The search for patterns of community structure and composition is essential to provide information which allows the sustained management of species populations and
monitoring of antropic activities. Despite the fact that Neotropical region harbors an enormous diversity of species and complex ecological interactions, very little information is available on snake assemblages. Therefore, the processes responsible for
community organization are not well understood. In Brazil, several studies were
conducted to analyze the factors responsible for the patterns of distribution and
interactions among snake species. In order to identify the factors that determine those
patterns and which affinities (ecological and or historical) those species share, a study of
the local taxocenose of snakes was performed in the Floresta Nacional de Caxiuanã and
adjacent areas, from 2005 to 2006. Four sampling methods were used employed: time
constrained search, local collectors, incidental encounters, and pitfall traps with drift
fences, in five areas (IBAMA and Caquajó in the Floresta Nacional de Caxiuanã;
Marinaú, Enseada and Mojuá located in adjacent areas to the Floresta Nacional de
Caxiuanã). A total of 378 specimens of snakes within five families, 35 genera and 50
species were registered. Considering the records of species obtained in this study and
those from previous studies, the local number of snake species increases from 63 to 69
species. The methods that best revealed the number of individuals were time
constrained search (199/378) and local collectors (159/378). Incidental encounters
(11/378) and pitfall traps with drift fences (9/378) were less representative. The
estimated richness (Jackknife 1) from PLT data was 56 (+or– 4) species. The
composition of snake species in the studied area shows higher similarity with
taxocenoses of other Amazon areas. Most abundant species, as revealed by time
constrained searches, were Imantodes cenchoa, Corallus hortulanus and Leptodeira
annulata. All methods showed Bothrops atrox, Imantodes cenchoa and Corallus
hortulanus as most representative. The areas under high antropic pressures located out
of the National Forest showed lower abundance and richness when compared to
protected areas in there. Nine potentially specialist species were recorded: Lachesis
muta (small mammals), Atractus schach (earthworms), Dipsas catesbyi (mollusks),
Helicops trivitatus and Hydrops triangularis (fish), Siphlophis compressus (lizards),
Xenopholis scalaris, Taeniophallus brevirostris (anuran) and Tantilla melanocephala
(centipedes). The items most frequently consumed were lizards, anurans and small
mammals. The snake species primary or exclusively diurnal represent the larger
percentage. Most species analyzed present non seasonal reproductive period, possibly as
a result of no significant differences in the mean temperature throughout the year. The
taxocenose of snake species in the Floresta Nacional de Caxiuanã and neighboring areas
is formed by groups of species that share similar patterns of feeding and daily activities.
Besides several ecological factors such as temperature and pluviometric averages and
biome structure, historical factors (such as morphological adaptations of snake species)
influence on sbake taxocenose composition in the Floresta Nacional de Caxiuanã and
adjacent areas. Thus, more studies on the ecology and natural history of snakes must be
continuously conducted in order to characterize novel patterns of distribution of snake
species in different biomes.
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