Diet composition of the invasive raccoon dog (Nyctereutes procyonoides) and the native red fox (Vulpes vulpes) in north-east Germany

Abstract

Carcasses of red foxes (n=256) and raccoon dogs (n=253) were collected throughout Mecklenburg Western-Pomerania (north-east Germany) between August 2004 and January 2007. Frequency of occurrence (FO) and biomass share (BS) were estimated for fifteen and seven food categories, respectively. Diet analyses indicate that both canids are omnivorous and pursue opportunistic feeding strategies. Small mammals (BS=31.2, FO=38.7) and vegetable matter (BS=51.3, FO=63.1) were the most important food resources for red foxes and raccoon dogs, respectively. Interspecies differences were recorded for vegetable matter, small mammals and insects. While red foxes mostly feed on voles, raccoon dogs consumed mice and shrews as often as voles. However, unlike red foxes, raccoon dogs did not use small mammals intensively all year round. Only raccoon dogs preyed on amphibians. There were no differences in carrion consumption between red foxes (BS=21.2) and raccoon dogs (BS=18.2). Both red foxes (FO=8.4) and raccoon dogs (FO=8.0) scavenged on wild boar. Moreover, there was evidence that two red foxes foraged on raccoon dogs and vice versa . Mean annual interspecies diet overlap indices were high. We found clear competition for carrion year-round. The diets determined for raccoon dogs and red foxes were quite similar and a similar food niche breadth was recorded. However, only minor competition is assumed to take place since differences in feeding habits do exist. Download the complete issue.