Molossus rufus, E. Geoffroy Saint-Hilaire, 1805

Don E. Wilson & Russell A. Mittermeier, 2019, Molossidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 598-672 : 626-627

19.

Black Mastiff Bat

Molossus rufus

French: Grand Molosse / German: Rote Samtfledermaus / Spanish: Moloso rufo

Other common names: Black Free-tailed Bat

Taxonomy. Molossus rufus E. Geoffroy Saint-Hilaire, 1805 ,

“Amérique du nord, de Surinam, et principal ement de Caienne [= North America, Suriname, and chiefly form Cayenne].” Restricted by G. S. Miller, Jr. in 1913 to Cayenne, French Guiana.

This species is monotypic.

Distribution. Mexico through Central America into South America to N Argentina and NW Uruguay; also on Trinidad I.

Descriptive notes. Head-body 73-107 mm, tail 40-57 mm, ear 14-19 mm, hindfoot 8-16 mm, forearm 46-55 mm; weight 21-45 g. The Black Mastiff Batis the largest species of Molossus . Dorsal hairs vary from black to red, brown, and yellowish. Dorsal hairs are short (c.2-3 mm), without or with very thin pale band at base, not covering more than one-quarter the hair length. Ventral pelage is paler than dorsal pelage. Ears are rounded and arise from same point on forehead. Tragus is small, and antitragusis constricted at its base. Face, wings, and uropatagium are dark brown or black. Upperlip and snout are smooth and lack any medial ridge. Skull has globose braincase, quadrangular occipital region, and infraorbital foramen opening laterally in frontal view. Basioccipital pits are moderately deep. I* is spatulated, with convergent tips. Chromosomal complement has 2n = 48 and FN = 66.

Habitat. Tropical dry forests, subtropical rainforests, xeric thorn forests, savannas, cerrado, evergreen forests, shrubs, oak forests, and secondary vegetation from sea level up to elevations of ¢. 1500 m.

Food and Feeding. The Black Mastiff Bat is an aerial insectivore that mostly eats Coleoptera , but Chalcidoidea, Diptera , Lepidoptera , Hymenoptera, Odonata , Orthoptera , and Zygoptera have also been found in its feces.

Breeding. Seasonal reproductive synchronization has been suggested for the Black Mastiff Bat, with females in the same population being pregnant at the same time. In south-eastern Brazil, pregnant females were captured in February and September— November, lactating females in August and October-February, and juveniles in January—February. Males seem to be reproductively active year-round. In Yucatan, Mexico, pregnant females have been observed in March—June.

Activity patterns. Activity of the Black Mastiff Bat varies throughout the year. During winter,it leaves roosts during sunset, and the colony stays active for the first 2-3 hours after dusk. During summer, activity starts minutes before sunset. A second peak of activity during dawn was only observed in June and October. Individual activity lasts 26-8-50-5 minutes depending on geographical area, rainfall, wind intensity, food availability, and time of year. Individuals leave their roosts in groups and usually return alone. They roost in buildings, hollow trees, hollow logs, rock crevices, and palm fronds. Search calls have alternate high and low frequency pulses. First pulse has lower peak frequency (22-27 kHz), and second pulse has slightly higher frequency (25-28 kHz).

Movements, Home range and Social organization. The Black Mastiff Bat roosts in large groups of 30-500 individuals, depending on the time of the year. Large colonies are more common during the reproductive period, declining in number during autumn and winter due to dispersal. Sex ratio in groups also changes during the year, and it has been suggested that there is sexual segregation, with males and females in different roosts or in different parts of the same roost, except during the reproductive period. Males are more abundant in roosts in April-July. Number of females increases in July-November and then decreases again during cooler months. During the reproductive period, colonies are formed by similar numbers of males and females, suggesting multi-female-multi-male polygynous behavior. Individuals will return to the same colony for at least three years. The Black Mastiff Bat was also observed roosting with congeners such as Pallas’s Mastiff Bat ( Molossus molossus ), Alvarez’s Mastiff Bat ( M. alvarezi ), and the Coiban Mastiff Bat ( M. coibensis ) and species from other families such as the Greater Spear-nosed Bat (Phyllostomus hastatus).

Status and Conservation. Classified as Least Concern on The [UCN Red Lust.

Bibliography. Anderson (1997), Bowles (1972), Bowles et al. (1990), Dolan (1989), Eger (2008), Esbérard (2002, 2011), Esbérard et al. (2003), Fenton, Rautenbach et al. (1998), Fleming et al. (1972), Freeman (1979), Handley (1976), Howell & Burch (1974), Jones, Smith &Turner (1971), Jung et al. (2014), Leite-Silva et al. (2003), Loureiro, Gregorin & Perini (2018), MacSwiney et al. (2008), Marques-Aguiar (1986), McCracken & Wilkinson (2000), Miller (1913a), Mora (2016), Owen & Girén (2012), Pimenta et al. (2014), Pine (1969), Santos & Castro-Arellano (2006b), Simmons (2005), Timm & LaVal (1998).

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. Mexico through Central America into South America to N Argentina and NW Uruguay ; also on Trinidad I.