Black myotis  (Myotis nigricans)

The black myotis is classified as Least Concern (LC) on the IUCN Red List (1).

The black myotis (Myotis nigricans) is a relatively small bat, aptly named for its blackish fur (2) (3). However, its colouration can also vary from dark brown to light- or reddish-brown, and the underparts may be brown, cream or buff (2) (3) (4) (5). The wing and tail membranes, face and ears are blackish (3) (4).

The fur of the black myotis is smooth and somewhat silky. The tail is relatively long, but is entirely enclosed within the tail membrane, which is naked from below the level of the knees (2) (3) (4). The black myotis has tiny eyes, narrow, pointed ears, a pointed tragus in front of each ear, and no noseleaf (3) (4). The female black myotis is usually slightly larger than the male (5) (6).

A number of subspecies of the black myotis have been identified (2) (7) (8) (9). However, its taxonomy is poorly understood and further study may reveal it to comprise more than one distinct species (7) (9).

The black myotis is found in most of Central and South America, where it is reported to be the most abundant and widespread Myotis species (7). Its distribution extends from Nayarit and Tamaulipas in Mexico, south to northern Argentina, and also includes Trinidad and Tobago, Montserrat and Grenada in the Caribbean (1) (3) (5) (7) (9) (10).

This species occurs in a wide range of habitats, including most types of tropical and subtropical forest, as well as agricultural areas, gardens, savanna and scrub (1) (2).

The black myotis prefers to forage in open areas or gaps in the forest, such as those formed by streams, trails or fallen trees, and even uses clearings around buildings (1) (4) (11). It usually roosts in hollow trees, rock crevices, caves or buildings (1) (3) (4) (10), and has been recorded up to elevations of 3,150 metres (2) (3).

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).

With its large population and widespread distribution, the black myotis is not currently considered at risk of extinction. It is not known to face any major threats, and appears to be relatively resilient to the modification of its habitat (1).

The black myotis occurs in several protected areas, but there are no specific conservation measures currently targeted at this species. Some populations may need extra protection, such as the northern population in Mexico, which is a potential subspecies (1).

The taxonomy of the black myotis also needs to be revised as, if it does comprise more than one distinct species, the conservation needs of the different forms may potentially need to be reassessed (1).

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Find out more about bat conservation:

• Bat Conservation International:
  http://www.batcon.org/
• Organisation for Bat Conservation:
  http://www.batconservation.org/