Avian assemblages in native and exotic forests in the reproductive season in a protected area of El Espinal de Entre Rios, Argentina.

Avian assemblages in native and exotic forests in the reproductive season in a protected area of El Espinal de Entre Rios, Argentina. The multiple use reserve "Parque Escolar Rural Enrique Berduc" represents a remainig of the Espinal forest from the province of Entre Rios, Argentina, and presents a serious increasing of exotic species of trees. We studied bird assemblages comparing native (BN) and exotic forests (BE) between October 2003 and March 2004. We sampled monthly eight stations of counting points both in BN and BE. Using a repeated means variance analysis, we evaluated differences in specific richness, abundance, diversity, evenness and abundance of trophic guilds (frugivore-insectivore - Fl, granivore - G, insectivore - I, and omnivore - O) between types of forests. Although, we used abundance range curves to compare the assemblages, as well as the total richness with the estimators Chao1 and Chao2, rarefaction curves. Richness, abundance, and diversity changed significantly between forests types (F = 29.02, P < 0.0001; F = 26,55, P = 0,0001; F = 17.26, P = 0.001, respectively), while evenness did not show differences. The estimators Chao1 and Chao2 suggest that new species should be detected in the NF. I and O trophic guilds showed statistically significant differences towards NF (F = 32.85, P < 0.0001; F = 7.59, P = 0.015; respectively), while G end Fl did not show significant differences between forests. Our results suggest that the replacement of a BN to a BE should be carrying to a richness lost of bird species and individual abundances. Added to, the multiple threaten factors that affects the Espinal's biodiversity (e.g., urban and agricultural frontiers expansion, scarcity of conservation areas, hunting, etc), wide zones are being invaded by exotic plants, standing out a critical situation that requires more researchs and urgent conservation actions.