Urban areas allow lizards to exploit perch preferences not available in natural habitats

Background/Question/Methods

Urbanization typically destroys native ecosystems, but it may also create opportunities for some species to exploit preferences they may not otherwise express in natural habitats. Urban development often removes natural forest, replacing it with artificial structures (i.e. walls, pavement, and lamp posts) and managed, mostly non-native, vegetation assemblages. The structural microhabitat is an important dimension of the ecological niche for Anolis lizards (or anoles), influencing many aspects of behavior and performance. We hypothesized that urban and natural areas differ in structural habitat, and that this difference would influence perch use by lizards. We compared habitat availability and use by two lizard species (Anolis sagrei and Anolis cristatellus) in four natural and four urban sites in South Florida. We conducted transects to quantify the availability of the structural habitat in urban and natural areas, measuring both natural and artificial substrates, and photographed the canopy to estimate canopy coverage. We compared these availability measures to observations of perch use by lizards in the summer of 2014.

Results/Conclusions

As we predicted, urban areas are structurally quite different than natural areas: they contain broader perches, more horizontal surfaces, and a greater diversity of perch substrates overall. Despite a reduction in the availability of natural perches in urban areas, A. cristatellus preferred natural substrates (i.e., tree trunks), whereas A. sagrei perch use matched the availability of different types of substrate. In urban areas, lizards of both species used broader perches than were available. Anolis sagrei perched lower in urban than in natural areas (females perched lower than males in both habitats), whereas A. cristatellus did not change its perch height in urban areas. We quantified the differences in perch availability between urban and natural areas, and showed that lizards use these habitats in different ways. Perch use change in urban areas may alter the behavior and performance of anoles, for example, the use of smooth, vertical artificial perches such as posts and walls may change the way lizards move on these surfaces. These results also have potential evolutionary implications, as previous studies of Anolis suggest that broader perch diameters select for longer limbs, which perform better on broad substrates. Urban areas, which are growing in size and number worldwide, provide novel habitats for species that can tolerate life in the city, and Anolis lizards expand their structural habitat niche to use these novel substrates.