Energetics of cooperative breeding in meerkats Suricata Suricatta

We investigate whether energetic constraints play a role in determining social structure in cooperatively breeding meerkats Suricata suricatta. Energetics may be important at various stages of the reproductive cycle. Peak lactation and peak pup feeding are potentially the most energetically stressful periods for lactating mothers and subordinate helpers, respectively. Here, we review current data on lactation and present additional information on helping behaviour. Daily energy expenditure (DEE) of dominant females, subordinate helpers and pups were not particularly high during peak lactation. However, metabolisable energy intakes of lactating mothers (calculated from isotope-based estimates of offspring milk energy intake) were not significantly different from maximal suggested limits (at around seven times resting metabolic rate). DEEs of lactating mothers also increased with litter size, but decreased with group size. By comparison, during peak pup feeding, DEE values of helpers were not greater than those measured prior to breeding. Nor was there any apparent difference in DEE between "keen' and "lazy" helpers, suggesting that helping may not be energetically costly. These results confirm hypotheses that, in cooperatively breeding societies, breeders have high energy costs, which can be reduced by helpers. However, they do not support the notion that helpers incur substantial energetic costs in raising young. (c) 2004 Elsevier B.V. All rights reserved.