Spatial and trophic niche utilization of two sympatric native and nonnative herbivores in arid Argentina

BOBADILLA, SABRINA YASMIN; DACAR, MARIA ANA; JAKSIC, FABIAN; OJEDA, RICARDO; CUEVAS, MARÍA FERNANDA

Congreso; 100th Annual Meeting of the American Society of Mammalogists; 2021

American Society of Mammlogists

The coexistence of ecologically similar species is facilitated by differential use of niche axes (i.e. habitat, diet, and temporal gradients). We compare the utilization of spatial and trophic resources of native (plains viscacha, Lagostomus maximus) and nonnative herbivores (European rabbit, Oryctolagus cuniculus) in a protected area the Monte ? Patagonia arid land of central western Argentina. We expected herbivores to show different responses in the use of the niche axes associated with seasonal changes in resource availability. We evaluated habitat use at the habitat-type level through Chi-squared goodness of fit tests and Bonferroni confidence intervals and microhabitat-level using generalized linear mixed-effects models. We analyzed seasonal compositions of the diets, breadth of the trophic niches, and dietary overlaps. Our findings show that resources were not markedly segregated at habitat. The European rabbit have a greater degree of selectivity than plains viscacha in the utilization of habitats-types. Native and nonnative herbivores overlapped in the trophic niche dimension but segregated to some degree in the use of space at microhabitat level. Diet composition was dominated by grasses during wet season. Under conditions of resource limitation (dry season), native herbivore differed in feeding strategy from the nonnative herbivore. These results deepen our understanding of possible underlying mechanisms that allow coexistence of wild native-nonnative herbivores in arid ecosystems.