In recent years, attention has been focused on the potential of reproduction inhibitors for the possible control of harmful birds (Davis, 1961, 1962; Elder, 1964; Becker, 1966). Elder, in his search for an effective avian oral contraceptive, found that the best results were obtained with a hypocholesterolemic agent, 22,25-diazacholesterol dihydrochloride (compound SC-12937, Searle & Co., Chicago). When this constituted 0·1% of the diet of pigeons for 10 days, ovulation was inhibited for 3 months and impaired for a further 3 to 9 months. The present study was designed to investigate the effects of compound SC-12937 on the pre-incubatory behaviour of Columba livia and to assess the action of the drug on normal testis cytology.
Males and females in two groups, each of