How to build a biodiverse city: environmental determinants of bird diversity within and among 1581 cities

Abstract

Cities are novel environments compared with the evolutionary history of the species that reside within them. Collectively, cities and their fauna can be thought of as ecosystems, recognized as playing a critical role in supporting global biodiversity, but they are fundamentally a combination of old species surviving or thriving in a new environment, and the mechanisms and underlying processes which support biodiversity within cities have not been investigated at broad macroecological scales. We aimed to understand-at a broad macroecological scale-how biodiversity responds both among and within cities. We integrated > 5 million eBird citizen science observations with remotely sensed landcover products throughout 1,581 cities within the continental United States. We first investigated the species-area relationship as it pertains to cities and compared the slope of this relationship to randomly sampled polygons. Second, we investigated how biodiversity responds to an urbanization gradient at the level of localized bird observations. We found strong support for the longstanding species-area relationship theory: geographically larger cities had greater species richness. Surprisingly, the species-area relationship was greater in cities when compared to the overall relationship for randomly sampled polygons in the study region (continental United States), which included many different land use and land cover types. Our finding suggests that diverse and heterogeneous cities play a significant role in supporting biodiversity. We also found that there is a consistent threshold where the level of urbanization begins to profoundly and negatively affect biodiversity. Critically, urban planning at the city-scale and at a local-scale (e.g., neighborhood) should focus on preserving attributes of water and tree-cover for increased biodiversity to keep as much of the city as possible above this threshold value.

Housing or habitat: what drives patterns of avian species richness in urbanized landscapes?

“…Relative to housing cover, landscape-scale canopy tree cover did not have a strong influence on the richness of native, terrestrial or forest birds across the urbanization gradient sampled. This contrasts with other studies in urban environments which have reported a positive relationship between avian species richness and canopy tree cover, either for landscape units (Chamberlain et al 2019;Callaghan et al 2020) or sites with surrounding tree cover (Callaghan et al 2018;Lerman et al 2021). The lack of a relationship between landscape-scale tree cover and bird richness here may be due to several factors.…”

Acoustic communities in an environmental gradient from native to urban areas in Central Brazil

“…This last index is negatively related to the distance from the cerrado and positively related to the diversity of environments and the number of patches present in the landscape, suggesting an increasing diversity of species. This situation is already observed in other regions (Callaghan et al, 2021;de Groot et al, 2021;Garizábal-Carmona & Mancera-Rodríguez, 2021). Consequently, these results suggest that areas composed of native vegetation, or areas that present the mosaic mentioned above, could have higher species richness than the intensely urbanized areas as shown by Machado et al (2017).…”

Effectiveness of using nest boxes as a form of bird protection after building modernization

“…Tomasevic and Marzluff (2017) showed that in the most heavily urbanized areas, classed as those with below 12% forest cover on a 1 km 2 scale, secondary hole-nesters nested primarily in places of anthropogenic origin, using nest boxes or platforms (59% of broods). Thus, when designing buildings, modern architects should account for the habitat needs of hole-nesting species, and urban planners should preserve old trees with holes or, alternatively, introduce nest boxes to the environment to support the occurrence of endangered hole nesting birds (Jokimäki et al 2018;Callaghan et al 2021). Rosin et al (2020) suggested that urban designers and architects should draw inspiration from traditional architecture and include different types of nest boxes in their plans.…”