VARIATION IN THE BODY-SIZE OF THE RED FOX

Foxes were measured in a small (75 by 52 km) area of Central Italy. Ma les were larger and heavier than females, while age variation was unsi gnificant. Males were both longer and heavier in the northern than in the southern part of the study area, whereas females were slightly lon ger, but not heavier in the north than in the south. The difference ca nnot be attributed to either cooler climate or larger food supply, and may be related to lower population density. Body mass, head and body length, and tail length are sufficient to separate fox populations stu died worldwide in three clusters corresponding to geographical origin (North American, British, and Continental European). External morpholo gy appears therefore to reflect phylogenetic distance more than global ecological conditions.