Behavioural time-energy budgets of cooperatively breeding Neolamprologus pulcher (Pisces: Cichlidae)

We estimated the energy expenditures resulting from helping behaviour in the cooperatively breeding cichlid N. pulcher by measuring the metabolic rates directly associated with specific social and territory maintenance behaviours of individual pair males and females, and their helpers, in a respirometer. In pair males, pair females and helpers, routine metabolism was raised on average 4.4, 3.8 and 3.6 times, respectively, during agonistic behaviour. Helpers spent 3.3 and 6.1 times routine metabolism, respectively, on submissive behaviour (tail quivering) and digging. These estimates of energy expenditure were combined with laboratory time budgets, obtained previously, to calculate behavioural time-energy budgets for pair members and helpers. Both groups spent on average 98.5% of total metabolism on routine and standard metabolism. With regard to the energy expended on specific behaviours, pair males invested almost exclusively in intrafamily agonistic behaviour, while pair females and helpers shared the investment in territory maintenance and direct brood care. The behavioural energy budget of helpers was strongly determined by their submissive behaviour. This serves to maintain the social status of the helpers within the family hierarchy and may therefore be regarded as 'paying for staying', which may also be true for direct brood care and other helper duties. We conclude that the substantial energy expenditures associated with helping behaviours are probably partly responsible for the reduced growth rates of helpers. This is the first study in which energy expenditures associated with specific helping behaviours have been measured in brood care helpers, and it provides the first estimate of total behavioural energy expenditure in a cooperatively breeding fish. (c) 1998 The Association for the Study of Animal Behaviour.