Tolerance to noise in 91 bird species from 27 urban gardens of Iberian Peninsula

Urban noise is one of the most important factors explaining the abundance of birds in urban areas. If urban planners have information on the effects of noise on diverse avian species, they can design better gardens that can be useful for the conservation of endangered species. In this sense, many studies have been realized in diverse urban areas across the world. However, information on the exact effects of noise on urban birds in SW Iberian Peninsula does not exist. In this paper, we show the first study on the effects of urban noise on 91 bird species in 27 parks in diverse cities and villages of Spain and Portugal. Our study includes from rural areas with noise levels below 40 dB, to parks inside big cities such as Madrid and Sevilla that surpass 70 dB. The range of noise conditions, studied parks and the seasonal and annual replication of this study permits extraction clears conclusions. In this sense, the ten species most affected by noise, in terms of percentage of explained variance, are: Regulus regulus with 34.62% variability associated with noise, Streptopelia turtur (24.24%), Dendrocopos minor (20.39%), Buteo buteo (15.15%), Hirundo daurica (13.15), Corvus corax (11.09%), Oriolus oriolus (10.23%), Cettia cetti (6.47%), Passer hispanoliensis (6.33%) and Sylvia melanocephala (5.82%). Our data demonstrates that many of these protected species could be attract to urban gardens if noise levels were reduced below 50 dB by using, for example, acoustic barriers.

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► We determine the effect of urban noise on 91 bird species in 27 sampling areas.
► The more sensible species to noise are rare in parks and present any status of protection.
► The threshold that separate areas with rare and common species is 50 dB.
► We recommend the use of acoustic barriers to increase the endangered species.