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How does hibernation affect reproduction in bats?

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The image shows a group of Virginia big-eared bats sleeping upside down in a dark cavern. — Dormancy Virginia big-eared bats (*Corynorhinus townsendii virginianushibernating*) are true hibernators, entering a state close to death for much of the winter.

In most hibernating bat species, the reproductive cycle is specifically adapted to the period of dormancy. In these bats, gonadal activity in males peaks in the fall, which is when mating occurs. Following copulation, the sperm is stored within the female’s reproductive tract throughout the winter hibernation period. Ovulation, fertilization, and implantation are delayed until the spring, when the bats emerge from hibernation and have access to warmer roosts and abundant food supplies, which significantly improves the survival chances of the young.12

A notable exception is the vespertilionid bat (Miniopterus), where ovulation and fertilization occur in the fall shortly after mating. In this species, embryonic development begins during hibernation but proceeds at a slowed rate rather than ceasing entirely. This process results in a gestation period that is several months longer than that of non-hibernating tropical relatives.1