The tale of the bad stepfather: male three-spined sticklebacks Gasterosteus aculeatus L. recognize foreign eggs in their manipulated nest by egg cues alone

The ability to discriminate between own and foreign eggs was investigated in brood-caring male three-spined sticklebacks Gasterosteus aculeatus. Males totally cannibalized clutches that contained both foreign and their own eggs significantly more often than sham-manipulated control clutches that only contained their own eggs. These results show that caring males are able to recognize the presence of foreign eggs by egg cues alone.