Hoary bat  (Lasiurus cinereus)

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

The hoary bat (Lasiurus cinereus) is one of the largest and arguably most beautiful bats in the Americas (3). Its body fur is long, dense and largely grey-brown, with white tips to the hairs that give this species the frosted or ‘hoary’ appearance for which it is named (2) (3). There is a distinct patch of yellow fur on the throat, and white patches on the wrists and shoulders (2).

The ears of the hoary bat are short and rounded, and are edged in black. The tail membrane of this species is heavily furred. Female hoary bats usually average slightly larger than the males (2).

Like many bats, the hoary bat uses echolocation for navigation and to detect its prey. However, unlike in most bat species, the echolocation sounds made by the hoary bat are often audible to humans (4).

The hoary bat is one of the most wide-ranging bat species in the Americas (2) (3) (4). It is found in South America, from Argentina and Chile, north through Uruguay, Paraguay, southern Brazil, Bolivia, Peru, Colombia and Venezuela, through parts of Central America, and into most of the United States and Canada (1) (2). This species also occurs in the Galapagos Islands (1).

Interestingly, the hoary bat also occurs in Hawaii (1) (2), where it is the only native non-marine mammal (4) (5) (6).

Unlike many other bat species, the hoary bat roosts solitarily in dense vegetation, rather than in colonies in caves. It appears to avoid using caves as it often has trouble navigating its way back out. The hoary bat prefers to roost in trees at the edges of clearings, about three to five metres above the ground, but will also use tree cavities, rock crevices and even squirrel nests (1) (2) (5).

Over its extensive range, the hoary bat can be found in a wide variety of habitat types, from deserts to tropical forests (4). It generally hunts around tree tops, along streams and lakes, and in densely vegetated urban areas (1).

For such tiny animals, bats are formidable hunters. The hoary bat is most active about 5 hours after sunset (1) and may cover as much as 39 kilometres while foraging (3). Despite its generally solitary nature, the hoary bat will often form groups when hunting (1) (2). It uses echolocation to detect its prey, which usually consists of insects, particularly moths (2) (4) (7).

Although some hoary bats remain in northern areas and hibernate during winter, most appear to be migratory, travelling south at the end of the North American summer to spend the winter in warmer tropical areas (2) (3). This species migrates some of the longest distances of any bat (4). When returning north in the early spring, the female hoary bats begin migrating about a month earlier than the males (7).

The hoary bat usually mates in autumn, around the time of migration. However, after mating the female hoary bat is able to store sperm over the winter, with fertilisation not occurring until the spring, before the northward migration (2) (4). Outside of the mating season, the hoary bat is usually solitary, and males and females are rarely found together. However, the migration is one of the few times this species may form groups (2) (3) (4) (7).

The female hoary bat gives birth between May and July, usually to twins, but sometimes to up to four young. The young bats cling to the female or to a branch until old enough to fly, at around 33 days after birth (2) (4). The hoary bat is likely to live for up to six or seven years (4).

The hoary bat is not currently considered globally threatened, and is not known to face any major threats at present (1). However, it is one of the most common bat species to be killed by wind turbines (7), and it may be susceptible to deforestation and human disturbance in Mexico (1). In Hawaii, the hoary bat may face threats from habitat destruction, pesticides and introduced species, although its exact status there is not well understood (6).

Despite the potential threat to North American bat species from a disease known as ‘white-nose syndrome’, there have not yet been any recorded deaths of hoary bats due to this fungus (8).

The hoary bat is found in protected areas across its range (1).The Hawaiian subspecies (Lasiurus cinereus semotus) is listed as Endangered by the U.S. Fish and Wildlife Service (9) and is covered by a recovery plan, which recommends further studies to determine its population status and habitat requirements (6).

Find out more about bat conservation:

• Bat Conservation International:
  http://www.batcon.org/