Approach distance (flight initiation distance) and escape methods depend on predation risk. I studied escape methods and effects of risk factors (temperature, perch height and orientation, conspicuousness) on approach distance in seven Puerto Rican anoles. Approach distance increased as temperature decreased in Anolis gundlachi Peters, 1876, presumably because of decreasing running speed, but not in other species (probably because of narrow temperature range). Perch height and approach distance varied inversely in four arboreal species that escape upward, positively in two grass–bush species that are more conspicuous when higher and flee downward, and were unrelated in cryptic Anolis stratulus Cope, 1861. Approach distance was shortest in cryptic A. stratulus and shorter intraspecifically in three species for partially concealed lizards and at sites providing more cover in two species. Approach distance was shorter for A. gundlachi on vertical than nonvertical perches, suggesting that ease of escape upward affects assessed risk. Escape behaviours have been proposed to vary among anole ecomorphs. Grass–bush species fled downward as proposed, or horizontally near ground level. Contrary to predictions of escape downward by trunk–ground and upward by trunk–crown anoles, all arboreal species escaped upward. Only trunk anoles were proposed to use squirreling, but species from four ecomorphs did as well.
European birds adjust their flight initiation distance to road speed limits
