Comparative trophic ecology of two sympatric canids in the Brazilian Pampa

Abstract

Studies on resource utilization by carnivores are essential to assess the role of the species in the ecosystem. These studies help us to understand the mechanisms that influence vertebrate community structure and the relationships between predators and prey. The aims of this study were to compare and describe the food habits of the sympatric Pampas fox (Lycalopex gymnocercus) and crab‐eating fox (Cerdocyon thous) in the Brazilian Pampa, and to evaluate the food niche overlap between them, and infer aspects of habitat preferences on the basis of their prey. For the diet analyses, 25 stomach contents of Pampas foxes and 33 of crab‐eating foxes were collected. We identified 80 prey items (49 for the Pampas fox and 63 for the crab‐eating fox) and grouped them into eight main categories. Mammals and invertebrates were the most frequent items in the diets of both canids, followed by fruits. The trophic niche breadth of the Pampas fox (Bsta = 0.56) was larger than that of the crab‐eating fox (Bsta = 0.47). The diet overlap between them was Ojk = 0.58. However, a PERMANOVA test showed that diets did not differ between species or season. Our results showed that both L. gymnocercus and C. thous had generalist diets, with a great diversity of prey, but based on similar main food items. Items that contributed the most to the diet of the Pampas fox were insects (Gryllotalpidae and Scarabaeidae) and cavies (Cavia aperea) and those that contributed the most to the diet of the crab‐eating fox were fruits of Syagrus romanzoffiana, beetles (Scarabaeidae), amphibians (Leptodactylus spp.) and cavies. This is the first study to describe and compare the food habits of these two species, occurring in sympatry in the Brazilian Pampa.

Anatomical variations in cervical vertebrae in two species of neotropical canids: What is the meaning?

“…Thus, these canids can be considered phylogenetically similar species among other carnivores in the same area. Furthermore, these foxes are the most common canids in southern Brazil, have similar morphology and overlap their ecological niche in many aspects (Bossi et al., 2019; Kasper et al., 2016). Therefore, the occurrence of similar bone deformities in both species in the same area suggests they might be affected by a common environmental cause.…”

“…Thus, these canids can be considered phylogenetically similar species among other carnivores in the same area. Furthermore, these foxes are the most common canids in southern Brazil, have similar morphology and overlap their ecological niche in many aspects (Bossi et al, 2019;Kasper et al, 2016).…”

“…Cerdocyon thous is the wild canid with the widest distribution in the South American continent, while Lycalopex gymnocercus is a canid more restricted to the southern cone of the continent. Both occur in sympatry in the Pampa biome with a generalist and highly diversified diet, including invertebrates, small rodents, fruits and amphibians (Bossi, Migliorini, Santos, & Kasper, 2019).…”

Co-occurrence, habitat use and activity pattern of carnivore species in a coastal area of Argentina

“…Both the RAI values and the naïve occupancy (i.e., the proportion of sampling site where a species is recorded) showed that the Pampas fox is the most common carnivore species in the coastal area of the southern part of Buenos Aires province, followed by the Geoffroy's cat. The numeric dominance of Pampas fox is not surprising, because this canid is a very adaptable carnivores, capable of opportunistically feed on a variety of prey (e.g., Bossi, Migliorini, Santos, & Kasper, 2019;Castillo, Birochio, Lucherini, & Casanave, 2011;Farias & Kittlein, 2008) and still relatively common in the agroecosystems of the Pampas. Conversely, the relatively high frequency of records and occupancy of the Geoffroy's cat in our study area, especially when compared to those of C. chinga and G. cuja, was unexpected, based on the available information on the present-day Pampas landscapes.…”

“…Because Pampas foxes readily eats carrion and have been reported to prey on several animals associated to saline water, such as crabs, crustaceans, and even fish (García and Kittlein, 2005;Lucherini and Luengos Vidal, 2008;Bossi et al, 2019), these canids could be expected to use the areas close to the shoreline more intensively than other carnivores. We found little support for this hypothesis.…”