Seasonal patterns of activity and body mass in the plains vizcacha, Lagostomus maximus (family Chinchillidae)
Activity patterns of adult male, adult female, and immature plains vizcacha (Lagostomus maximus) were compared throughout the year, and seasonal changes in body mass were documented for adults. All sex–age classes spent more time feeding in winter and less time at the den site (vizcachera) than in other seasons. The pattern was reversed for summer. Seasonal changes in activity budgets for males were associated with an increase in male–male conflicts and territorial displays at the vizcachera. Body mass of males declined in summer, when they were competing for access to areas used by females, and reached a minimum during the fall breeding season. Females spent less time foraging and more time at the den site after parturition in spring. Body mass of females did not change significantly with season. Throughout the year, activity patterns were similar for females and immatures. During all seasons, adult males spent less time foraging and more time at the vizcachera than other sex–age classes did. From a variety of observations, I suggest that the costs of reproduction, including mass loss, shorter feeding time, and short tenure in a social group, are high for male vizcachas.