Tolerance of female co-breeders in joint-laying pukeko: the role of egg recognition and peace incentives

► We examined egg fitness consequences of joint laying in cooperatively breeding pukeko, Porphyrio porphyrio melanotus. ► Fewer eggs hatched in joint nests as clutch size increased, reflecting a possible fitness cost to joint laying. ► Females did not retaliate or cease parental care in response to experimental removal of their eggs from joint nests. ► Risk of nest desertion, most likely initiated by the males, may be an indirect cost preventing the evolution of ovicide.