Abstract
We tested black iguanas' (
Ctenosaura similis
) discrimination of risk from a person who walked toward them vs. by them (1, 2, or 3 m distant). Study groups varied in exposure to humans (heavy, minimal, or none). As an experimenter approached, iguanas moved, ran, or remained still. Over 80% of variation in the person's distance when the iguana moved is explained by human exposure, approach angle, animal size, and amount of tail regenerated (after loss to predators). Distance to move was less for tangential than for direct approaches. Iguanas with heavy exposure distinguished between direct and all tangential approaches, whereas those with no exposure distinguished direct and 1-m approaches from 2- and 3-m approaches. Distance to move was inversely related to human exposure. Body size did not differ for groups and was correlated with distance to move (larger animals ran sooner). Iguanas habituate to humans but continue to assess potential danger.