The sexual behavior of Anura. 6, The mating pattern of Bufo americanus, Bufo fowleri, and Bufo terrestris. American Museum novitates ; no. 1250

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New York City : The American Museum of Natural History
"Three distinct vocalizations are recognized in the male toads, namely, the sex trill, the chirp, and the warning vibration. These calls are seasonal, being most easily elicited at the height of the breeding season. After the season they dsappear in the following order: sex trill first, chirp second, and warning vibration last. 2. In an experimental situation, sexually active male toads do not discriminate at a distance between other males or females but attempt to clasp members of either sex with equal frequency. There is, however, a slight tendency to clasp pairs more frequently than individuals, the clasps in these cases being directed almost entirely to the male of the pair. This preference for pairs is probably due to greater activity on the part of the pairs. 3. The sex-recognition mechanism (discrimination of a male from a female after amplexus is attempted) is found to be very efficient. The mechanism depends almost exclusively on the warning vibration of a male being clasped. These vibrations act as tactual stimuli of the ventral pectoral region and medial surfaces of the forelimbs of the clasping male, causing him to reject the clasp object. Females do not emit these vibrations, and therefore the clasping male maintains amplexus. Relative girths of male and female, relative 'repulsive actions' of both sexes, and the male's chirp are found not to be efficacious in sex recognition. 4. The positions and movements of the male and female during the oviposition are described in detail. 5. Release of the female by the male at the termination of the oviposition follows a severe concave arching of the back of the female, which partially lifts the male off the female. 6. Pseudo-oviposition (oviposition movements without the deposition of eggs) can sometimes be induced in anterior pituitary injected but unovulated females when clasped by males"--P. 13-14.
15 p. : ill. ; 24 cm.
Includes bibliographical references (p. 14-15).