A maternity colony refers to a temporary association of reproductive female bats for giving birth to, nursing, and weaning their pups. The colonies are initiated by pregnant bats. After giving birth, the colony consists of the lactating females and their offspring. After weaning, juveniles will leave the maternity colony, and the colony itself will break apart. The size of a maternity colony is highly variable by species, with some species forming colonies consisting of ten or fewer individuals, while the largest maternity colony in the world in

Bracken Cave Bracken Cave is the summer home to the largest colony of bats in the world. An estimated 20 million Mexican free-tailed bats roost in the cave from March to October making it the largest known concentration of mammals. The cave is located in sou ...

is estimated to have over 15 million bats.

Benefits of a maternity colony

Maternity colonies are especially prevalent in temperate regions due to the thermal benefits of roosting with other individuals.Dietz, M., & Kalko, E. K. (2006). Seasonal changes in daily torpor patterns of free-ranging female and male Daubenton’s bats (Myotis daubentonii). Journal of Comparative Physiology B, 176(3), 223-231. Outside of the winter months, non-reproductive females and male bats enter

torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the time ...

for short periods to conserve energy when temperatures are below an optimum threshold. However, torpor is detrimental to reproductive females because it delays the development of the fetus and slows milk production. Therefore, female bats are highly incentivized to maintain a constant body temperature. Roosting in a large group allows females to share body heat, lowering the energetic costs for individuals.

Risks of a maternity colony

Roosting in large groups brings risks to the members of a maternity colony. Predators such as hawks and owls can learn to anticipate the emergence of bats from a specific roost at sunset.Fenton, M. B., Rautenbach, I. L., Smith, S. E., Swanepoel, C. M., Grosell, J., & Van Jaarsveld, J. (1994). Raptors and bats: threats and opportunities. Animal Behaviour, 48(1), 9-18. Smaller colonies are thought to be less risky than larger colonies, because the nightly emergence of bats would attract less attention.Wilkinson, G. S., & South, J. M. (2002). Life history, ecology and longevity in bats. Aging cell, 1(2), 124-131.

Species that form maternity colonies

References

{{reflist Bats