Observations on variation in skull size of three mammals in Israel during the 20th century

Abstract

Among mammals, food availability, especially during the growth period, is a key predictor in determining final body size, and improved nutrition may lead to an increase in their body size. In Israel during the last century food availability for animals commensal with humans increased greatly, due to a 16-fold increase in the human population and the accompanying changes, such as a 135-fold increase in the area of irrigated agriculture and the availability of large quantities of organic garbage.Using museum material, we studied temporal changes in skull size of a sample of 89 red foxes (Vulpes vulpes Linnaeus, 1758), 108 golden jackals (Canis aureus Linnaeus, 1758) and 117 Cape hares (Lepus capensis Linnaeus, 1758) collected during the 20th century. Four measurements (condylobasal length, zygomatic breadth, the length of the upper cheek teeth row and the length of the mandible) were taken for each skull, and principal component analysis was used to combine the measurements into principal components.We found that skull size of the red fox increased significantly during the 20th century, possibly due to improved food availability from man-made resources such as agricultural produce and garbage. No temporal trend in body size was detected for the jackal and hare. These differences are discussed.