Environmental variability as a predictor of behavioral flexibility in urban environments

Despite numerous studies comparing behavioral flexibility between populations from rural and urban habitats, we still don't understand the relationship between level of urbanization and flexibility. We suggest that the problem stems from ignoring the heterogeneity within urban habitats. In this empirical study we show that urban change (i.e., the change in urbanization level over time) better explains behavioral flexibility and other related behaviors in house sparrows than the level of urbanization. Global urbanization processes have highlighted the importance of understanding the effects of urban habitats on animal behavior. Behavioral changes are usually evaluated along an urbanization gradient, comparing urban and rural populations. However, this metric fails to consider heterogeneity between urban habitats that can differ significantly in their characteristics, such as their level of environmental variability. We suggest incorporating dimensions of environmental variability into the urbanization metric when evaluating behavioral changes. We tested the importance of both level of urbanization and level of urban change (i.e., the rate of anthropogenic changes measured as the change in the level of urbanization over time) on animals' behavioral flexibility by comparing reversal learning abilities in house sparrows from sites differing in the rate of urbanization and urban change levels. We show that at least for males, urban change better explains levels of behavioral flexibility than urbanization level. We further show that urban change corresponds to other behavioral traits such as scrounging behavior and foraging activity. Thus, considering environmental stability and predictability in the form of urban changes can help better understand the mechanisms allowing behavioral changes and adaptations to urban environments. Evaluating the dynamics of the urban built environment could provide a better metric with which to understand urbanization effects on wildlife behavior and an important next step in urban ecology.