Figure 1.
Differences in maternal provisioning rate in the presence of helpers and potential mechanisms. (a) Mothers provisioned their brood at a significantly reduced rate in the presence of helpers (two-sample t-test, t15=3.28, p=0.005). (b) Two potential mechanisms are larger group sizes (two individuals in pairs versus more than two in groups) and greater carer : offspring ratios in the presence of helpers (Mann–Whitney U-test, W=84, N=12, 8, p=0.0008). Figures show means±s.e. (except for group size in pairs, which is always two individuals).