Evol Ecol Res 5: 1037-1048 (2003)     Full PDF if your library subscribes.

Increase of skull size in the red fox (Vulpes vulpes) and Eurasian badger (Meles meles) in Denmark during the twentieth century: an effect of improved diet?

Yoram Yom-Tov,1* Shlomith Yom-Tov1 and Hans Baagøe2

1Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel and  2Zoological Museum, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark

Author to whom all correspondence should be addressed.
e-mail: yomtov@post.tau.ac.il


The skulls of 272 red foxes (Vulpes vulpes) and 308 Eurasian badgers (Meles meles) collected in Denmark over the last 120 years were measured to determine any temporal changes in skull size (and, by implication, body size) during the studied period. We wished to determine whether global warming had resulted in a decrease in skull and body size in accordance with Bergmann’s rule. Contrary to our predictions, there were no significant negative relationships between any of the four skull characters measured and mean annual temperature. Among badgers, two of the four characters measured had increased significantly during the twentieth century (zygomatic breadth by about 2% and length of upper molar by about 3.5%), but only in Jutland. In the red fox, three of the four skull characters measured had increased significantly during the twentieth century (zygomatic breadth by about 5%, length of fourth upper premolar by about 7% and diameter of canine by about 9%), with one parameter (zygomatic breadth) increasing twice as fast in Zealand as in Jutland. All the above three characters are closely associated with diet: the size of the zygomatic arch is closely related to the size of the masseter muscle, the size of the carnassial and the diameter of canine are generally associated with prey size, and the size of the first molar is associated with grinding of grain and larger invertebrates. Larger teeth enable a predator to take and handle larger prey items. However, the fourth parameter (greatest length of skull) had not increased during the studied period. Since all the above skull characters are significantly related to body size, these results indicate that the body size of both species had increased during the twentieth century. The increase in skull characters is probably related to contemporaneous changes in Danish agriculture and land use, which, in turn, resulted in changes to the foxes’ and badgers’ diets.

Keywords: body size, Denmark, diet, Eurasian badger, red fox.

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