Table 3.
Model (GLMM) estimates of incubation bout length (in minutes) in relation to sex, incubation period, and length of the previous bout with disturbance, presence of radio tag, body mass, culmen length, and start of incubation within the season as confounding variables
| Fixed effects | Estimate | 95% CI | P |
|---|---|---|---|
| (Intercept) | 692.2 | (663.9, 720.5) | <0.0001 |
| Disturbance | 38.9 | (9.4, 68.4) | 0.002 |
| Radio tag | 8 | (−39.8, 55.9) | 1 |
| Culmen | −2.6 | (−20.6, 15.4) | 1 |
| Body mass | −0.9 | (−10.5, 8.7) | 1 |
| Previous bout length | 0.4 | (0.3, 0.6) | <0.0001 |
| Start of incubation | 2.2 | (−1.8, 6.1) | 0.76 |
| Day of incubation | 7.8 | (2.8, 12.8) | 0.0001 |
| Sex (male)a | −50.9 | (−76.3, −25.5) | <0.0001 |
| Sex × Previous bout | −0.1 | (−0.3, 0) | 0.29 |
| Sex × Day of incubation | 2.4 | (−3.5, 8.4) | 0.95 |
| Start of incubation × Day of incubation | 0 | (−0.6, 0.6) | 1 |
| Random effects | Variance | ||
| Nest (intercept) | 2032 | ||
| z-Transformed (day of incubation) | 165 | ||
| Residual | 13 779 |
N = 729 incubation bouts from 39 nests. Fixed effects, except sex, were mean centered (culmen and body mass were centered within each sex). Results of the model without confounding variables are presented in Supplementary Table S3.
aRelative to female.