Urban noise and surrounding city morphology influence green space occupancy by native birds in a Mediterranean-type South American metropolis

Abstract

Urban green spaces provide natural habitat for birds in urban landscapes, yet the effects of noise and surrounding urban morphology on bird community structure and distribution are not well understood in Latin America, the second most urbanized region in the world. Santiago of Chile is the single city belonging to the Mediterranean ecosystem in South America and is subject to extensive urbanization as seen throughout Latin America. We examined the role of 65 urban green spaces—6 large urban parks (PAR) and 59 small green spaces (SGS)—in harboring native birds during winter 2019, analyzing the quality of green areas in terms of vegetation (i.e. NDVI, native vegetation, and tree cover), exotic bird species, noise levels, and surrounding urban morphology (i.e. building height and cover). Significantly higher noise levels were detected in SGS, along with significantly greater exotic bird (n = 4) richness and abundance than PAR, which possessed significantly greater native bird (n = 25) richness and abundance. Native birds were more abundant than exotic birds in green spaces with average noise levels < 52 dB and average NDVI > 0.5. Occupancy models indicate that green space occupancy by 50% of modeled native bird species was influenced by maximum noise levels, playing a larger role than vegetation (30%) and urban morphology (0%). We stress the importance of developing networks of large green spaces in rapidly urbanizing regions, with abundant tree cover, surrounded by smaller urban morphology, and regulating noise levels to ensure the conservation of native bird communities in cities, particularly those that are threatened.

Urban Low-Rise Residential Areas Provide Preferred Song Post Sites for a Resident Songbird

“…However, most previous studies have focused on the comparison between urban and rural areas in terms of birdsong. Environmental differences within cities also affect birds’ community structure and distribution, e.g., the differences in the urban morphology (i.e., building height and density) in parks or residential areas [ 15 ]. With the development of urbanization in China, more and more high-rise residential buildings (at least 10–15 stories, with many even over 30 stories) have been constructed in recent years [ 16 ].…”

Long-term Christmas Bird Counts describe Neotropical urban bird diversity

“…However, differences within each city might also be related to factors that were not analyzed in this study, including the spatial configuration of the green areas found in these sample sites, such as their size, shape, or their connectivity, or aspects related to the quantity and quality of the habitat they offer [62]. Likewise, factors that characterize the urban matrix in which bird count sites are immersed (e.g., building density or urban noise) could influence limitations in their ability to retain some species [63]. Some research has shown that larger cities with a higher degree of urbanization lose highly specialized groups and maintain species that are ecologically similar to each other, a process known as biotic homogenization [64,65] that would not be supported in Bogotá and Medellín, accompanied by the high levels of complementarity between the sites in each city.…”

“…However, differences within each city might also be related to factors that were not analyzed in this study, including the spatial configuration of the green areas found in these sample sites, such as their size, shape, or their connectivity, or aspects related to the quantity and quality of the habitat they offer [62]. Likewise, factors that characterize the urban matrix in which bird count sites are immersed (e.g., building density or urban noise) could influence limitations in their ability to retain some species [63].…”

Long-term Christmas Bird Counts describe neotropical urban bird diversity

“…However, differences within each city might also be related to factors that were not analyzed in this study, including the spatial configuration of the green areas found in these sample sites, such as their size, shape, or their connectivity, or aspects related to the quantity and quality of the habitat they offer [ 62 ]. Likewise, factors that characterize the urban matrix in which bird count sites are immersed (e.g., building density or urban noise) could influence limitations in their ability to retain some species [ 63 ]. In future studies, such spatial or temporal information should be included as urban covariates to enhance analysis capabilities (i.e., GLMs, GLMMs, or hierarchical models) that allow the identification of the size of this covariates effect and its contribution to explaining some of the bird community patterns found, as already described in other short-term studies in neotropical cities [ 64 – 66 ].…”