A continental measure of urbanness predicts avian response to local urbanization

Abstract

Understanding species‐specific relationships with their environment is essential for ecology, biogeography and conservation biology. Moreover, understanding how these relationships change with spatial scale is critical to mitigating potential threats to biodiversity. But methods which measure inter‐specific variation in response to environmental parameters that are also generalizable across multiple spatial scales are scarce. We used broad‐scale avian citizen science data, over continental Australia, integrated with remotely‐sensed products, to produce a measure of urban‐tolerance for a given species at a continental‐scale. We then compared these urban‐tolerances to modelled responses to urbanization at a local‐scale, based on systematic sampling within four small cities. For 49 species which had sufficient data for modelling, we found a significant relationship (R2 = 0.51) between continental‐scale urbanness and local‐scale urbanness. We also found that relatively few citizen science observations (~250) are necessary for reliable estimates of continental‐scale species‐specific urban scores to predict local‐scale response to urbanization. Our approach demonstrates the applicability of broad‐scale citizen science data, contrasting both the spatial grain and extent of standard point‐count surveys generally only conducted at small spatial scales. Continental‐scale responses in Australia are representative of small‐scale responses to urbanization among four small cities in Australia, suggesting that our method of producing species‐specific urban scores is robust and may be generalized to other locations lacking appropriate data.

Urban affinity and its associated traits: A global analysis of bats

“…Recently, an adjustment of urban affinity indices that aims to account for the potential effects of range size, sampling biases and interspecific competition has been published and provides a potential solution for biased data (Callaghan, Cornwell, et al, 2021;Callaghan, Major, et al, 2020). In any case, the scores of the indices we present should not be interpreted as absolute but as relative values of urban affinity that allow comparing different indices and species with each other but do not necessarily reflect the actual urban affinity.…”

Thermal flexibility and a generalist life history promote urban affinity in butterflies

“…These traits may be important for predicting space use within urban areas, but not urban affinity as measured in our current analysis. Future work should formally test how species-specific responses to urbanization varies among spatial scales in butterflies (e.g., Callaghan, Benedetti, et al, 2020;Callaghan, Major, et al, 2020;Callaghan, Ozeroff, et al, 2020;Moll et al, 2020). In addition to our limitations in the spatial resolution, we highlight that we only looked at urban preferences in butterflies averaged across the full annual cycle, but some species may increase their use of urban areas during certain times of the year.…”

“…After each observation was assigned a measure of VIIRS nighttime lights at a continuous scale, each species had a distribution of their frequency of observations along an urbanization gradient (e.g., Figure S3). Only species with a minimum of 250 observations were considered for analyses as this has been shown previously to minimize the variance in response to urbanization among species and be applicable at localized spatial scales (Callaghan, Benedetti, et al, 2020;Callaghan, Major, et al, 2020). Because each species differs in their geographic extent across Europe (Schweiger et al, 2014) we adjusted the distribution of VIIRS night-time light levels for each species by standardizing for (1) the available urban habitat in a species' range and (2) the bias in sampling observations in a species' range relative to urban habitat Liu et al, 2021).…”

“…However, this approach assumes that because urban cover changes relatively slowly, the relative patterns from 2014 onwards represents the relative difference between high and low urban cover, and additionally we note that the majority of our GBIF occurrence records are derived from post 2014. See Callaghan, Benedetti, et al (2020), Callaghan, Major, et al (2020), Callaghan, Ozeroff, et al (2020) for more details about this process. Spatial analyses were performed in Google Earth Engine (Gorelick et al, 2017).…”

Influence of habitat type and distance from source area on bird taxonomic and functional diversity in a Neotropical megacity

“…In this sense, habitats near the urban fringe may play a major role in bird conservation in relation to those further away in Neotropical megacities (Puga-Caballero et al 2014). Thus, distance from forest, vegetation and urban characteristics may influence the resilience of forest and non-forest birds, being crucial for the maintenance of rich bird assemblages and functional diversity within the cities (Croci et al 2008;Pauw and Louw 2012;Oliveira Hagen et al 2017;Callaghan et al 2020), as well as for the provision of ecosystem services (Carbó-Ramírez and Zuria 2011; Morrison and Lindell 2012;Sekercioglu 2012;de Coster et al 2015). In relation to larger native forests (source), we evaluate herein whether bird species richness and functional diversity (represented by diet, bill length, biomass, foraging and nesting strata, wing length, migratory behavior, and habitat preference), including taxonomic and functional compositions, are affected by (1) increased distance from native forest source, and (2) vegetation (green) and (3) urban infrastructure (gray) characteristics along the forest-urban gradient.…”