Effects of predation risk factors on escape behavior by Balearic lizards (Podarcis lilfordi) in relation to optimal escape theory

William E. Cooper, Dror Hawlena, Valentín Pérez-Mellado

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33 Scopus citations


Escape theory predicts that flight initiation distance (FID = predator-prey distance when escape begins) increases as predation risk increases. We tested effects of variation of approach speed and directness, predator persistence, concealment, and weather conditions on FID in the Balearic lizard (Podarcis lilfordi) by ourselves simulating predators. We examined effects of directness of approach on probability of fleeing and of repeated approach on entering refuge and distance fled. As predicted, FID was greater for faster approach speed, more direct approach, during second than first approaches, and when lizards were exposed than partially concealed. Other effects of directness of approach and repeated approach also were as predicted by greater assessed risk by the lizards. The proportion of individuals that fled was greater for direct than indirect approaches. The proportion of lizards that entered refuges and distance fled were greater during the second of two successive approaches. Effects of weather on FID were complex. FID was shortest in the warmest conditions with no noticeable wind, when lizards were active. Lizards were inactive and basked in the other conditions. FID was longest at 20°C without wind, and intermediate FID occurred at 18°C in windy conditions. We present hypotheses for weather effects. Tests are needed to unravel effects of temperature and wind speed. All predictions of escape theory for simple risk factors, i.e., all except than weather conditions, were confirmed. Escape theory successfully predicts FID for these risks in P. lilfordi, other lacertids, and more broadly, in ecologically and taxonomically diverse lizards.

Original languageAmerican English
Pages (from-to)99-110
Number of pages12
JournalAmphibia - Reptilia
Issue number1
StatePublished - 1 Feb 2009
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgements. This work was partially supported by grant REN2003 08432 CO2 02 from the Spanish Ministry of Education and Science to V.P.M. and by the Pippert Research Scholar award to W.E.C.


  • Antipredatory behavior
  • Escape
  • Flight initiation distance
  • Predation risk
  • Refuge
  • Squamata


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