How human constructions influence the spatial distribution of birds of prey in Northwest Patagonia.

BARBAR, FACUNDO; VICTORIA WERENKRAUT; JUAN MANUEL MORALES; LAMBERTUCCI, SERGIO AGUSTÍN

San Carlos de Bariloche

Congreso; I Worldwide Raptor Conference.; 2013

UNComa, Raptor Research Foundation, Neotropical Raptor Network, World Working Group on Birds Of Prey and Owls

Human activities affect biological diversity and species distribution patterns in numerous ways. For instance, cities produce physical changes which generate landscape homogenization. Moreover, roads are known to generate habitat fragmentation. Both sources of human disturbance modify the availability of resources and generate novel environments where generalist species are often abundant (considered ?winners?), and more specialist species tend to be absent (?losers?). We studied the abundance, richness and composition of raptor species, including carrion eaters, generalist hunters and facultative species (families Cathartidae, Accipitridae and Falconidae) in relation to the distance to roads and cities. We worked in Northwestern of Patagonia, a region with the highest population growth rate of Argentina, but still having large unpopulated areas. We conducted stationary point counts with a fixed observation radius and time, recording every raptor inside a grid of 22 km by 8 km (77 point counts). We then related the presence of raptors with different distances to sources of human disturbances as cities, farms, roads, fences and power lines using zero-inflated Poisson regressions. We found that raptor richness and abundance were positively associated with human environments. These results are driven mostly by a strong association of the medium-size generalist species to human environments which is consistent with the ?winner/loser species? hypothesis. However, we did not find enough evidence to suggest negative effects on those species presumably called ?losers?. A possible explanation for this may relay in the fact that large species (i.e. Andean Condor) need large home-ranges and they could be flying above suboptimal environments to reach those areas where human pressure is less strong. Considering the current scenario of roads and cities increase in Argentina, our results suggest that the structure of raptor communities will change in the short future, by the increase of the species which take advantage of those novel environments.