Molossus molossus (Pallas, 1766)

Don E. Wilson & Russell A. Mittermeier, 2019, Molossidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 598-672 : 626

17.

Pallas’s Mastiff Bat

Molossus molossus

French: Molosse commun / German: GrolRe Samtfledermaus / Spanish: Moloso comun

Other common names: Pallas’s Free-tailed Bat, Velvety Free-tailed Bat

Taxonomy. Vespertilio molossus Pallas, 1766 ,

America. Restricted by A. M. Husson in 1962 to Martinique, Lesser Antilles.

Recently, two subspecies of M. molossusin the Greater Antilles were recognized as distinct species: M. miller: and M. verrilli . Monotypic.

Distribution. SW USA (Florida), and from NE Mexico (Coahuila), S through Central America into South America to Argentina and Uruguay; also on Puerto Rico and Lesser Antilles.

Descriptive notes. Head-body 54-80 mm, tail 30-46 mm, ear 11-15 mm, hindfoot 7-11 mm, forearm 36-43 mm; weight 9-17 g. Pallas’s Mastiff Bat is overlaps in size with the Aztec Mastiff Bat (M. aztecus ), the Pug-nosed Mastiff Bat (M. miller), and the Hispan-1olan Mastiff Bat ( M. verrilli ). Dorsal hairs of Pallas’s Mastiff Bat are noticeably bicolored, with pale basal band reaching one-quarter to one-half the hair length. Dorsal pelage color is highly variable, ranging from cinnamon to cocoa-brown. Some individuals have very dark pelage, and others (mostly young) are grayish. Ventral pelage is lighter than dorsal pelage. Ears are rounded and arise from same point on forehead. Tragusis small, and antitragus is constricted at its base. Face is medium to dark brown. Upperlip and snout are smooth and lack any medial ridge. Wings and uropatagium are brownish. Skull has elongated braincase, triangular occipital region, and infraorbital foramen opening frontally in frontal view. Basioccipital pits are moderately deep. I? is elongated, with parallel tips, but shape varies among populations, ranging from tapered to moderately wide. Chromosomal complement has 2n = 48 and FN = 64 (north-eastern Brazil), 2n = 48 and FN = 54 (southern Brazil), 2n = 48 and FN = 58 (West Indies and several localities in northern and western South America), and 2n = 48 and FN = 56 ( Puerto Rico).

Habitat. Cerrado, dry and humid semideciduous forests, tropical rainforests, swamps, pastures, evergreen forests, and savannas from lowlands up to elevations of ¢. 1250 m. Pallas’s Mastiff Bat adapts well to anthropogenic modifications, and it has been found in small patches of vegetation and urban areas.

Food and Feeding. Pallas’s Mastiff Bat is an aerial insectivore. Coleoptera , Diptera, Isoptera , Hymenoptera, Homoptera , Lepidoptera, Odonata , Orthoptera , and Hemiptera have been found in its feces.

Breeding. Pallas’s Mastiff Bats reproduce only once or twice in their short life spans (maximum of 5-6 years). In Brazil, pregnant females and young were caught in November and March-April, with only one embryo per pregnancy. This pattern can change depending on geographical location. In Panama, for example, pregnant females were caught in March—-August, and pregnancy peak was observed in April. Females usually give birth during rainy seasons, and males are sexually active throughout the year. Females have been caught simultaneously lactating and pregnant. Lactation lasts c.1-5 months.

Activity patterns. Activity of Pallas’s Mastiff Bat is bimodal, foraging during dawn and dusk with short activity bouts of less than an hour. First peak of activity starts just before sunset and continues for 31-60 minutes. Second peak starts before dawn and continues until a few minutes after sunrise. Individuals from the same colony foraged together significantly more often than they do alone or with individuals from other groups. Pallas’s Mastiff Bat roosts in buildings, hollow trees, and palm leaves. Search calls can vary from shallow FM signals to pulses composed of steeper FM element and shallow FM component. Search calls regularly alternate between two and three tones. First pulse has lower frequency (33-39 kHz) than intermediate pulse with slightly higher frequency (35-45 kHz). Third and higher frequency pulses (40-45 kHz) might or might not occur. Several birds are known to prey on Pallas’s Mastiff Bats: black-andwhite owls (Ciccaba nigrolineata), merlins (Falco columbarius), peregrine falcons (Falco peregrinus), and great kiskadees (Pitangus sulphuratus).

Movements, Home range and Social organization. In Panama, Pallas’s Mastiff Bats form small to intermediate colonies compared with its congeners, varying between one and 32 individuals (mean 9-6 ind/colony). Most groups are composed ofa stable core of adult females, young, and 1-2 adult males. Young of both sexes disperse from their natal group and settle in a new colony. In Brazil, groups with more than 400 individuals have been reported roosting in the same site, and two types of colonies are formed during months of sexual inactivity and reproductive season. Reproductive colony contains a high number of females and their young. Females return to their natal roosts to reproduce and stay in this colony until young are independent. Colonies outside breeding season have higher proportions of males than females and reduced number of individuals compared with colonies during breeding seasons. Individuals stay an average of three months in each of the two colonies. Colonies of Pallas’s Mastiff Bat were found roosting with other species of Molossus , such as Miller's Mastiff Bat ( M. pretiosus ) and the Black Mastiff Bat ( M. rufus ), and species in other families, such as the Lesser Bulldog Bat (Noctilio albiventris), Pallas’s Long-tongued Bat (Glossophaga soricina), and the Common Black Myotis ( Myotis nigricans).

Status and Conservation. Classified as Least Concern on The IUCN Red List. Pallas’s Mastiff Bat has a wide distribution and presumably large populations. It occurs in several protected areas and tolerates some habitat modification.

Bibliography. Baker & Lopez (1970b), Castro-Arellano & Uribe (2014), Chase et al. (1991), Dechmann et al. (2010), Dolan (1989), Eger (2008), Esbérard (2011), Esbérard & Bergallo (2010), Fabian & Gregorin (2007), Fabian & Marques (1989), Freitas et al. (1992), Gager et al. (2016), Howell & Burch (1974), Husson (1962), Ibanez et al. (1992), Krutzsch & Crichton (1985), Leite-Silva et al. (2003), Lépez-Baucells, Rocha, Bobrowiec et al. (2018), Loureiro, Gregorin & Perini (2018), Michael et al. (1993), Mikula et al. (2016), Mora (2016), O'Farrell et al. (1999), Owen & Gir6n (2012), Pimenta et al. (2014), Reid (2009), Surlykke & Kalko (2008), Timm & LaVal (1998), Voigt-Heucke et al. (2010), Warner et al. (1974).

Figures

1. Blunt-eared Bat (Tomopeas ravus), 2. Lesser Naked Bat (Chewromeles parvidens), 3. Greater Naked Bat (Chewromeles torquatus), 4. Peters’s Little Mastff Bat (Mormopterus jugularis), 5. Reunion Little Masuft Bat (Mormopterus francoismoutoui), 6. Mauritian Little Mastiff Bat (Mormopterus acetabulosus), 7. Sumatran Little Mastift Bat (Mormopterus doriae), 8. Least Little Mastiff Bat (Mormopterus minutus), 9. Kalinowski’s Little Mastiff Bat (Mormopterus kalinowskii), 10. Incan Little Masuft Bat (Mormopterus phrudus), 11. Alvarez’s Mastff Bat (Molossus alvarez), 12. Aztec Mastff Bat (Molossus aztecus), 13. Coiban Mastuff Bat (Molossus cotbensis)

Distribution. SW USA (Florida), and from NE Mexico (Coahuila), S through Central America into South America to Argentina and Uruguay ; also on Puerto Rico and Lesser Antilles.