Composition, structure and seasonal variation of the bird community in the Botanical Garden of Fundación Miguel Lillo, Tucumán, Argentina

Abstract

Environmental disturbances caused by human activities have a negative impact on biodiversity. Among these, it is expected that changes from natural to urban environments will increase during this century due the high rate of human population growth. This prediction has generated an interest in determining the role that urban green spaces play in preser ving biodiversity. Most of the original Premontane Subtropical Forest (Yungas) of the Tucumán Province, Argentina, has been replaced by urbanization and agriculture. However, cities in this province present a series of green spaces that differ from one another in the structure of its vegetation. The Botanical Garden of the Fundación Miguel Lillo, in San Miguel de Tucumán, was created approximately 60 years ago and is now surrounded by an urban matrix with scarce vegetation. This garden which covers 0,7 hectares, presents all the typical vegetation strata of the original forest. We sampled the bird community within this botanical garden for two years, using the fixed-radius point counts. We recorded 85 bird species: two exotic species, 14 species from the original Yungas forest, and the rest native species of ample distribution or species from the Chaco-Pampeana region. The community was divided into four assemblages based on trophic strategies. The assemblage with the highest diversity and the most species is that of birds that search for food in the vegetation. These results, combined with other studies done in the same city, suggest that the structure of the vegetation plays a major role in preserving native bird species within cities.