Testosterone and sex-related behavior and morphology: Relationship during maturation and in the adult Japanese Quail

Abstract

Hormonal, behavioral, and morphological aspects of reproduction were monitored in maturing and in adult male Japanese Quail. In Experiment I, animals were observed daily for crowing, tested for mating, and measured for cloacal gland area. Blood samples were taken on the day the animal first crowed and on the day the animal first mated. Animals initiated crowing significantly earlier than mating (Day 32 vs. Day 35, respectively; P < .05). The concentration of testosterone and the cloacal gland area increased significantly between the onset of crowing and mating ( p < .01). In the second experiment, animals were observed, tested, and sampled between 36 and 94 days of age. Hormonal, behavioral, and morphological variables increased rapidly in time to reach a maximum about which subsequent values oscillated. Attainment of these maxima followed the sequence observed at the onset of sexual behavior and increases in serum testosterone and cloacal gland area. All variables were highly positively correlated in time. Maxima were attained at 44 days for testosterone concentrations, 49 days for crowing, 50 days for cloacal gland area, 52 days for mating attempts, and 81 days for cloacal contacts. This similar sequence in the onset and maxima of sex-related hormonal, behavioral, and morphological characteristics implies a differential activation of target areas which regulate these variables.