At what spatial scale(s) do mammals respond to urbanization?

Abstract

Spatial scale is fundamental in understanding species-landscape relationships because species' responses to landscape characteristics typically vary across scales. Nonetheless, such scales are often unidentified or unreliably predicted by theory. Many landscapes worldwide are urbanizing, yet the spatial scaling of species' responses to urbanization is poorly understood. We investigated the spatial scaling of urbanization effects on a community of 15 mammal species using ~60 000 wildlife detections collected from a constellation of 207 camera traps across an extensive urban park system. We embedded a bivariate Gaussian kernel in hierarchical multi-species models to determine two scales of effect (a scale of maximal effect and a broader scale of cumulative landscape effect) for two biological responses (occupancy and site visit frequency) across two seasons (winter and summer) for each species. We then assessed whether scales of effect varied according to theoretical predictions associated with biological responses and species traits (body size and mobility). Scales of effect ranged from < 50 m to > 9000 m and varied among species, but not as predicted by theory. Species' occupancy generally showed a weak response to urbanization and the scale of this effect was both highly uncertain and consistent across species. We did not detect any relationship between scales of effect and species' body size or mobility, nor was there any evident pattern of scaling across biological response or seasons. These results imply that 1) urbanization effects on mammals manifest across a very broad spectrum of spatial scales, and 2) current theories that a priori predict the scale at which urbanization affects mammals may be of limited use within a given system. Overall, this study suggests that developing general theory regarding the scaling of species-landscape relationships requires additional empirical work conducted across multiple species, systems and timescales.

Scales of Effect for Urban Mammals Vary Among Species and Environmental Attributes

“…No two land-cover covariates included in our top models for individual species exhibited the same scale of effect. Although past studies have identi ed many urban taxa, such as birds (Hostetler and Holling 2000, Pennington and Blair 2011, Hallman and Robinson 2020) and arthropods (Bennett and Gratton 2012) as responding to the environment at multiple spatial scales, our results support recently described evidence for similar multi-scale relationships between mammal species and urban environments (Moll et al 2020). Additionally, and in line with our expectations, of the nine scales of effect examined across these three species, we found only one shared scale of effect across species (fox squirrel and opossum), for impervious surface coverage at 100 meters.…”

“…Models that fail to account for scale of effect and rely on a single spatial scale selected a priori can mischaracterize the strength and direction of relationships (Miguet et al 2016, Moll et al 2020, or nd no relationship where one may truly exist over a smaller or bigger spatial extent than used in modeling (Holland and Yang 2016). For example, multiple studies have reported a negative relationship between coyote (Canis latrans) occupancy and urban intensity as measured by housing density (Fidino et al 2020) or proportional impervious cover (Wait et al 2018) within 1 km buffers, yet a study that measured urban intensity over a larger extent (3 km) identi ed a positive relationship (3 km, Ordeñana et al 2010).…”

“…While a growing number of studies, among them analyses of urban mammals (Moll et al 2020), use multiple spatial extents selected in a biologically-informed manner to more accurately pinpoint scales of effect in species-habitat investigations (e.g., Chandler and Hepinstall-Cymerman 2016, Galán-Acedo et al 2018, Stevens and Conway 2020), they do not yet indicate clear patterns regarding the appropriate scale or scales of effect for urban mammals. We sought to build understanding of these scales of effect by identifying whether single or multiple scales of effect best characterize habitat relationships of urban mammals, and whether and how scales of effect vary among urban mammals and environmental attributes.…”

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

“…These traits may be important for predicting space use within urban areas, but not urban tolerance 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., Moll et al 2020;Callaghan 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.…”

Animal Behavioral Responses to the COVID-19 Quietus

“…It is also important to note that via the presentation of this typological framework ( Figure 1 ), we are not presuming directionality of animal responses. While many animal species are negatively affected by human activity, others experience positive feedbacks [ 7 ]. Additionally, the COVID-19 pandemic triggered a series of complex direct and indirect effects on animal populations and the environment [ 8 ].…”