Rousettus obliviosus, Kock, 1978

Don E. Wilson & Russell A. Mittermeier, 2019, Pteropodidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 16-162 : 88-89

48.

Comoro Rousette

Rousettus obliviosus

French: Roussette des Comores / German: Komoren-Flughund / Spanish: Rosetus de las Comoras

Other common names: Comoros Rousette

Taxonomy. Rousettus obliviosus Kock, 1978 ,

near Bomboni, 640 m, Grand Comore, Comoro Islands.

Rousettus obliviosus is not a subspecies of R. madagascariensis as once thought; genetic studies have shown a clear separation between the two. Monotypic.

Distribution. Comoros Is (Grande Comore, Mohéli, and Anjouan).

Descriptive notes. Head-body 121- 142 mm, tail 14-25 mm, ear 15-18 mm, hindfoot 13-17 mm, forearm 70-78 mm; weight 42-73 g. The Comoro Rousette is smaller than the Egyptian Rousette ( R. aegyptiacus ) and similar in size to the Malagasy Rousette ( R. madagascariensis ), but it has a more robust skull and strongly deflected braincase, with alveolar line projected backward passing through occiput above foramen magnum. Fur color is dull gray-brown, and dorsal side oftibia is naked. Postorbital width is usually larger than interorbital width, supra-occipital crest is well developed, and premaxillae are not co-ossified. Palatal ridge pattern is normally 4 + 3 + 1. Cheekteeth have typical rousettine proportions, and P' is relatively large.

Habitat. Widely distributed in now limited tropical moist forest and agricultural land from sea level up to elevations of ¢. 1750 m. Comoro Rousettes are very tolerant of human-dominated landscapes.

Food and Feeding. Fruits have been identified as food sources of the Comoro Rousette based on regurgitated pellets, including Ficus (Moraceae) , Gambeya ( Sapotaceae ), Anthocleista grandiflora (Gentianaceae) , and introduced species such as papaya ( Carica papaya, Caricaceae ), jackfruit ( Artocarpus integrifolia, Moraceae ), banana ( Musa spp. , Musaceae ), and Ceiba pentandra ( Malvaceae ). They also use flowers inferred by pollen on facial fur and visits to flowering plants. Use of leaves was inferred from small pellets. Comoro Rousettes forage in agricultural fields, degraded or intact forests, and understory plantations.

Breeding. Lactating and pregnant Comoro Rousettes were captured in July, and nonreproductive young were captured in July-August on Anjouan. Pregnant and lactating females and reproductive males were captured in November on Grande Comore. Based on these observations, the Comoro Rousette probably is seasonally monoestrous, with reproduction in wet seasons (October—April).

Activity patterns. Comoro Rousettes are strictly nocturnal, usually leaving roostsites around sunset and circling outside rock shelters before departing in large swarms. They return to caves gradually, swarming and circling entrances until sunrise. They have been seen flying above, at, or below canopy levels. They are very maneuverable and can hover briefly. They roost in caves formed by lava tubes and rock shelters (shallow caves), overhanging above watercourses and cascades. Caves are occupied beyond twilight zones, up to 150 m from entrances. Roost sites were found in densely forested, isolated areas on Mohéli and in large caves surrounded by agricultural fields on Grande Comore, although cave entrances were always covered by thick vegetation.

Movements, Home range and Social organization. Comoro Rousettes cluster in small (50 individuals) to large colonies (3000-4000 individuals). A genetic study based on cytochrome-b and six microsatellite loci showed no interisland genetic structure, indicating that distances of 40-80 km between Comoros Islands are not enough to stop dispersal of Comoro Rousettes across islands. Nevertheless, they are absent from Mayotte probably because of lack of adequate roosting sites.

Status and Conservation. Classified as Vulnerable on The IUCN Red List. Conservation status of the Comoro Rousette is due to scarcity of roosts, physical instability of caves, and rapid deforestation in the Comoros Islands in recent years, despite its adaptability to disturbed habitat. The Comoro Rousette receives the highest level of legal protection available in the Union of the Comoros. It was listed as an “integrally-protected species” in 2001, which prohibits capture or detention of individuals without a permit. The national Conservation Action Plan for Livingstone’s Flying Fox ( Pteropus livingstonit), another threatened pteropodid from Comoros, includes an appendix with recommendations for conservation of the Comoro Rousette. These recommendations focus on protection of roost caves, discouraging hunting through environmental education, and population monitoring.

Bibliography. Bergmans (1994), Goodman, Chan et al. (2010), Goodman, Weyeneth et al. (2010), Sewall (2016), Sewall et al. (2003).

Figures

32. Zenker’s Fruit Bat (Scotonycteris zenkeri), 33. Hayman’s Fruit Bat (Scotonycteris occidentalis), 34. Bergmans’s Fruit Bat (Scotonycteris bergmansi), 35. Short-palated Fruit Bat (Casinycteris argynnas), 36. Pohle’s Fruit Bat (Casinycteris ophiodon), 37. Campo-Ma’an Fruit Bat (Casinycteris campomaanensis), 38. Lesser Dawn Bat (Eonycteris spelaea), 39. Greater Dawn Bat (Eonycteris major), 40. Philippine Dawn Bat (Eonycteris robusta), 41. Geoffroy’s Rousette (Rousettus amplexicaudatus), 42. Bare-backed Rousette (Rousettus spinalatus), 43. Leschenault’s Rousette (Rousettus leschenaultin), 44. Linduan Rousette (Rousettus linduensis), 45. Sulawesi Rousette (Rousettus celebensis), 46. Egyptian Rousette (Rousettus aegyptiacus), 47. Malagasy Rousette (Rousettus madagascariensis), 48. Comoro Rousette (Rousettus obliviosus), 49. Long-haired Fruit Bat (Stenonycteris lanosus)

Distribution. Comoros Is (Grande Comore, Mohéli, and Anjouan).