¿Predicen los rasgos biológicos de las aves su ocupación del gradiente de urbanización en el Área Metropolitana de Mendoza?

Abstract

We studied the spatial and temporal dynamics of bird assemblages in parks located within an urban gradient of the Mendoza Metropolitan Area (AMM), Argentina. Under the assumption that urbanization filters the species from the regional pool according to their biological traits, we defined tolerant and urban avoider species as those having at least four up to six traits of every category, and predicted that urban tolerant species reach maximum densities in urban or urban-suburban matrixes, whereas avoiders species are more abundant in peri-urban or peri-urban-suburban matrixes. In breeding and non-breeding seasons of 2017 and 2018, we recorded birds on strip transects on the three matrixes. Our results supported the idea and allowed the identification of two environmental filters: one located between the AMM and its surroundings, which admits urban-tolerant common species, and other in downtown Mendoza, which prevents the access of infrequent urban avoiders and maintains several urban tolerant species. Under the hypothesis that urban centers support few very abundant species and that more intermediate habitats host the greatest species richness, we estimated total abundance and richness in the same matrixes, but we find neither greater abundance in the urban matrix nor greater richness in the suburban matrix. These results could be related to the fact that the suburban matrix offers a very restricted ecotone within the AMM. The plausible higher stability of climate and resource supply in downtown Mendoza was not associated with more temporal stability of bird assemblages. Biological traits allow to identify significant environmental filters while predicting and explaining the spatial occurrence of numerous bird species. Some of our results highlight the greater importance of urban parks with respect to urban streets as habitats that mitigate the effect of urbanization on birds, a valuable information for sustainable-urban development plans.