Seasonal variation in body composition and gut capacity of the prairie vole (Microtus ochrogaster)

Prairie voles (Microtus ochrogaster) were trapped during different seasons in order to examine simultaneous variation in body composition and gut capacity. Voles in reproductive condition were trapped in May, August, and November but not in February. Body masses of adult voles were lowest during February 1994. Adult males showed no seasonal variation in absolute lipid mass but did exhibit variation in relative fat content (percent body fat), with the highest values found in February 1994. Both absolute lipid mass and relative fat content of adult females varied with month of capture and were higher in February of both 1994 and 1995. Juvenile voles showed no variation in body composition between seasons and had fat levels similar to those of adult voles in the breeding months. Wet mass of the gastrointestinal tract varied with season of capture for both adult males and females, but no distinct pattern was evident. Mass of gut contents varied between trapping periods for adult males, but there were no seasonal differences in the gut contents of adult females or juveniles. The average mass of gut contents was higher than previously reported for field-caught prairie voles; this difference is likely due to the use of snap traps versus live traps.