Morphological traits affect escape behaviour of the Balearic lizards (Podarcis lilfordi) Dror Hawlena 1,* , Valentín Pérez-Mellado 2 , William E. Cooper Jr. 3 Abstract. Escape theory predicts that a prey should start escaping (flight initiation distance = FID) from a predator when the costs of fleeing and the cost staying are equal or until future fitness is maximized. Consequently, prey escape performances and current reproductive asset can affect FID. We tested effects of body condition, morphology, and whether the tail was regenerated or original on FID in the Balearic lizard (Podarcis lilfordi) by ourselves simulating predators. Lizards with better body condition had longer FID and lizards with longer intact tails had shorter FID. Lizards with regenerated tail presented shorter FID than lizards with intact tails. These results suggest that impaired escape performance is counterbalanced by fitness costs of tail regeneration or by alteration of escape behaviour. The weak association between morphology, body condition and FID suggest that escape performances and asset protection have relatively small effect on P. lilfordi escape decisions. Keywords: antipredatory behaviour, escape, flight initiation distance, predation risk, refuge, Squamata. Escape theory predicts that a prey should start to escape from an approaching predator when the costs of fleeing (primarily opportu- nity costs) and not fleeing (due to predation risk) are equal (Ydenberg and Dill, 1986) or until expected fitness is maximized (Cooper and Frederick, 2007). Flight initiation distance (= FID, distance between predator and prey when escape starts) is predicted to be shorter when cost of escaping increases or risk of delaying escape decreases. These predictions have been verified in various taxa (reviewed by Stankowich and Blumstein, 2005) for many environmental factors affecting risk, includ- ing predator approach speed (Cooper, 1997a; Cooper et al., 2003), number and relative attack angles of predators (Cooper, Pérez-Mellado and Hawlena, 2007) proximity of refuge (Cooper, 1997b), and weather conditions (Rand, 1964; Hertz, Huey and Nevo, 1982), as well as fac- tors affecting the costs of fleeing such as loss of feeding and social opportunities (Cooper, 1 - School of Forestry & Environmental Studies, Yale Uni- versity, 370 Prospect St., New Haven, CT 06511, USA 2 - Departamento de Biología Animal, Universidad de Sala- manca, 37071 Salamanca, Spain 3 - Department of Biology, Indiana University Purdue Uni- versity Fort Wayne, Fort Wayne, IN 46805, USA * Corresponding author; e-mail: dror.hawlena@yale.edu 1999, 2000b; Diaz-Uriarte, 1999; Martín, López and Cooper, 2003a; Cooper, Pérez-Mellado and Hawlena, 2006; Cooper and Wilson, 2007). Risks and costs can vary as a consequence of variation in morphological traits and body con- dition of the prey (Stankowich and Blumstein, 2005). Prey that can escape faster or more effi- ciently have lower cost of not fleeing when at a given distance from a predator, but slower max- imum speed might be associated with a change in escape tactics toward greater reliance of cryp- sis due to immobility to avoid being detected and attacked (Cooper et al., 1990). Faster speed alone would predict shorter predicted FID due to lower risk at a given distance, but a switch to greater crypsis would predict shorter FID. In lizards running speed increases as body size and hind limb length increase; tail length is also ex- pected to affect speed (Warner and Shine, 2006; Cooper and Wilson, 2008). Consequently in the absence of change in tactics, escape theory pre- dicts that individuals having greater body length (snout-vent length = SVL) and longer hind limbs will have shorter FID than conspecifics with shorter SVL and limbs. Effects of body condition on FID are diffi- cult to predict because body condition may af- fect both escape ability and initial fitness. Poor body condition associated with decreased speed © Koninklijke Brill NV, Leiden, 2009. Amphibia-Reptilia 30 (2009): 587-592 Also available online - www.brill.nl/amre