The dangers of life in the city: patterns of activity, injury and mortality in suburban lizards (Tiliqua scincoides)

Human activities affect animal populations whenever animals and humans live in close proximity, but patterns of mortality in urban wildlife remain poorly known. We analyzed rates of injury and mortality of bluetongue lizards (Tiliqua scincoides) in Sydney, Australia, using a Wildlife Information and Rescue Service database that contained more than 2000 reported "rescues" of this species over a three-year period. Motor vehicles and dogs killed many adult lizards in springtime (the mating season) when adult males move about more frequently. Domestic cats killed mainly juvenile lizards, especially just after parturition in midsummer. Weather conditions affected rescue rates, presumably because lizards were more active on hot dry days. Habitat loss was the most important cause for lizard rescue in highly urbanized areas, whereas domestic pets were a major threat in outlying suburbs. Such datasets are subject to many biases but allow meaningful comparisons at some levels of analysis. The large datasets of wildlife rescue groups have considerable potential to illuminate the nature and frequency of interactions between humans and wildlife.