Table 1.
Environmental determinants of early-life TL (n = 417 individuals)
| Parameter | Estimate (se) | df | t | p |
|---|---|---|---|---|
| Intercept | −0.140 (0.275) | 153.494 | −0.508 | 0.612 |
| Tmax | −0.156 (0.048) | 126.135 | −3.240 | 0.002 |
| Tmin | −0.010 (0.027) | 132.535 | −0.355 | 0.723 |
| Rainfall (rain) | 0.148 (0.159) | 146.331 | 0.931 | 0.354 |
| Season (wet) | 0.109 (0.190) | 124.784 | 0.573 | 0.568 |
| Rainfall (rain) × Tmax | 0.101 (0.047) | 148.023 | 2.168 | 0.032 |
| Season (wet) × Tmax | 0.130 (0.062) | 159.316 | 2.106 | 0.037 |
| Parental provisioning rate | 0.092 (0.048) | 176.522 | 1.932 | 0.055 |
| Prey size | 0.081 (0.175) | 143.359 | 0.464 | 0.644 |
| Territory quality | 0.021 (0.016) | 112.354 | 1.378 | 0.171 |
| Number of helpers: one helper | 0.072 (0.129) | 133.720 | 0.560 | 0.576 |
| two helpers | −0.087 (0.162) | 141.128 | −0.539 | 0.591 |
| three or more helpers | −0.525 (0.186) | 115.972 | −2.830 | 0.006 |
| Sex (male) | 0.204 (0.079) | 344.075 | 2.571 | 0.011 |
| Mass (g) | −0.132 (0.078) | 351.952 | −1.694 | 0.091 |
| Tarsus length (mm) | 0.031 (0.048) | 353.590 | 0.643 | 0.520 |
| Brood size (range 1 to 4) | 0.038 (0.075) | 157.246 | 0.511 | 0.610 |
| Age at sampling (5 to 9 d) | 0.076 (0.067) | 198.481 | 1.132 | 0.259 |
| Blood storage buffer (Longmire’s) | 0.022 (0.233) | 99.179 | 0.095 | 0.925 |
| Variance components (SD) | ||||
| Maternal ID | 0.310 (0.557) | |||
| Nest ID | 0.083 (0.290) | |||
| qPCR run ID | 0.234 (0.484) | |||
| Residual | 0.444 (0.666) | |||
Shown are results from the linear mixed-effects model with TL (z-score transformed) as dependent variable; all continuous explanatory variates were mean centered. Daily maximum (Tmax) and minimum temperature (Tmin) were averaged across the nestling period (from hatching to day seven). Random (intercept only) variance estimates included: maternal ID, nest ID, and qPCR Run ID. Paternal ID was removed from the final model because it explained zero variance. Bold indicates significant predictors (P < 0.05). Model residuals and predictor covariance estimates were examined to confirm that the model assumptions were met. AICc = 1,144.65; including fixed predictors only, R2m = 0.08; including random and fixed predictors R2c = 0.62.