Greater Bulldog Bat, Noctilio leporinus

The greater bulldog bat (Noctilio leporinus), also known as the fisherman bat, is native to Latin America. Its range extends from Mexico to northern Argentina, and includes most of the Caribbean Islands. Despite its large range, its distribution is fragmented due to its preferred habitats with an abundance of water. The greater bulldog bat is threatened by deforestation, water pollution, and changing water levels, but with no immediate danger and a large range, the IUCN has placed it as a species of “Least Concern” on the IUCN Red List.

The greater bulldog bat can weigh between 1.7 and 3.1 ounces and reach an average body length of up to five inches. Males are typically larger than females, and both sexes differ in color. Males have orange dorsal fur, while females have greyish dorsal fur. Both males and females have pale underbellies, and some individuals bear a grey stripe that extends from the neck to the base of the tail. The ears are pointed and bear a ridged tragus. This bats name is derived from the skin fold that splits the upper lip and the wart like skin that extends to the chin from the bottom lip. The wingspan of the greater bulldog bat can be up to three feet and each wing holds a long third digit. The flight patterns of this bat are slow, but it is an adept swimmer that will use its wings to paddle.

There are many color variants of this bat that are considered subspecies.  Populations in the Caribbean Basin, known as N. l. mastivus, are pale in color, while populations in Guianas and the Amazon Basin, known as N. l. leporinus, are smaller and dark in color. The subspecies N. l. rufescens can be found in northern Argentina, eastern Bolivia, and southern Brazil and are large and pale in color.

The greater bulldog bat can often be seen flying over water sources like coastal lagoons, ponds, streams, and estuaries. It forms colonies that can number in the hundreds that roost within hollow trees or deep-sea caves. As is typical with bats, the greater bulldog bat is nocturnal, and females roost separately from males, although each colony has a resident male. Males can remain with a female colony for as much as two or more breeding seasons, but bachelor males will roost and forage separately. Females will forage either alone, or in small groups with other roost mates.

The breeding season or the greater bulldog bat occurs in fall or winter, with most births occurring in January. Females will have up to one pup a year that remains in the roost until one month of age, when it begins to fly. Both the male and female parent bats will raise the pup.

The greater bulldog bat is able to emit three frequencies of echolocation, in either a constant frequency (CF) pattern or a frequency-modulated (FM) pattern, or a mixture of both (CF-FM). The CF pattern is the longest, reaching up to 17 milliseconds, while the CF-FM pattern will vary in length, with the CF lasting 8.9 milliseconds and the FM lasting 3.9 milliseconds.

The greater bulldog bat derives its other common name, the fisherman bat, from its unique adaptation to consume fish. During the wetter seasons, it will mainly consume moths and beetles, but in dry seasons, it prefers to consume fish, scorpions, and sometimes shrimp. When catching fish, the bat will fly in circles until a target has been located, and will then move towards the water and use echolocation to find the fish. It may store food in specialized cheek pouches.

Image Caption: Greater Bulldog Bat or Fisherman Bat, Noctilio leporinus (Linnaeus, 1758), adult, captive specimen, originally captured from Puerto Rico, photographed in the United States. Credit: Susan Ellis/Wikipedia(CC BY 3.0)