Ecologia alimentar de três espécies de canídeos do Cerrado: variações intra e interespecíficas

Abstract

Considering that feeding ecology is closely related to the ecological functions of animal populations in their respective ecosystems, this study aimed to analyze the intraspecific (sex and age) and interespecific (resource partitioning) variations in the diet of three canid species co-occurring in the Cerrado biome (crab-eating fox, maned wolf and hoary fox). The specific objectives were: to verify if the three species consume different food categories and/or proportions and to identify the main items for each species (chapter 1); to verify if there are feeding differences between sexes for the crab-eating fox and the hoary fox species, to describe the diet of hoary fox cubs up to four months of age and to compare it to that of the adults of their same species (chapter 2). We used 155 scat samples from adults, 60 of these from crabeating foxes, 30 from maned wolves and 65 from hoary foxes (chapter 1); and 125 scat samples, being 29 from female and 31 from male crab-eating fox individuals, 34 from female and 31 from male hoary fox individuals, and 230 scat samples from hoary fox cubs up to four months of age (chapter 2). We identified and separated the food items into six food categories (Vegetables, Insects, Anurans, Squamatans, Birds, and Mammals) and then we performed the following calculations: absolute frequency, occurrence frequency, relative frequency, G test, and trophic niche breadth and overlap. Crab-eating foxes and hoary foxes had higher frequencies in the Insects category, with the former having a higher consumption of coleoptera and orthoptera, and the other consuming coleoptera, orthoptera and isoptera in about the same proportion. Maned wolves, however, had a higher frequency in the Vegetables category, with the maned-wolf fruit being the main consumed item. Crab-eating foxes and hoary foxes showed low niche breadth and high niche overlap between each other, while maned wolves presented a greater niche breadth and less niche overlap with those (chapter 1). Males and females of crab-eating foxes and hoary foxes consumed mostly insects, followed by plants and mammals, had low uniformity in the resource utilization and a high niche overlap between sexes. In crab-eating foxes’ diet, males had higher consumption of insects and anurans, while females consumed vegetables and mammals in greater proportion. These differences, however, were not significant. For hoary foxes, males consumed only a greater proportion of plants compared to females. Hoary fox cubs presented an omnivorous diet, mainly consuming insects, vegetables and small mammals. The niche breadth was low and when comparing their diet to that of the adults, it is noticed that the latter only consume more insects than the cubs (chapter 2). Our results can contribute to increase the knowledge of the basic aspects of the biology and the ecological function of the canids in the Cerrado over time and are useful for comparison to future studies.