Table 1.

Explanations for the sample sizes used in our analyses. Sample sizes are numbers of individual nests unless otherwise noted.

	sample size
analysis	total	2001	2002	2003	sample size explanation
female identity	223	70	102	51	Only includes females that bred more than once (86 females bred in 2 years, 17 females bred all 3 years)
females in different nest boxes	149	46	69	34	Only includes multiple-breeding females for which each nest was in a different nest box (70 females bred twice in different boxes and nine females bred more than three times but only once in a different box compared to their other nests)
box identity	444	143	157	144	Only includes nest boxes that were used more than once (159 were used twice and 42 were used in all 3 years)
nest boxes with different females	107	31	38	38	Only includes nest boxes that were used more than once by more than one female (three nest boxes were used in all 3 years, two were used in 44 years and 10 nest boxes were used more than once but in only 1 year by a different female)
combined female and nest box identity	148	46	72	30	Only includes females that bred more than once, each time in a nest box that had been or would be used more than once
lay date	516	164	174	178	Only includes nests were the first egg was laid in the first or last third of each season
woodland compartment	803	250	273	280	The full dataset in standardized nest box design
year	803	250	273	280	The full dataset in standardized nest box design (250 of which were in 2001, 273 were in 2002 and 280 were in 2003)
rearing nest similarity	40	18	22	0	The number of females with a measured nest who were reared by a foster mother with a measured nest.
genetic mother similarity	70	29	41	0	The number of females with a measured nest for whom the putative genetic mother had a measured nest. This included both cross-fostered and natal-fostered chicks because we found no relationship between rearing nest size and adult nest size.
lay-change	223	70	102	51	Differences in laying date of nests by repeat breeding females