Table 1.

Overview of the number of daily energy expenditure (DEE) measurements of great tits (Parus major) taken for this study

	Egg 4	Egg 8	Other	Measured twice	Total number of females	Total number of DEE samples
Hoge Veluwe
2008	25	18	7	0	50	50
2009			9	9	9	18
Oosterhout
2008			19	4	19	23
Totals	25	18	35	13	78	91

Egg 4, Egg 8 and Other refer to the periods over which DEE is measured (i.e. for females measured on egg 4 we injected doubly labelled water in the morning the second egg was laid, we collected egg 3 and egg 4 and measured isotope elimination rates between egg 3 and 4 from which DEE was calculated. One egg was laid per day). Only measurements under Egg 4 and Egg 8 were used in the analyses for comparison of early and late females. Measured twice refers to the number of females of which DEE was measured twice during the same laying period