Data from: On the importance of having a good mother: maternal investment affects duckling mortality risk in wood ducks

Most avian populations experience more variation in recruitment than adult survival, and twhich drives much of the change in population growth rates from year to year. In duck species, the probability of duckling survival is an important component of recruitment into the breeding population. We investigated how variation in maternal investment in offspring by nesting female wood duck Aix sponsa affected duckling mortality (1‐survival) to 60 days of age using capture‐mark‐recapture techniques. Our primary sample consisted of 3,035 ducklings, from 545 nests, that were marked with uniquely coded webtags on the day of hatch over nine nesting seasons (2008‐2016). We also included 4,437 HY and AHY individuals to increase precision on parameter estimates because some ducklings were not recaptured until after fledging. Duckling mortality was greatest during the first week of life (0.76, 85% C.I. 0.71, 0.81) and approached zero by the second week after hatching (0.005, 85% C.I. 0, 0.025). We observed a quadratic effect of hatch date on duckling mortality (βHD = 0.013, 85% CI 0.13, 0.20, βHD2 = 0.12, 85% CI 0.051, 0.017) of hatch date, suggesting that successful females improve fitness by nesting early in the year, but not too early (15 days before mean hatch). Increased egg volume and duckling mass reduced the probability of ducking mortality (βegg volume = ‐0.155, 85% CI ‐0.245, ‐0.075. βduckling mass = ‐7.56, 85% CI ‐10.67,‐4.45). Our results suggest that risk of mortality for ducklings is influenced, at least in part, by maternal effects, which are manifested through energy allocation and behavior during the breeding season. As such, individual heterogeneity among breeding females affects duckling mortality risk and likely the recruitment process for wood ducks.

多数鸟类种群的补充量（recruitment）变异程度高于成体存活率，而补充量变异是驱动种群增长率年际波动的核心因素。
在鸭类物种中，雏鸭存活率是繁殖种群补充过程的重要组成部分。
本研究采用标记重捕法（capture-mark-recapture），探究筑巢雌性林鸳鸯（Aix sponsa）的子代母源投资（maternal investment）变异如何影响雏鸭至60日龄的死亡率（即1减存活率）。
本研究的核心样本涵盖2008至2016年共9个繁殖季的545个巢中的3035只雏鸭，所有雏鸭均在孵出当日佩戴带有唯一编码的翼网标（webtag）。
此外，为提升参数估计精度，本研究还纳入了4437只当年孵化个体（HY, Hatch Year）与隔年孵化个体（AHY, After Hatch Year）——因部分雏鸭直至离巢后才会被重捕。
雏鸭死亡率在孵出后第一周达到峰值（0.76，85%置信区间（confidence interval, CI）：0.71~0.81），至第二周时便趋近于0（0.005，85%CI：0~0.025）。
本研究发现孵卵日期对雏鸭死亡率存在二次效应（β_HD=0.013，85%CI：0.13~0.20；β_HD²=0.12，85%CI：0.051~0.017），这表明繁殖成功的雌性个体通过在年度繁殖季早期筑巢可提升自身适合度（fitness），但不宜过早（较平均孵卵日期提前15天左右）。
卵体积与雏鸭体重的增加均会降低雏鸭死亡率（β_卵体积=-0.155，85%CI：-0.245~-0.075；β_雏鸭体重=-7.56，85%CI：-10.67~-4.45）。
本研究结果表明，雏鸭的死亡风险至少部分受到母源效应（maternal effects）的调控，而该效应通过繁殖季的能量分配与行为表现出来。
因此，繁殖雌性个体间的异质性会影响雏鸭的死亡风险，并进而影响林鸳鸯的种群补充过程。