Population density of the tropical lizard Anolis cristatellus in urban and forested habitats after a major hurricane

Abstract

Urbanization, the process whereby natural environments are modified for human habitation, is increasing worldwide. Many species are extirpated from urban settings, but others can survive and thrive in this environment. Few studies have compared population densities between urban and natural sites and none have investigated how hurricanes might interact with urbanization to affect animal species population dynamics in cities, which is crucial in evaluating population persistence in urban habitats. We quantified post-hurricane population dynamics between urban and forest populations of the tropical lizard Anolis cristatellus in paired urban and forest sites across the island of Puerto Rico at 4, 11, and 16 months following Hurricane Maria. Though we lacked pre-hurricane population density data, we expected lower than normal densities after the hurricane and a gradual increase through time. We found that urban population density was lower compared to natural areas across all pairs of sites. In forested areas, we found increases in perch density, likely associated with post-disturbance succession, but urban structural habitats remained relatively constant through time, with most hurricane-damaged vegetation being rapidly removed by humans. The two sites in our study that were most heavily impacted by the hurricane initially doubled in population density, and density continued to increase through our sampling period. Our findings suggest that hurricanes and urbanization can interact to shape population dynamics in lizards. Moreover, urban sites experience constant human modifications. As such, understanding population dynamics of urban species will require careful consideration of the effect of human intervention in these habitats.