The diet of the black myotis consists predominantly of flying insects, including moths, beetles and flies (1) (3) (10) (12). This species flies quickly, with rapid wingbeats (4), and captures its prey in the tail membrane before transferring it to the mouth (11). Foraging takes place at night (1) (2) (3) (10). The black myotis roosts by day in large clusters of females and young, with the males usually roosting alone or in separate bachelor groups (2) (3) (5).
In Panama, the black myotis mate in December and January, with most births occurring around February, after a gestation period of around 60 days. The females immediately become receptive again after giving birth, and further birth peaks occur between April and May and again in August. However, breeding does not then resume until December, ensuring that no young are weaned in the dry season between January and March, when insects are scarce (2) (3) (5) (10). In other parts of the black myotis’ range, birth peaks may occur at different times of the year (5) (10).
The black myotis usually gives birth to a single young at a time (5) (10). The young bat remains attached to the female for the first two or three days, after which it is left behind in a large group, or crèche, while the female leaves the roost to feed (2) (5) (13). The young black myotis is able to fly for the first time from just three weeks old (2) (5), but weaning does not occur until about five to six weeks (2) (10). This species reaches sexual maturity at around four months and has been known to live for up to seven years in the wild (2) (5).