Stimulus Determinants of Sexual and Aggressive Behavior in Male Domestic Fowl1)

Abstract

Stimulus factors eliciting sexual and aggressive responses in New Hampshire and Barred Plymouth Rock males were analyzed by tests with models and live females of several breeds. Sexual morphology was not a factor in response to the models. Postural position was important. Models in the crouching position did not elicit aggressive responses. Sexual responses were elicited by all models (male, female, crouching, aggressive stance, normal standing position) but the crouched models were most effective. Raised hackles on standing models tended to depress aggressive responses. The cocks were clearly differentiated into model reactors and non-reactors with most cocks failing to react. In general, model reactors were also more responsive to live females than non-reactors with the differences greatest with white females and with other-breed females in a choice situation involving own-breed hens. Group testing was. a reliable procedure for distinguishing reactors and non-reactors. Males reared in single-breed flocks were more responsive to own-breed females than to other breeds with the fewest responses to females. The low responsiveness of the cocks to the models was interpreted as reflecting the White Leghorn characteristics of the models rather than the absence of liveness. Six males reared in isolation from other birds waltzed only to female chickens, but were never observed to mount a crouching female. After further experience three of these males mounted and copulated by forced matings with standing females rather than mounting females already crouching. One male mated biologically inappropriate stimulus objects and was not observed to copulate with a female. Females reared in isolation crouched to humans but did not respond to the waltzing of cocks. Hackle raising is interpreted as a threat display with both releaser and inhibitory functions and waltzing is tentatively interpreted as a specifically courtship oriented pattern released in the inexperienced male by the female fowl only.