HERPETOLOGICAL NATURAL HISTORY VOL.6 DECEMBER 1998 Herpetological Natural History, 6(2), 1998, pages 78-150. ©1998 by the International Herpetological Symposium, Inc. NO.2 NATURAL HISTORY OF SNAKES IN FORESTS OF THE MANAUS REGION, CENTRAL AMAZONIA, BRAZIL* Marcio Martins Departamento de Ecologia Geral, Instituto de Biociencias, Universidade de Sao Paulo, Caixa Postal 11.461, 05422-970 Sao Paulo SP, Brazil M. Ermelinda Oliveira Departamento de Parasitologia, Instituto de Ciencias Biol6gicas, Universidade do Amazonas, Av. Rodrigo Otavio 3.000, 69077-000 Manaus AM, Brazil Abstract. We present natural history information on 66 species of snakes found in the forests of the Mana us region, Central Amazonia, Brazil. For each species, we provide information on size, color pattern, habitat and microhabitat, feeding habits, reproduction, and defense. We also include a partial summary of the infor- mation available in the literature for Amazonian localities. Our results are based on nearly 800 captures or sightings of snakes made from 1990-95 at localities around Manaus, mostly at a primary forest reserve 25 km north of Manaus. Field data at this reserve were obtained during over 2600 person-h of visually search- ing for snakes, ca. 1600 of which occurred during time-constrained search. Temperature and relative humid- ity in Manaus are high and the amount of annual rainfall (2075 mm/yr) is relatively small, with a long dry season (4-7 mo). Of the 65 species for which information is available, 28 (42%) are primarily terrestrial, 20 (30%) fossorial and/or cryptozoic, 13 (20%) arboreal, and four (6%) aquatic, although many species use more than one microhabitat when active. Nearly all inactive snakes were found on vegetation. In relation to time of activity, 26 (41 %) of the 62 species for which information is available seem to be strictly diurnal, 13 (21%) strictly nocturnal, and 23 (38%) both diurnal and nocturnal. The five prey types most commonly consumed by snakes in the Manaus region are vertebrates: lizards (consumed by 58% of the species), frogs (39%), mammals (23%), birds (18%), and snakes (16%). A cluster analysis combining data on microhabi- tat usc, die! activity, and diet resulted in several groups of species with similar habits. All these "guilds" included closely related species, as well as distantly related ones that converge in habits. These combined results indicate that in addition to current ecological factors (e.g., predation pressure, differential prey avail- ability in different microhabitats), historical factors (phylogeny and biogeography) may have played an important role in determining the current natural history patterns of this snake assemblage. A high diversity *This study is dedicated to O.R. Cunha and F.P. Nascimento (both now retired from Museu Goeldi, Belem) for their unparalleled contributions to the knowledge of Brazilian Amazonian snakes, including natural history, and the immense collection of snakes at the MPEG, an invaluable source of natural history information for years to come.