A field study of Costa Rican lizards

Abstract

From October 1967 to March 1970 local populations of 26 species of lizards including gekkonids, iguanids, anguids, teiids, and scincids, were studied at 15 localities on 23 study areas in Costa Rica. Capture-mark-recapture procedures were used and the field records were supplemented by examinations of museum specimens. More than 17,000 field records were accumulated, representing tropical and subtropical rain forest, xeric lowland forest, gallery forest along streams, ocean beach, and various transitional situations. The species studied were a spectrum of ecological types; some were euryecic and showed significant ecological change from one study area to another with different habitat or climate. Preferred body temperatures ranged from 19.5°C in Anolis tropidolepis to approximately 40°C in Cnemidophorus deppii. Heliothermic species were found to have the highest body temperatures, Ctenosaura similis and Ameiva undulata maintaining levels only a little below that of Cnemidophorus deppii, and a little higher than the species of Sceloporus. In basilisks, skinks and most kinds of anoles, preferred body temperatures were found to be between 27 and 35.5 °C. Growth to breeding maturity occurred in 4 to 8 months in most kinds of small lizards, but the largest kinds required a longer time—at least a year in Basiliscus basiliscus and 2 years or more in Ctenosaura and Iguana. In most species marked individuals that were recaptured after intervals of a month or more had moved no more than 15 m, and typical home ranges of most species were judged to have radii in the range of 5 to 12 m. Reproductive cycles were found to be closely correlated with climate. In northwestern Costa Rica where there is little precipitation from December to April, most species including Anolis cupreus, A. sericeus, A. intermedins, Ctenosaura similis, Ameiva undulata, Sceloporus variabilis and Cnemidophorus deppii cease to produce eggs in the dry season. In the warm, humid climate of the Caribbean lowlands there is year-round reproduction in most species but its level changes throughout the annual cycle, with more egg-laying in the wetter months and less in the drier months. In Basiliscus vittatus and Scincella chernei changes in the level of reproduction are most prominent; in Anolis humHis at San Miguel de Sarapiqui and Gonatodes albogularis at Limon there is relatively little change in the level of reproduction throughout the year. Most nearly uniform year-round reproduction occurs in Anolis tropidolepis in montane cloud forest in a climate that is cool r.nd moist throughout the year.