The Impact of Upgrading Roads on the Conservation of the Threatened Flightless Dung Beetle,Circellum bacchus(F.) (Coleoptera: Scarabaeidae)

Abstract

The flightless dung beetle Circellum bacchus (Fabricius, 1781) is a unique, ectothermic dung beetle that is of conservation concern due to a massive decline in its distribution. Very little is known about its conservation ecology and the upgrade of roads in one of its last strongholds, South Africa's Addo Elephant National Park, led to concerns that road kill was threatening the population because drivers could not see the beetles due to their similar colour as the upgraded roads. We tested whether the upgraded, black, tar roads led to more road kills than the original sandy-red, gravel roads using counts of live and dead beetles along transects through similar habitats of the park. There was no significant difference between the number of live and dead dung beetles on the tar or gravel roads illustrating that the infrastructure improvements themselves are not threatening the persistence of the species. The high levels of vehicle-derived mortality along roads, however, suggest that road kills may be a threatening process with potentially 100,000 C. bacchus killed on roads annually (although 45,000 is a more conservative estimate). Further research is needed to ascertain whether this off-take is sustainable and to formulate mitigation measures.