Replacement of native by non-native animal communities assisted by human introduction and management on Isla Victoria, Nahuel Huapi National Park

MARTIN ALBARRACIN, VALERIA LETICIA; NUÑEZ, MARTIN ANDRÉS; AMICO, GUILLERMO

PeerJ

PeerJ, Inc

Año: 2015 vol. 3

2167-8359

One of the possible consequences of biological invasions is the decrease of native species abundances or their replacement by non-native species. In Andean Patagonia, southern Argentina and Chile, many non-native animals have been introduced and are currently spreading. On Isla Victoria, Nahuel Huapi National Park, many non-native vertebrates were introduced ca. 1937. Records indicate that several native vertebrates were present before these species were introduced. We hypothesize that seven decades after the introduction of non-native species and without appropriate management to maintain native diversity, non-native vertebrates have displaced native species -given the known invasiveness and impacts of some of the introduced species-. We conducted direct censuses in linear transects 500m long (n=10) in parallel with camera-trapping (1253 camera-days) surveys in two regions of the island with different levels of disturbance: high (n=4) and low (n= 6) to study the community of terrestrial mammals and birds and the relative abundances of native and non-native species. Results show that currently non-native species are dominant across all environments; 60.4% of census records and 99.7% of camera trapping records are of non-native animals. We detected no native large mammals; the assemblage of large vertebrates consisted of five non-native mammals and one non-native bird. Native species detected were one small mammal and one small bird. Species with a highest trapping rate were red and fallow deer, wild boar, silver pheasant (the four species non-native) and chucao (a native bird). These results suggest that native species are being displaced by non-natives and are currently in very low numbers.