BREEDING BIOLOGY OF THE GREAT-PLAINS TOAD IN OKLAHOMA

Over a five year period, breeding biology of the Great Plains toad (Bu fo cognatus) was studied in central Oklahoma. Breeding activity was cl osely associated with precipitation. Consequently, the number of night s when breeding occurred during spring varied considerably from year t o year. Breeding occurred for 14 consecutive nights during March 1985, up to six consecutive nights after rainstorms in April and early May but for only one or two nights after June rains. Breeding activity was greatest during the first three hours after sunset and typically duri ng the first two nights after a rainstorm. Regardless of when females entered the breeding pool and paired, egg laying began at sunrise and lasted until midmorning with amplexus averaging 803 minutes. Bufo cogn atus exhibited communal egg laying at seven different breeding sites t hat characteristically had large breeding choruses. Eighty-eight perce nt of all females in those pools laid eggs at a 1 m(2) to 4 m(2) area specific in each pool. These areas were used from rain to rain and fro m year to year. It is not clear why these exact locations were repeate dly chosen or why communal egg laying was so prevalent. Females exhibi ted size-related fecundity with clutches ranging from 1342-45,054 eggs . Larval period also varied greatly ranging from 45 days in April to 1 8 days in June. Finally, mean size of breeding males and females incre ased markedly over the course of the 1985 breeding season and individu ally marked adults captured over three years exhibited a wide range of growth rates.