Do exotic invasive mammals disturb the native fauna? Spatiotemporal distribution and overlap between species in a national park of Argentina.

Abstract

Monitoring the invasive exotic species and their effect on native fauna is fundamental for their effective control. The objective of this research is to evaluate the spatiotemporal distribution and overlap of medium-large-sized fauna in El Palmar National Park, Argentina, to consider potential negative interactions between native and exotic species. Camera traps were distributed in 27 sites between 2017 and 2019. Spatial and temporal overlap was estimated for every pair of exotic-native taxa. With 2673 camera days, two exotic and seven native taxa were recorded. All species were distributed along the extension of the National Park but in different numbers of sites. Exotic axis deer (Axis axis) was recorded in all sites but one, and exotic wild boar (Sus scrofa) occurred at only one-third of the sites surveyed. The occurrence of native mammals ranged between 26% (Geoffroy's cat, Leopardus geoffroyi) and 67% (capybara, Hydrochoerus hydrochaeris). Spatial overlap between native and exotic species was high overall and was higher in winter when species moved over larger areas to look for limited resources. Except for greater rhea (Rhea americana), which was diurnal, all species had crepuscular or nocturnal patterns. Both exotic species had an intermediate/high overlap in their activity pattern with almost all native species, including some species with similar diets, but the hours of their maximum activities did not strictly coincide. However, the existence of differences in the exotic species' activity patterns compared to their patterns in other areas where they inhabit could indicate segregation in daily activity to relax competition.