Fruit-eating Bat Artibeus Research Articles

Roosting behavior and group stability of the big fruit-eating bat Artibeus lituratus (Chiroptera: Phyllostomidae)

The roosting behavior of the big fruit-eating bat, Artibeus lituratus (Phyllostomidae, Stenodermatinae) in an Andean region of Venezuela is described. Sixty-four video recordings made at three separate foliage roosts during 1 year showed that group size varied between two and 14 individuals. One male was regularly observed roosting with more females than others, and this male was associated with the highest quality roost, defined here as the highest, most structurally stable, and least disturbed. Males invariably occupied exclusive roosts during the study, whereas females frequently moved among adjacent roosts. The high roost fidelity of males appears to be related to the defense of the highest quality roosts. Because females were observed roosting with each of the three males present at the study site, female groups were considered unstable. We suggest that shuttling movements of individuals may reflect a commonly observed adaptation of foliage roosting bats related to the avoidance of predators and/or parasites. The type of male–female association observed in A. lituratus is consistent with a resource defense polygyny hypothesis.

Female interactions in harem groups of the Jamaican fruit-eating bat, Artibeus jamaicensis (Chiroptera: Phyllostomidae)

ABSTRACT Harem groups of the Jamaican fruit-eating bat (Artibeus jamaicensis) are well-defined units that occupy different crevices in caves. For two consecutive years, we analyzed the non-random associations among female bats and their interactions with other members of the harem. Female members occupying the edges of the harems came from different parts of the cave and were more frequently expelled from the roosting site. Females from the central core of the harem were attacked less often and received more affiliative interactions. Females occupying areas between the central core and the edges were the most active in repelling arriving females and were responsible for grooming the central core females. During the breeding season, aggressive activities decreased and females became more tolerant, which suggests that a potential benefit of roosting together is that it provides for a more suitable place to nurse newborns, because all females produce a better environment, in thermoregulatory ways.

Reproduction elevates the corticosterone stress response in common fruit bats

Changes in reproductive state or the environment may affect the sensitivity of the hypothalamic-pituitary-andrenal (HPA) axis. However, little is known about the dynamics of the resulting corticosteroid stress response, in particular in tropical mammals. In this study, we address the modulation of corticosterone release in response to different reproductive conditions and seasonality in 326 free-living common fruit-eating bats (Artibeus jamaicensis) on Barro Colorado Island in Panama during dry and wet seasons. We present strong evidence that stress sensitivity is primarily modulated by reproductive condition. In reproductively active females, corticosterone increases were more rapid and reached higher levels, but also decreased significantly faster than in inactive females. The corticosterone response was weaker in reproducing males than in females and delayed compared to non-reproductive males. Testes volume in reproductively active males was negatively correlated with corticosterone concentrations. Our findings suggest differentiated dynamics in the corticosterone stress response between sexes, potentially reflecting conflicting ecological demands. In females, a strong acute corticosterone response may represent high stress- and risk-sensitivity that facilitates escape and thus helps to protect reproduction. In males, suppression during reproductive activity could reflect lowered stress sensitivity to avoid chronically elevated corticosterone levels in times of frequent aggressive and therefore costly inter-male encounters.