EFFECTS OF CHEMICAL AND VISUAL EXPOSURE TO ADULTS ON GROWTH, HORMONES, AND BEHAVIOR OF JUVENILE GREEN IGUANAS

For 1 year, groups of juvenile male green iguanas (Iguana iguana) were housed such that one group was visually exposed to an adult female, a second group was both visually and chemically exposed to an adult fem ale, a third group was visually exposed to an adult male, and a fourth group was both visually and chemically exposed to an adult male. Juve nile males exposed to signals from adult males showed signs of chronic stress, including reduced growth rates, lower testosterone levels, hi gher corticosterone levels, and decreased frequencies of headbob displ ay. Although visual exposure alone was sufficient to suppress growth, testosterone levels, and rates of display, the addition of chemical ex posure strengthened some of these effects. Both chemical and visual ex posure to an adult male were necessary to produce elevated corticoster one levels. In contrast, juvenile males exposed to visual and chemical signals from an adult female exhibited growth rates, hormone levels, and behavior patterns typical of juvenile males housed in the absence of adults of either sex. These results suggest that visual and chemica l signals from dominants may serve to reinforce social relationships a mong males through their influence on the physiology and behavior of r eceivers.