Breeding site fidelity of adult P. lydia was studied at a small pond in central coastal California. Both males and females returned in equal proportions following marking. No morphological or behavioural differences were detected between males that dispersed and those not observed to disperse. Male dispersal occurred primarily soon after capture and among relatively old males that were at or near the end of their reproductive lifespan. These latter individuals often wandered widely, but only rarely obtained matings. Transplanted males disappeared more frequently after marking than individuals not transplanted; however, those observed again were as likely to remain at the pond to which they were transplanted as were marked, untransplanted residents. The results indicate that adult dispersal in this species during the reproductive period is small.