Age dependent reproductive effort in great tits

I measured daily energy expenditure (DEE) of great tits raising offspring using doubly labelled water in three different years (1989–1991). Independent of sex, DEE declined with age. Although DEE declined with age, provisioning rate was independent of age in the same data set, and neither did age significantly affect the number and growth of offspring. Data uploaded here include the DEE estimates and other relevant variables used in the accompanying publication (age, year, sex, ambient temperature).