Decline of roller dung beetle (Scarabaeinae) populations in the Iberian peninsula during the 20th century

A historical compilation of data on roller dung beetle occurrence in the Iberian peninsula was examined for temporal changes between the first and second half of the 20th century. Analysis of changes in the relative frequency of database records, individuals and 10-km UTM cells where the beetles occurred showed a decline in the occurrence of nine of the eleven species. A comparison of latitudinal and longitudinal mid-points of the 10-km UTM cells where each species occurs indicated that the range of most roller dung beetles in the Iberian peninsula has also contracted. Before 1950 a significant, positive and curvilinear relationship was found between the number of roller dung beetles and the area of coastal environments (sea, dunes, beaches and marshes); while in the second half of the 20th century the number of “roller” species is positively correlated with artificial pastureland and scrub areas. It is suggested that urban development of the coastal zones for tourism since 1950 has probably contributed greatly to the disappearance of many roller populations. It is recommended that some of the more affected species of roller dung beetles should be considered for inclusion among protected invertebrates.