Table 1.
Summary statistics and modelled relationships between aspects of reproductive performance (brood hatch date or breeding success) and migratory strategy across male (M) and female (F) shags that bred in one or more summers during 2010, 2011 and 2012 combined. Raw mean (±1 standard deviation) hatch date (days since 1 April) and breeding success (number of chicks fledged) of migrant and resident males and females are shown. β is the model‐estimated effect size for migrants vs. residents (with 95% confidence intervals), and p is the probability that the estimated effect could be observed by chance. NI values are the total numbers of individual residents and migrants (not the total number of observations)
| Sex | NI residents | NI migrants | Resident raw mean ±1 SD | Migrant raw mean ±1 SD | β [95% CI] | p | |
|---|---|---|---|---|---|---|---|
| Hatch date | M | 116 | 88 | 40.8 ± 11.7 | 47.0 ± 10.2 | 5.6 [3.3, 7.9] | <.01 |
| F | 104 | 72 | 40.4 ± 9.6 | 46.9 ± 11.0 | 5.5 [2.6, 8.5] | <.01 | |
| Breeding success | M | 119 | 92 | 2.1 ± 1.1 | 1.8 ± 1.1 | −0.20 [−0.35, −0.04] | .01 |
| F | 124 | 100 | 2.0 ± 1.0 | 1.7 ± 1.1 | −0.17 [−0.35, −0.01] | .05 |