat) using dual-energy X-ray absorptiometry (DXA). The relative masses of all male and female organs showed significant seasonal change (P < 0.05), but there was no correlation between any of the relative organ masses and the voles' body fat percentage (P > 0.05, R2 = 0.0 to 0.1). All of the male and female organ masses were significantly heavier in the Spring and Early Summer seasons. Reproductive condition was tightly linked to season but not to body condition. The reproductive condition of northern red-backed voles may continue to follow season by responding to changes in photoperiod, regardless of any changes in the energetic demands placed on the animal due to climate change.