Tonatia bidens (Spix, 1823)

Don E. Wilson & Russell A. Mittermeier, 2019, Phyllostomidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 444-583 : 505

36.

Greater Round-eared Bat

Tonatia bidens

French: Tonatia de Spix / German: GroRe Rundohrblattnase / Spanish: Tonatia grande

Other common names: Spix's Round-eared Bat

Taxonomy. Vampyrus bidens Spix, 1823 ,

“fluvium St. Francisci” (= Rio Sao Francisco), Bahia, Brazil.

J. E. Gray in 1827 proposed bidens as the type species of Tonatia . A similar bat, Phyllostoma childreni, was later described also from South America. Eventually, both names were synonymized under Lophostoma bidens . After some nomenclatural changes, S. L. Williams and colleagues in 1995 used quantitative and qualitative analyses of morphological traits and restricted 7. bidens to the southernmost South American populations ( Brazil, Paraguay, and Argentina) and 7. saurophila to the north-western and central populations. Thus, literature on 7. bidens in Central America and northern South America, including the Guyana Shield and Venezuela, refers to 1. saurophila . Monotypic.

Distribution. E Brazil, E Bolivia, Paraguay, and N Argentina.

Descriptive notes. Head-body 69-81 mm, tail 16-19-5 mm, ear 22-30 mm, hindfoot 12-18 mm, forearm 48-8-59-3 mm; weight 27-34 g. Greater lengths of skulls are 26-6— 29-5 mm. Some sexual dimorphism in body size with males averaging slightly larger. The Greater Round-eared Bat is medium-sized and long-eared, with well-developed noseleaf and short tail completely embedded in uropatagium or slightly protruded from it. Dorsal fur varies from brown through blackish brown, with whitish hair tips. Ventral pelage is brown, always paler than dorsal pelage. Proximal one-half of forearm is densely haired. Rostrum, ears, forearms, legs, and feet are furred. Its large ears are notjoined by band ofskin across forehead. It has central wart on lowerlip, surrounded by numerous small warts. Skull is large and robust, with broad rostrum. I is weakly bilobed. The Greater Round-eared Bat can be differentiated from its congener, the Stripe-headed Round-eared Bat ( 7. saurophila ), by broader postorbital constriction (greater than 5-4 mm), shorter ears (less than 30 mm), less developed sagittal crest, and absence of pale stripe of fur between ears. Its sparsely furred muzzle distinguishes it from very similar round-eared bats ( Lophostoma ) that have naked muzzles. Dental formula for all species of Tonatiais12/1,C1/1,P 2/3, M 3/3 (x2) = 32.

Habitat. Dry and shrub forests (restinga) on coastal plain, primary and secondary Atlantic forests (“Mata Atlantica”), tropical savannas (cerrado), Pantanal wetlands, and desert vegetation consisting of xeric shrubland and thorn forest (caatinga habitat) in Brazil and dry forests, chaparrals, streamside forests, and forest edges near agricultural areas in Paraguay and Argentina, more abundant at elevations less than 100 m. Greater Round-eared Bats apparently prefer more open habitat for foraging due to better maneuvering and greater exposure of potential prey.

Food and Feeding. The Greater Round-eared Bat is a foliage-gleaning omnivore, preferring large insects, small birds, and fruit. Insect remains are most frequently found in shelters and include a wide variety of groups such as Lepidoptera , Orthoptera , Coleoptera , Hemiptera , Odonata , Thysanoptera , and Blattodea . In Brazil, its diet was assessed by direct observations of individuals feeding in shelters, by collecting prey remains from feeding roosts, and by analyzing stomach contents.It fed intensively on small birds (4-24 g), size being the main factor determining prey selection. About 30 species of birds were identified as prey, mostly passerines that were abundant during rainy seasons compared with dry seasons when insects were more common in diets. It occasionally also fed on amphibians and reptiles. Captive Greater Round-eared Bats capture prey and immobilizes it with a bite on the neck, head, or abdomen; prey is then surrounded with wings, aided by thumbs for immobilization.

Breeding. The Greater Round-eared Batis seasonally polyestrous and has a bimodal pattern, with first peak of births in rainy season. In Brazil, pregnant females have been found in November—January and lactating females in January and April-May. Males with visible testicles (scrotal) were found in January, March-May, June, September, and November—December. It forms harems with one male and up to c.12 females and their young in shelters.:

Activity patterns. The Greater Round-eared Bat is nocturnal, mainly crepuscular, with predominant activity during first hours after sunset until a few hours before dawn. Roosts have been found in tree cavities, human dwellings (e.g. abandoned houses), and caves. These shelters probably offer stable and secure environment to establish permanent or semi-permanent roosts, and there are indications of some degree of roost fidelity.

Movements, Home range and Social organization. The Greater Round-eared Bat apparently occurs in low densities throughoutits distribution. In the state of Rio de Janeiro, Brazil, a colony of Greater Round-eared Bats was found in a palm tree hollow 7 m aboveground. The colony had one male and three reproductive females and shared the roost with Seba’s Short-tailed Bats ( Carollia perspicillata ) and Common Vampire Bats ( Desmodus rotundus ). In another locality, a group of Greater Round-eared Bats cohabited a water mine with White-throated Round-eared Bats ( Lophostoma silvicola ).

Status and Conservation. Classified as Data Deficient on The IUCN Red List.

Bibliography. Carter & Dolan (1978), Emmons & Feer (1997), Esbérard & Bergallo (2004), Gardner (1977b), Gray (1827), Martuscelli (1995), Paca et al. (2012), Smith (2009, 2012), Smith et al. (2012), Spix (1823), Williams & Genoways (2008), Williams et al. (1995), Willig (1985a).

Figures

24. Long-legged Bat (Macrophyllum macrophyllum), 25. Fringe-lipped Bat (Trachops cirrhosus), 26. Striped Hairy-nosed Bat (Gardnerycteris crenulatum), 27. Keenan's Hairy-nosed Bat (Gardnerycteris keenani), 28. Koepcke’s Hairy-nosed Bat (Gardnerycteris koepckeae), 29. Kalko’s Round-eared Bat (Lophostoma kalkoae), 30. Pygmy Round-eared Bat (Lophostoma brasiliense), 31. Carriker’s Round-eared Bat (Lophostoma carrikeri), 32. Schulz’s Round-eared Bat (Lophostoma schulzi), 33. Western Round-eared Bat (Lophostoma occidentale), 34. Davis's Round-eared Bat (Lophostoma evotis), 35. White-throated Round-eared Bat (Lophostoma silvicola), 36. Greater Round-eared Bat (Tonatia bidens), 37. Stripe-headed Round-eared Bat (Tonatia saurophila), 38. Pale-faced Bat (Phylloderma stenops), 39. Pale Spear-nosed Bat (Phyllostomus discolor), 40. Lesser Spear-nosed Bat (Phyllostomus elongatus), 41. Greater Spear-nosed Bat (Phyllostomus hastatus), 42. Guianan Spear-nosed Bat (Phyllostomus latifolius), 43. Woolly False Vampire Bat (Chrotopterus auritus), 44. Southern Golden Bat (Mimon bennettii), 45. Cozumelan Golden Bat (Mimon cozumelae), 46. Spectral Bat (Vampyrum spectrum)

Distribution. E Brazil , E Bolivia , Paraguay , and N Argentina .