Habitat-related microgeographic body size variation in two Mediterranean populations of red fox (Vulpes vulpes)

The habitat-related microgeographical body size variations in red foxes Vul pes vulpes living in two separated areas of Mediterranean Spain, the Centra l Ebro Valley (CEV) and Donana National Park (DNP) are analysed. In both ar eas, samples taken from good and bad fox-habitats were compared regarding b ody weight and head and body length. In the Ebro Valley, foxes collected in the good habitat were heavier (14%, P < 0.001 for males; 9%, P < 0.01 for females) and larger (4%, P < 0.01 for males; 1%, P < 0.05 for females) than those collected in the bad habitat. In Donana, males from the good habitat were 19% heavier (P < 0.01) and 3% longer (P < 0.05) than those from the p oorer one. The average weight and size of DNP vixens did not show significa nt differences, although both are higher in the good habitat. It is shown t hat body size of adult foxes can vary, linked to habitat change even across short geographic distances. Some tentative explanations for these results are discussed.