Spatial and food niche use of two sympatric native and nonnative herbivores in arid Argentina

BOBADILLA S. YASMIN; OJEDA RICARDO A.; DACAR MARIANA A.; CUEVAS M. FERNANDA; JAKSIC M. FABIÁN

Conferencia; 100TH ANNUAL MEETING OF THE AMERICAN SOCIETY OF MAMMALOGISTS; 2021

The coexistence of ecologically similar species is facilitated by differential use of niche axes (i.e. habitat, diet, and time). We compare the use of spatial and food resources of one native (plains viscacha, Lagostomus maximus) and one nonnative herbivore (European rabbit, Oryctolagus cuniculus) in a protected area of the Monte ? Patagonia arid land of central western Argentina. We expected herbivores to show different responses in the use of the two niche axes, in association 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 food niches, and dietary overlaps. Our findings show that resources were not markedly segregated at the habitat level, but segregate to some degree in the use of space at the microhabitat-level. Native and nonnative herbivores largely overlapped in the food niche dimension. Diet composition was dominated by grasses during the wet season, but under conditions of resource limitation (dry season), the native herbivore differed in feeding strategy from the nonnative herbivore. The native plains viscacha broadened its trophic niche (high diet richness) when items were less abundant. These results deepen our understanding of likely underlying mechanisms that allow coexistence of native-nonnative herbivores in arid ecosystems.