Use of habitat, size of prey, and food-niche relationships of two sympatric otters in southernmost Chile

Abstract

In Magallanes (southernmost Chile), the marine otter Lutra felina tends to use more open and wave-exposed coastal areas, whereas L. provocax is found in more protected habitats. To investigate the hypothesis that the two species segregate habitats to avoid competition for food, we surveyed the available literature on food habits and analyzed food-niche relationships of both species of otters in Magallanes. Overlap of diet between species of otters was relatively high, and L. provocax tended to have a narrower diet than L. felina. Both species consumed prey of similar size. These findings are consistent with the use of different habitats to avoid competition for food resources. However, alternate models, including habitat segregation resulting from differential abilities of the two species at catching prey in more wave-exposed habitats, deserve some attention. Our analysis also revealed that niche breadth and size of prey taken by L. felina at three sites along the Chilean coast were relatively similan. At Chiloe, however, L. felina exhibited the narrowest diet and consumed the largest prey. Although such a difference might be related to variation in abundance of prey among localities, it may also have resulted from the relatively small sample available for Chiloe.