Social Development in Newborn Bats

For many social mammals, the development of social contacts among group members occurs early in life. Once formed these social bonds may last a lifetime and are often important for survival. Such is the case in baboon troops, elephants, and many other highly social mammals.

Many species of
vespertilionid bats are highly social, yet we know little about how social structure is established in these groups. One way to address this question is to study the distance between newborn bats in the nursery colony and their later social relationships as adults. That’s just what Ancilloctto, Serangeli, and Russo (2012) did with a nursery colony of Kuhl’s pipistrelle (Pipistrellus kuhlii) in Europe (Figure 1).

pipistrellus-kuhlii-2008-03-12-luhansk-zagorodniuk
Figure 1. A closeup photo of a Kuhl’s pipistrelle (Pipistrellus kuhlii). (From Igor Zagorodniuk)

Four groups of 1-3 day old newborn bats were housed in four separate groups; three groups consisted of individuals from different colonies and one group included individuals from the same colony. No contact, or olfactory cues were allowed between groups for the 6 week weaning period. At weaning, each bat was uniquely marked with colored plastic wing bands and released into a large common flight room.

The researchers recorded which bats roosted together, and interacted with each other in the flight room during the daytime. Bats that had been reared together were more likely to huddle together or show other forms of amicable behavior (allogrooming) than bats that had been reared apart prior to weaning (Figure 2).

bat_nursery
Figure 2. Mean frequencies of same-sex (top row) and different-sex (bottom row) interactions broken down by intra-group or inter-group rearing status. Black bars are males and gray bars are females. (From Ancillotto et al., 2012)

Females were more likely to interact positively with other females. These results suggest that the position of a newborn within a nursery cluster may influence the formation of adult social ties. This may have important implications for new colony formation. In short, social interactions between nursery-mates early in life sets the stage for adult sociality.


References

Ancillotto, L., Serangeli, M., & Russo, D. (2012). Spatial Proximity between Newborns Influences the Development of Social Relationships in Bats Ethology DOI: 10.1111/j.1439-0310.2011.02016.x