Diel flight activity and ecological segregation within an assemblage of tropical forest dung and carrion beetles

Temporal variation in activity of dung and carrion beetles in tropical forest is considered as a mechanism of ecological segregation between potentially competing species. We describe the diel flight activity of Scarabaeidae collected with baited pitfall traps at Les Nouragues field station in French Guiana. A total of 2663 individuals of 63 species was recorded, from the subfamilies Coprinae, Scarabaeinae and Aphodinae. Temporal guilds of diurnal, nocturnal and crepuscular species were identified. Diurnal species were about twice as numerous and abundant as either nocturnal or crepuscular species. Two main activity patterns characterize the diurnal species while nocturnal and crepuscular species show overlapping activity. The association of activity rhythm with the other niche variables, food selection, functional group, body size and relative abundance, was analysed using multiple correspondence analysis. Small diurnal coprophagous species were opposed to large crepuscular necrophagous species. Species packing is suggested but further analysis showed that the variables were independent of one another. The temporal differentiation of species combined with separation along multiple niche dimensions and resource gradients may facilitate the coexistence of species assumed to be strongly affected by interspecific competition.