Diel separation of Afrotropical dung beetle guilds—avoiding competition and neglecting resources (Coleoptera: Scarabaeoidea)

Dung beetle guilds of different competitive level coexist at high abundances in the forest–savanna mosaic of Ivory Coast. A total of 25 875 specimens was recorded from 90 samples of fresh buffalo dung exposed for 4-h periods over the day in the Parc National de la Comoé. Redundancy analyses show different patterns of the guild structure determined by time of day, and positive correlations of guild abundance with temperature. The competitively superior telecoprids (rollers) have their abundance peak at midday when the high temperatures presumably enable them to perform their energetically costly rolling behaviour at greater speed. The competitively intermediate paracoprids (tunnellers) and the competitively inferior endocoprids (dwellers) have their peak around dusk when: (1) the superior competitors are not active, and (2) they can easily synchronize their flight activity using light intensity changes. During the two peaks of flight activity of the dung beetles, their abundance at the resource is very high, causing obvious competition. On the other hand, the resource is hardly used between 22:00 h and 10:00 h. This is probably due to physiological constraints (high optimum temperature required for the diurnal species and dependence on light intensity patterns as a flight trigger of the nocturnal species, respectively). Shifting flight activity to these periods of low competition does not occur, resulting in a unequal level of competition over the day, thus periods of considerable competition within dung beetle assemblages alternate with vacant temporal refuges.