Trading heat and food for safety: Costs of predator avoidance in a lizard

I examined the long-term consequences of a trade-off between predation risk and resource acquisition for the garden skink (Lampropholis guichenoti) by rearing hatchlings to maturity in outdoor enclosures covered with snake pr edator scent (mimicking high predator densities) or control scent (mimickin g low predator densities). Open areas provided optimal foraging and basking sites but were covered with scent, whereas retreat sites provided suboptim al foraging and basking opportunities and were not scented. During tile ini tial six months of the experiment, lizards reared in enclosures covered wit h scent from a natural predator became active later in the day, showed redu ced mobility, and selected "safer" substrate microhabitats than did lizards raised in enclosures covered with control scent. These behavioral shifts r educed opportunities to forage and bask for lizards in tile predator-scente d enclosures. During the study, however, lizards from predator-scented encl osures became gradually less responsive to snake chemical cues, and after o ne year there were no differences in the activity patterns and substrate mi crohabitat use of lizards in both treatments. This pattern of behavior is p aralleled by variation in growth rates of lizards. Throughout the study, li zards exposed to predator scent were lighter and shorter than were lizards exposed to control scent. However, this result reflects differential rates of growth by lizards only during the first six months of the experiment. Ne vertheless, lizards that grew slowly early in life, as a consequence of pre dator avoidance, attained smaller body sizes at maturity and produced light er clutch masses and offspring. Thus, predator avoidance tactics employed e arly in a lizard's life can impose long-term fitness costs.