Abstract
Urbanization is currently one the most important causes of biodiversity loss. The Colombian Andes is a well-known hotspot for biodiversity, however, it also exhibit high levels of urbanization, making it a useful site to document how species assemblages respond to habitat transformation. To do this, we compared the structure and composition of bird assemblages between rural and urban habitats in Armenia, a medium sized city located in the Central Andes of Colombia. In addition, we examined the influence of urban characteristics on bird species diversity within the city of Armenia. From September 2016 to February 2017 we performed avian surveys in 76 cells (250 x 250 m each) embedded within Armenia city limits; and in 23 cells (250 x 250 m each) in rural areas around Armenia. We found that bird diversity was significantly lower in urban habitats than in rural habitats, and differed in species composition by 29%. In urban cells, with higher abiotic noise intensity and higher impervious surface area, we found lower bird diversity than that in urban cells with higher guadual (Guadua angustifolia patches), and forested surface areas. We did not find segregation of urban cells according to the species composition, although additional bird surveys inside urban forests remnant are needed to be more conclusive about this aspect. Altogether, our results highlight the importance of green areas embedded within cities to conserve bird diversity through reducing the ecological impact of urbanization on avian biodiversity.
Highlights
Urbanization is one of the most important causes of environmental transformation, reducing natural habitats and replacing them with impervious surfaces [1, 2]
When we compared the diversity of bird assemblages in the 76 urban cells with those obtained in the 23 rural cells, we found that species diversity was much higher in the rural habitat compared to the urban habitat (Fig 3)
According to our first objective and prediction, there was higher bird species diversity in the rural habitat than in the urban habitat; species composition differed between those habitats, yet species turnover between them was moderate
Summary
Urbanization is one of the most important causes of environmental transformation, reducing natural habitats and replacing them with impervious surfaces [1, 2]. The Colombian Andes is one of the most diverse regions in Latin America and on the planet, with many species exhibiting limited geographical ranges of distribution, and with evolutionary processes leading to speciation occurring at particular high rates [45, 46, 47] This region exhibits a high level of urbanization [48]. We studied the diversity of birds in and around a medium-size city located in the Central Andes of Colombia to answer questions about the effects of urbanization in the structure and composition of vertebrate communities in tropical regions of Latin America. We tested the relationship between urban and rural habitat characteristics (e.g. anthropogenic noise intensity, amount of impervious surface) and the structure of bird assemblages; we predicted that sites with high levels of urbanization would exhibit low species diversity. This is the first study in Colombia (but see [49]), and one of the few in the Neotropics, which quantifies the relationship between spatial variation in bird diversity and urban habitat characteristics
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