Space and time distribution along a succesional gradient of coprofagous coleopterans (Scarabaeinae, Aphodiinae) in a tropical montane forest, Narino Colombia

Dung beetles (Scarabaeinae y Aphodiinae) were used to evaluate the effects of human activities in the area surrounding La Planada Natural Reserve, sou thwestern Colombia. During 1993 we monitored three habitats: primary and se condary forest, and open fields used for cattle grazing. A total of 55 295 trap / hours, evenly distributed among the three habitat types, captured 9 115 individuals (18 species, 11 general. There were differences in species richness between habitats (F-2,F-9 = 29.88; P < 0.001), an in number of ind ividuals (F-2,F-9 = 36.22; P < 0.001). Collecting sites differed within hab itats. Cluster analyses show that species composition differs between habit ats with and without tree cover. Open areas act as barriers for movements o f forest species. Differences between habitats and collecting sites may ref lect high environmental heterogeneity, land use history of the sites or the influence of nearby disturbance. Some of the species found in open fields come from lower elevations and are usually associated with intense human di sturbance. The proportion of digging and rolling: species is similar in bot h primary and secondary forest, nocturnal species are more abundant; in ope n areas rolling species are absent and the number of diurnal species increa ses. We found no relationship between rainfall and species richness (r(2) = 0.26; P = 0.41), nor between rainfall and number of individuals collected throughout the year (r(2) = 0.07; P = 0.84). For all species the number of individuals collected decreased during dry season and during the onset of t he rainy season.