Hammer-headed Bat - Reproduction and Mortality

Reproduction and Mortality

Little is known about reproduction in hammer-headed bats. In some populations breeding is thought to take place semi-annually during the dry seasons. The timing of the dry season varies depending on the locality, but in general there are two breeding seasons, one from June to August and the other from December to February. However, in other populations, breeding is not restricted to dry seasons and occurs during all months of the year.

This species is often cited as a classic model of lek mating. In this type of mating system, males cluster in dense groups at specific locations known as mating arenas. In some populations of hammer-headed bats, males gather along rivers at night and display by rapid wing flapping accompanied by loud vocalizations. An arena may contain from 25 to 132 males. Females fly through the arena assessing the males. Once the female’s choice is made, the female lands on the branch and sits beside the male. Once chosen, the male emits a buzzing call and copulation ensues.

However, some populations of hammer-headed bats do not use the lek mating strategy. Males actively display but are not found clustering in groups. This species is highly polygamous. Some estimates suggest that as few as six percent of the males in a population account for up to seventy-nine percent of the matings.

Females generally produce one offspring at a time. Neither gestation nor time until weaning have been reported for this species. Females mature more quickly than males and are sexually mature after six months. They continue to grow and reach adult size at nine months. Males do not reach sexual maturity until approximately eighteen months of age and they do not obtain their unique facial morphology until twelve months. Compared with other bats, this bat is rather long-lived with an average life expectancy of thirty years in the wild.