Food Supplementation in a Tropical Mainland Anole, Norops Humilis: Effects on Individuals

In this study I investigated how individuals of Norops humilis at a tropical lowland wet—forest site in Costa Rica used energy made available by supplemental feeding. I manipulated prey availability on three experimental plots by attracting arthropods to bits of rotting meat that were replenished weekly. Each experimental plot was paired with an unmanipulated control plot in a block design. Mark—recaputre data were collected on all plots over a 7—mo test period during which I made 9910 observations on 1582 individuals. Home—range size was not affected by food supplementation. Instead, home—range overlap was increased for all combinations of age—sex groups (juveniles, males, and females) except for females relative to other females and juveniles relative to females. Growth of females was not altered by supplemental food. For males, both the shape of the growth curve and the estimate of asymptotic largest size were altered by food supplementation. No difference in body mass relative to length was observed for either males of females. Rate of egg production of females of experimental plots was significantly more rapid than on control plots. Males appeared to shunt extra food energy into growth and females into reproduction. The responses of this mainland anole are similar to responses described for island anoles in that increased juvenile overlap, increased clumping of juveniles, and unchanged home—range sizes were observed. In contrast, the observation of unchanged relative body mass, unchanged female growth rate, and increased egg—production rates in supplentally fed N. humilis differ from observations of island anoles.