Will He Stay or Will He Go? Features of Nest-Guarding Common Gobies Affecting Response to Predation Risk

Individuals of the same species often show consistent differences in behaviour, categorized as personalities. For an animal with parental care, reproductive success may be affected by the behaviour of the parent. When reanalysing a previously published field study, I found that nest-guarding male common gobies, Pomatoschistus microps, showed individual differences in behavioural response to disturbance during simulated predation risk. There was also a difference in nesting success with some nests being abandoned prematurely. The males were tested over a nesting cycle with respect to individual behaviour patterns. Two behaviours were quantified, in the presence of a live eelpout, Zoarces viviparus, behind glass: (1) time away from nest after being evicted by the approach of a finger, and (2) the distance between the finger and the nest when the male escaped from the nest. Of 24 males studied, only half remained in their nest for the whole nesting cycle, while the other nests were abandoned earlier, failing in the current reproductive event. No direct effects of behaviour were found in males that abandoned early or remained at the nest for the full nesting cycle. However, larger males stayed away from the nest for longer and more often abandoned their nests prematurely than smaller males. This may be explained by a better competitive ability to renest for a larger male. Behaviour, but not nesting success, was also connected with brood size. Males with smaller broods stayed away from the nest for longer. Nesting success thus seemed to result from a combination of size and male personality.