Data from: Delayed timing of breeding as a cost of reproduction

Timing of breeding is a trait with considerable individual variation, often closely linked to fitness because of seasonal declines in reproduction. The drivers of this variation have received much attention, but how reproductive costs may influence the timing of subsequent breeding has been largely unexplored. We examined a population of northern wheatears Oenanthe oenanthe to compare three groups of individuals that differed in their timing of breeding termination and reproductive effort to investigate how these factors may carry over to influence reproductive timing and reproductive output in the following season. Compared to females that bred successfully, females that put in less effort and terminated breeding early due to nest failure tended to arrive and breed earlier in year 2 (mean advancement = 2.2 and 3.3 d respectively). Females that spent potentially more effort and terminated breeding later due to production of a replacement clutch after nest failure, arrived later than other females in year 2. Reproductive output (number of fledglings) in year 2 differed between the three groups as a result of group-level differences in the timing of breeding in combination with the general seasonal decline in reproductive output. Our study shows that the main cost of reproduction was apparent in the timing of arrival and breeding in this migratory species. Hence, reproductive costs can arise through altered timing of breeding since future reproductive success (including adult survival) is often dependent on the timing of breeding in seasonal systems.data for analysis of arrival date in year 2, Costs of reproductiondata for analysis of arrival date in year 2, data collected in the field during a long-term population monitoring project, data set compiled from original data which are stored in Excel files, description of variables (column headings) can be found in the ReadMe fileyear2_ArrivalDate_jav00623.txtdata for analysis of egg laying date in year 2, Cost of reproductiondata for analysis of egg laying date in year 2, data collected in the field during a long-term population monitoring project, data set compiled from original data which are stored in Excel files, description of variables (column headings) can be found in the ReadMe fileyear2_EggLayDate_jav00623.txtdata for analysis of the interval between arrival date and egg laying date in year 2, Cost of reproductiondata for analysis of the interval between arrival date and egg laying date in year 2, data collected in the field during a long-term population monitoring project, data set compiled from original data which are stored in Excel files, description of variables (column headings) can be found in the ReadMe fileyear2_ArrBreedInterval_jav00623.txtdata for analysis of the number of fledglings produced in year 2, Cost of reproductiondata for analysis of the number of fledglings produced in year 2, data collected in the field during a long-term population monitoring project, data set compiled from original data which are stored in Excel files, description of variables (column headings) can be found in the ReadMe fileyear2_Fledglings_jav00623.txtdata for analysis of female survival to year 2, Cost of reproductiondata for analysis of female survival to year 2, data collected in the field during a long-term population monitoring project, data set compiled from original data which are stored in Excel files, description of variables (column headings) can be found in the ReadMe fileyear2_Survival_jav00623.txtdata for analysis of four fitness parameters in year 1, Cost of reproductiondata for analysis of four fitness parameters in year 1, data collected in the field during a long-term population monitoring project, data set compiled from original data which are stored in Excel files, description of variables (column headings) can be found in the ReadMe filewithin_season_jav00623.tx