Table 1.
Factors affecting the total number of pup feeds by subordinate male helpers during the peak pup-feeding period (pups 35–75 days old). (Observation time refers to the number of hours of observation. Whether the male was natal or an immigrant was used as a proxy for relatedness. Babysitting, digging and raised guarding refer to individual contributions to babysitting (days per period), social digging (bouts per 3 h) and raised guarding (instances per 3 h). Effect and s.e. indicate the predicted effect of each term on contributions to pup-feeding and their standard error. Prolactin had a significant effect on contributions to pup-feeding in the absence of cortisol data only (χ21=8.29, p=0.004, effect=0.067±0.023). Degrees of freedom were 1 in each case.)
| model terms | Wald statistic (χ2) | p-value | effect | s.e. |
|---|---|---|---|---|
| observation time | 12.75 | <0.001 | 0.043 | 0.012 |
| helper number | 6.83 | 0.009 | −0.027 | 0.010 |
| age | 4.18 | 0.041 | −0.0035 | 0.0017 |
| body weight (g) | 1.40 | 0.24 | 0.0041 | 0.025 |
| daily weight gain (g h−1) | 0.03 | 0.87 | 0.054 | 0.045 |
| natal versus immigrant | 1.82 | 0.18 | 0.28 | 0.21 |
| babysitting contribution | 0.42 | 0.52 | 0.026 | 0.025 |
| digging contribution | 0.32 | 0.57 | 0.0025 | 0.012 |
| raised guarding contribution | 3.11 | 0.078 | 0.021 | 0.012 |
| cortisol level | 11.01 | 0.001 | 0.52 | 0.016 |
| prolactin level | 0.03 | 0.87 | 0.0094 | 0.059 |
| testosterone level | 1.64 | 0.20 | −0.00027 | 0.00021 |
| constant | −3.13 |