PARENTAL BEHAVIOR IN RELATION TO THE OCCURRENCE OF SNEAKING IN THE COMMON GOBY

To investigate whether male common gobies, Pomatoschistus microps (Pis ces, Gobiidae), treat their offspring differently depending on confide nce of paternity, we conducted an experiment in which randomly chosen males either spawned alone with a female, or with a sneaking male pres ent. Males did not treat their brood differently whether they had expe rienced sneaking or not. Our estimates of parental care, nest defence against potential egg predators and fanning rate were the same for the two treatments. Furthermore, there was no difference in filial cannib alism (eating their own progeny) between males that had been sneaked u pon and males that had not. However, nest-guarding males that ate some of their brood had a smaller original brood area than other males. Th is suggests either an increase in paternal expenditure with increased brood size or a threshold value (absolute brood size or proportion of nest space covered) above which males do not cannibalize eggs. (C) 199 8 The Association for the Study of Animal Behaviour.