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Martin-Albarracin VL, Nuñez MA, Amico GC.2015. Replacement of native by non-native animal communities assisted by human introduction and management on Isla Victoria, Nahuel Huapi National Park. PeerJ PrePrints3:e1415v1https://doi.org/10.7287/peerj.preprints.1415v1
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.
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Models fitted for Pheasant, Chucao, Deer and Boar and their corresponding AIC values. Functions: half-normal (hn), hazard-rate (haz), exponential (exp); detection covariates: type of environment (Env); density covariates: level of disturbance (Dis).
Raw Data on camera trapping captures for terrestrial species
Dataset showing data on camera trapping captures for terrestrial species on Isla Victoria. Each row is an independent capture of an animal. Columns describe the species detected, the transect sampled, the disturbance level, the number of individuals (group size) and the type of environment.
Raw Data on distance sampling for vertebrate species
Dataset showing data on distance sampling for vertebrate species on Isla Victoria. Each row is an animal detection. Columns describe the transect sampled, the species detected, the type of environment, the transect length, the number of individuals (group size) and the perpendicular distance of the animal to the linear transect.