| ARBOREAL HABITS AND VIPER BIOLOGY IN THE AFRICANRAINFOREST: THE ECOLOGY OF ATHERIS SQUAMIGER |
LUCA LUISELLI A1, FRANCESCO M. ANGELICI A1, LUCA LUISELLI A2, FRANCESCO M. ANGELICI A2, GODFREY C. AKANI A2
A1 Environmental Studies Institute DEMETRA and F.I.Z.V. via dei Cochi 48/B, I-00133 Rome, Italy and Municipal Natural History Museum, piazza Aristide Frezza 6, I-00030 Capranica Prenestina, Rome, Italy
A2 Department of Biological Sciences, The Rivers State University of Science and, Technology, P.M.B. 5080, Port Harcourt, Rivers State, Nigeria
Aspects of the ecology of the arboreal viper Atheris squamiger are studied. A. squamiger is common in southeastern Nigeria, where it was observed mainly in secondary forest patches (both dry and flooded) and in shrublands, and frequently also in primary forest patches. Conversely, it was rarely found in strongly altered habitats (farmlands, plantations, and suburbs). Adult sex ratio was nearly equal, and the proportion of immatures in the examined sample did not differ significantly between sexes. The two sexes attained similar mean sizes, but females had modal and median lengths higher than males. Maximum male length was 67.0 cm, and maximum female length was70.5 cm. Juveniles contained food in the gut much more frequently than the adults. A. squamiger fed primarily upon small mammals, and much more rarely upon scincid lizards and birds. No frogs were taken. There was an ontogenetic shift in taxonomical dietary preferences, with juveniles taking not only endothermic but also ectothermic prey (lizards), and adults also taking birds but not reptiles. Moreover, among the mammals eaten, shrews were dominant in juveniles, whereas rodents were dominant in adults. Adults of both sexes were similar in terms of taxonomic dietary composition, but birds were preyed upon slightly more frequently by males. Prey consumed by the vipers were mainly nocturnal, both arboreal and terrestrial. There was a significant positive relationship between predator mass and prey mass. Activity of A. squamiger was highest during the wet season (May to August), very high in the intermediate periods between dry and wet seasons (March to April, and September to October), and very reduced during the dry season (November to February), mainly during the early night hours (from 6 p.m. to 2 a.m.).Vipers were found on the ground more often during the night. Height of perches of vipers on trees averaged 1.9 2.0 m (n = 34) during the day, and0.4 1.1 m (n = 29) during the night.
The references of this article are secured to subscribers.