Folivory on Islands with and without Insectivorous Lizards: An Eight-Year Study

Abstract

Sea grape (Coccoloba uvifera) leaf damage was measured on 11 islands with diurnal lizards (Anolis sagrei) and on 7 islands without diurnal lizards from 1986 to 1993. Two types of damage were common: scars (necrotic areas) and holes (entirely missing areas). A static measure in 1986 showed that both scar and hole damage tended to be higher on islands without lizards than on islands with lizards, but only the difference in holes was significant. A dynamic measure that followed tagged leaves each year from 1986 to 1993 showed that overall damage was higher on islands without lizards than on islands with lizards. Island area and isolation were not related to leaf damage. Total leaf damage varied substantially among years, and the temporal pattern of scars differed significantly from that of holes. Mortality of tagged leaves varied substantially among years, but it was nearly identical on islands with and without lizards. Overall, this study showed that sea grape on entirely natural islands was affected positively by lizards and to about the same magnitude as in previous experimental studies on a large island.