Individual male three-spined sticklebacks in the field, often collected eggs for longer (up to 10 days) than had been reported for sticklebacks in captivity (3-6 days). The probability that a male slopped collecting eggs increased with the number of eggs already present, and possibly with the age of the eggs. Males with nests hidden under a plant were more likely to continue collecting than males with exposed nests. These results are discussed in the light of theoretical considerations that predict when males should stop collecting further eggs. (C) 1999 The Fisheries Society of the British Isles.