The high level of nutritional niche overlap between red fox (Vulpes vulpes) and sympatric golden jackal (Canis aureus) affects the body weight of juvenile foxes

In the period of August 2013 to September 2015, we collected and measured the body weight of 246 red fox ( Vulpes vulpes ) carcasses collected during hunts. A portion of these red foxes ( n = 153) was originally from habitats they shared with the golden jackal ( Canis aureus ), while the other portion ( n = 93) had almost no contact with this species. We analyzed the body weight of red foxes from both areas according to age (adult-cub) as well as gender. We have found that the younger animals that live sympatrically with the golden jackal weigh less than those from the golden jackal-free territory regardless of gender. In the case of adult red foxes, the habitat-related differences between body weight were found to be insignificant. These results suggest that the high level of nutritional niche overlap between sympatric red fox and golden jackal could affect the body weight of juvenile red foxes.