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

We estimated the energy expenditures resulting from helping behaviour in th e cooperatively breeding cichlid N. pulcher by measuring the metabolic rate s directly associated with specific social and territory maintenance behavi ours of individual pair males and females, and their helpers, in a respirom eter. In pair males, pair females and helpers, routine metabolism was raise d on average 4.4, 3.8 and 3.6 times, respectively, during agonistic behavio ur. Helpers spent 3.3 and 6.1 times routine metabolism, respectively, on su bmissive 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 sta ndard 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 mainten ance and direct brood care. The behavioural energy budget of helpers was st rongly determined by their submissive behaviour. This serves to maintain th e social status of the helpers within the family hierarchy and may therefor e be regarded as 'paying for staying', which may also be true for direct br ood care and other helper duties. We conclude that the substantial energy e xpenditures associated with helping behaviours are probably partly responsi ble for the reduced growth rates of helpers. This is the first study in whi ch energy expenditures associated with specific helping behaviours have bee n measured in brood care helpers, and it provides the first estimate of tot al behavioural energy expenditure in a cooperatively breeding fish. (C) 199 8 The Association for the Study of Animal Behaviour.