Table 1. Effect of parental age and life history traits on fledgling recruitment during the first 6 years of life.
| Variablea | Estimate (SE) | Fc | P |
| Intercept | −8.75 (2.90) | ||
| Parental age (PA) | 2.29 (0.80) | 8.15 | 0.0044 |
| PA2 | −0.167 (0.055) | 9.43 | 0.0022 |
| Parental breeding experience (PBE) | −0.11 (0.06) | 3.05 | 0.081 |
| Parental age of last reproduction (PALR) | 0.41 (0.22) | 3.71 | 0.054 |
| Parental last reproduction (PLR) | −1.86 (0.78) | 5.63 | 0.018 |
| Fledgling hatch date (FHD) | −0.026 (0.0053) | 23.24 | <0.0001 |
| Cohort recruitment | 4.90 (0.70) | 49.28 | <0.0001 |
| PALR*PA | −0.13 (0.59) | 5.14 | 0.023 |
| PALR*PA2 | −0.0099 (0.038) | 6.93 | 0.010 |
| PLR*PA | 0.23 (0.086) | 7.56 | 0.0060 |
| FHD*PBE | 0.0033 (0.00096) | 11.90 | 0.0006 |
| Parent identity | <0.0001b |
Data from 1601 fledglings, from 358 parents that fledged in 1988 and 1989 were analyzed.
a
Minimal adequate model. The initial model included parental age (linear and quadratic), sex, patrental cohort, cohort recruitment, fledgling hatch date, recruiting age of parent, parental age at last reproduction, and number of parental previous breeding attempts as fixed variables and parental identity and parental cohort as random factors.
b
Statistical significance of random factors was analyzed by restricted likelihood ratio test.
c
Degree of freedom, 1,1589.