Pallas’s Mastiff Bat: Molossus Molossus

Image of Pallas’s Mastiff Bat

The Pallas’s Mastiff Bat is a non-migratory species but moves roosts seasonally. It is typically found in Cuba and could have naturally dispersed there. This species of bat is known to be an aerial-hawking insectivore.

Learn More: Rare Bat In The U.S.

Description Of The Pallas’s Mastiff Bat

The Mastiff Bat of Pallas (Molossus molossus fortis), also known as Velvety Free-tailed Bat and House Bat, belongs to the Order Chiroptera; Family Molossidae; Genus Molussus; a small genus with less than 20 known species.

Members of this family have tails that extend well beyond the tail membrane’s edge. They all have short, dense fur, and they emit a musky smell. Molossidae bats range from Mexico to Argentina, including the Florida Keys and the Caribbean Islands.

Molossus molossus fortis is a medium-sized bat with a weight of just 15 grams, a forearm measuring 59 to 61 millimeters, and very long and narrow high aspect ratio wings that facilitate fast and efficient flight. In order to achieve lift, their long and narrow wings require them to gain speed before flight; before they extend their wings, they must drop vertically from their perch.

The reddish-brown to black fur of Molossus molussus has a tail that protrudes free of the tail membrane. Although the Pallas’ mastiff bat’s appearance is similar to the Mexican free-tailed bat (Tadarida brasiliensis), it has different ears that lie forward and are joined at the base. 1Go To Source -“Velvety Free-Tailed Bat”

Pallas’s Mastiff Bat Behavior

This species will forage during the night year-round. It usually goes into daily torpor from Activity usually resumes every night for feeding, except when temperatures drop below 41 ° F, from December to February.

The range of nocturnal foraging may exceed 24 km from roost locations. This bat seldom uses night roosts. This bat has an exceptionally long period of foraging, up to 6-7 hours a night.

The Pallas’s Mastiff Bat is a non-migratory species but moves roosts seasonally. It moves between alternate roosts in the daytime. 2Go To Source -“California Wildlife Habitat Relationships System”

Mastiff Bat Reproduction

Females give birth to one pup, but they may have more than one reproductive cycle in one year. Babies are born from June through September during the summer. 3Go To Source -“Velvety free-tailed bat”

Diet Of Pallas’s Mastiff Bats

Very little has been reported in academic research about the food patterns of the Pallas’s Mastiff Bat. This species of bat is known to be an aerial-hawking insectivore. There are no reports on this species’ diet; however, it is possible that the diet closely resembles that of the species of Molossus.

Its believed that prey range in size from 2-25 mm and includes a wide range of insects. Both the Pallas’ mastiff bat and the black mastiff bat’s stomach contents included: 4Go To Source -“Promops nasutus brown mastiff bat”

  • Bees, Ants, And Wasps
  • Damselflies
  • Real bugs
  • Real flies
  • Beetles
  • Grasshoppers

Pallas’s Mastiff Bat Habitat

Velvety free-tailed bats are known to roost (sleep during the day) only in human-made structures in the United States. In groups of as many as 1,300 individuals, they have been found roosting in attics, crawl spaces, crevices, and under eaves. They roost in tree hollows and in holes in utility poles in Cuba as well.

These bats emerge earlier than most other bats, often shortly before sunset, from their roosts. At high altitudes, they feed on insects. Their big, forward-facing ears are believed to be aerodynamically aligned to conserve energy during flight. 5Go To Source -“Florida’s Bats: Velvety Free-Tailed Bat”

Range Of The Pallas’s Mastiff Bat

The Pallas’s mastiff bat species is typically found in Cuba and could have naturally dispersed there, but it was also introduced in 1929 at the Perky Bat Tower on Sugarloaf Key as part of the mosquito control effort.

Currently, only in areas near the alleged release site have these bats been found. Although these bats roost in buildings, when feeding, they range across a variety of habitats. Most recently, colonies have been found on Vaca Key, Stock Island, and Boca Chica Key. 6Go To Source -“Pallas’s mastiff bat (Molussus molussus tropidorhynchus)”



  1. Mowbray, Alan. “El Yunque National Forest – Nature & Science.” United States Department of Agriculture Forest Service, USDA, Accessed 12 Jan. 2021.
  2. Ahlborn, G. “California Wildlife Habitat Relationships System California Department of Fish and Wildlife California Interagency Wildlife Task Group.” California Department Of Fish And Wildlife, State of California, Accessed 12 Jan. 2021.
  3. “Velvety Free-Tailed Bat.” Florida Bat Conservancy, Florida Bat Center, Accessed 12 Jan. 2021.
  4. Fox, A. 2018. “Promops nasutus” (On-line), Animal Diversity Web. Accessed January 12, 2021 at
  5. Ober, Holly, et al. “Florida’s Bats: Velvety Free-Tailed Bat.” University Of Florida IFAS Extension, Department of Wildlife Ecology and Conservation, Oct. 2016,,in%20holes%20in%20utility%20poles.
  6. —. “Pallas’s Mastiff Bat (Molussus Molussus Tropidorhynchus).” Florida Fish And Wildlife Conservation Commission, Accessed 12 Jan. 2021.