Female mouthbrooders adjust incubation duration to perceived risk of predation

The protection of young from predators is an important and costly component of parental care, and this investment should be adjusted to the predation risk for the offspring. Parents are known to fine-tune defence intensity to the perceived need of protection, yet little attention has been paid to individual variation in the duration of brood defence. To optimize parental investment it may be beneficial to prolong brood care when the predation risk for the young is high. We tested whether cichlids of the species Ctenochromis horei adjust mouthbrooding duration to the perceived predation risk of their offspring. After spawning, females were transferred to an experimental tank, where they incubated the clutch either alone or in the presence of a natural predator of young. Females extended their incubation period by 4.3 days on average when the predator was present. During this prolonged incubation, young continued to grow in the femaleʹs buccal cavity. Interspawning interval was longer for females that incubated eggs than for those that did not, although incubation had no long-term negative effects on female condition or egg number or size. Incubating females may thus breed less frequently. Brood care duration should hence be considered as a flexible and potentially costly trait when investigating costs and benefits of parental care.