Urban landscape characteristics correlated with the synurbization of wildlife

The composition and complexity of urban landscapes can vastly affect the population dynamics and behavior of urbanized wildlife. Investigations on urbanized taxa have often described similar behavioral (reduced wariness and increased intraspecific aggression) and population dynamics (increased population densities) adaptations. The objectives of this study were (1) determine the relationship of habitat and matrix characteristics to squirrel density; (2) determine the relationship of habitat and matrix characteristics to squirrel behavior; (3) develop a conceptual model for the synurbization of wildlife. In the summer and fall of 2003 and 2004, we sampled gray squirrels (Sciurus carolinensis) at six urban parks for density, wariness, and intraspecific aggression. Structural characteristics of each park (size, canopy cover, tree basal area, and number of trees) and the adjacent matrix (tree cover, number of trees, building cover, and number of buildings) were used to develop models predicting gray squirrel density, wariness, and intraspecific aggression. Akaike Information Criterion (AIC) was used to evaluate and rank candidate models. Density and canopy cover were the most efficient predictors for wariness (AICs = 48.42, Wi = 0.500); density, park tree basal area, and matrix tree cover for aggression (AICs = 39.54, Wi = 0.567); park size, canopy cover, and number of matrix trees for density (AICs = 57.40, Wi = 0.237). The conceptual model presented in this paper expands on current understandings regarding the synurbization by introducing a minimum population density, a synurbization threshold, to be achieved before the population characteristics are in the range of synurbic populations.

► Habitat and matrix characteristics have an effect on the synurbization of wildlife.
► We introduce the terms synurbic shift and synurbization threshold.
► Conceptual model of the effects urban landscapes have on wildlife.
► Population density may be a driver for the synurbization of wildlife.