Table 2.

Summary statistics and modelled relationships between brood hatch date and breeding success and pair migratory strategy across shag pairs where both the female and male were classified as resident or migrant. The expected numbers of attempts are the frequencies of pair migratory strategies given random pairing. Raw mean (±1 standard deviation) hatch date and breeding success of pairs comprising migrant or resident males and females are shown. β is the model‐estimated effect size for pair migratory strategy, with 95% confidence intervals. Models that included pair migratory strategy as an explanatory factor fitted significantly better than models without this factor (hatch date, LRT, χ² = 147.0, p < .01; breeding success, LRT, χ² = 10.7, p = .05)

Male strategy	Female strategy	No. of attempts	Expected no. of attempts	Hatch date		Breeding success
				Raw mean ±1 SD	β [95% CI]	Raw mean ±1 SD	β [95% CI]
Resident	Resident	35	30	36.6 ± 7.5	37.2 [34.0, 40.6]	2.3 ± 1.0	0.8 [0.62, 1.05]
Resident	Migrant	14	19	48.4 ± 14.5	48.6 [42.7, 54.5]	1.6 ± 1.1	0.5 [0.07, 0.87]
Migrant	Resident	11	16	41.0 ± 8.5	41.0 [34.8, 47.2]	1.6 ± 1.1	0.5 [0.03, 0.95]
Migrant	Migrant	15	10	45.5 ± 9.0	45.6 [40.4, 50.7]	1.6 ± 1.0	0.5 [0.03, 0.87]