The lesser bulldog bat (Noctilio albiventris) is an insectivorous and occasionally carnivorous bat of the (Neotropics), ranging through Central America and northern South America. Some unique characteristics of the bat include large feet that are used to rake the surface of water to capture prey, and precise echolocation. Occasionally, the larger bats catch and consume small fish. Due to their close proximity to urban life, there are also some interactions with humans.
Description
The lesser bulldog bat is a sexually dimoprhic species with males significantly larger than females and with a more pronounced sagittal crest. Furthermore, coloration varies between individuals among the same sex, and between different populations. The bats plump lips and chin that has well-developed cross ridges give rise to the bats "bulldog-like" appearance. N. albiventris roost in caves, rock crevices, buildings, and tree holes. They tend to choose roosts close to water bodies. They are found in Argentina, Belize, Bolivia, Brazil, Costa Rica, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Paraguay, and Peru.
Feeding
The lesser bulldog bat predominantly feed on insects, but they are also known to consume tree pollen, fruit and fish.
Multiple hunting strategies have been observed. Individuals catch insects in flight above both terrestrial and aquatic habitats through aerial hawking. Some bats have also been seen to engage in pointed dips from high or low search flight to snatch prey using their enlarged hind feet or tail membranes.
Lesser bulldog bats are known to forage in groups. Individuals that emerge from their roost together forage together, and they are able to distinguish between their roost mates and other lesser bulldog bats that may be foraging in the same area.
Echolocation
The lesser bulldog bat uses echolocation for foraging, navigation, and social communication. Juvenile bats initially emit only frequency modulation (FM) signals and later learn to produce additional pulse types including quasi-constant frequency (qCF) and combined CF-FM pulses. CF-FM signals consist of a narrowband constant frequency component followed by a broadband frequency-modulated sweep which enhances target detection and spatial resolution. These context-dependent changes allow lesser bulldog bats to hunt more efficiently when foraging in groups. A specific call structure change, for instance, can indicate an insect swarm and its detection distance.
While flying low over water surfaces, the bats emit echolocation calls and detect prey by interpreting returned echoes. Prey items generate acoustic disturbances over reflective backgrounds, allowing the bat to orient towards them. A similar mechanism is used for navigating complex areas.
Development and lifespan
Lesser bulldog bats are seasonally reproductive, with breeding occurring primarily in late November and December. The great rufous woodcreeper has been documented invading roost sites and preying upon individuals by pecking them with their sharp beaks.
Human Impact
Urban noise may influence the behaviour of the lesser bulldog bat. Traffic noise can alter foraging activity and echolocation signals, which may interfere with prey detection in noisy environments.