Data from: Identifying demographic and environmental drivers of recruitment and population growth in a cavity nesting sea duck population

Traits with the greatest proportional effects on fitness are typically conserved (Stearns 1992), and traits with larger temporal variation frequently play a dominant role in population dynamics (Cooch et al. 2001). We examined recruitment patterns and population growth in Common Goldeneyes (Bucephala clangula; hereafter goldeneye), using Pradel mark-recapture models from a long-term nest box study (1997-2010). Our objectives were to estimate recruitment (f) and population growth (λ) relative to recruitment origin group (in-situ or unknown), investigate environmental and density dependent effects on these parameters, and evaluate potential immigration patterns. We detected group-specific differences for f (in-situ: 0.47± 0.13 SE, unknown: 0.31 ± 0.04), and the proportion of boxes occupied by goldeneyes the year prior to recruitment had a significant negative effect on recruitment for the in-situ group (β = -1.04; 85% CI -1.29, -0.78), and a positive effect for the unknown group (β = 0.45; 85% CI 0.30, 0.61). The negative box occupancy effect in the year prior to recruitment, when in-situ yearling goldeneyes prospect for potential nest sites, suggests that local nesting densities may limit recruitment of locally hatched females. We identified two competitive models for λ, which averaged 1.04 ± 0.03 and included interactions between recruitment origin group and a linear temporal trend, and the proportion of ducklings marked two years prior. By evaluating all levels of marking effort on λ, we determined that even if all hatched ducklings were marked in a given year, the resulting in-situ λ was consistently lower than all observed population-level λs during the study, indicating that individuals produced outside of study area nest boxes contributed to λ. Though female goldeneyes are considered highly philopatric, our results suggest that female natal and breeding dispersal may be more prevalent than previously thought, and the spatial scale at which these processes occur requires further investigation.

对适合度（fitness）影响比例最大的性状通常是保守的（Stearns 1992），而时间变异度更高的性状往往在种群动态中占据主导地位（Cooch et al. 2001）。我们基于1997-2010年的长期巢箱监测研究数据，运用普拉德尔标记-重捕模型（Pradel mark-recapture models），分析了普通秋沙鸭（Common Goldeneyes，学名*Bucephala clangula*，后文简称秋沙鸭）的种群补充模式与相关参数。本研究的核心目标包括：估算不同补充起源组（本地孵化或来源未知）的补充率（f）与种群增长率（λ），探究环境因子与密度依赖效应对上述参数的影响，并评估潜在的扩散模式。研究结果显示，不同起源组的补充率存在显著组间差异（本地组：0.47±0.13标准误（standard error, SE），未知组：0.31±0.04）；补充前一年的巢箱占用率对本地组补充率具有显著负效应（β=-1.04；85%置信区间（confidence interval, CI）：-1.29~-0.78），而对未知组补充率则具有显著正效应（β=0.45；85%置信区间：0.30~0.61）。当本地孵化的1龄秋沙鸭探查潜在营巢位点时，补充前一年的巢箱占用负效应表明，本地营巢密度可能会限制本地孵化雌鸭的种群补充。我们筛选出两个与种群增长率λ相关的竞争最优模型，其模型平均估计值为1.04±0.03，模型包含补充起源组与线性时间趋势的交互项，以及两年前标记的雏鸭比例这一协变量。通过评估不同标记强度对种群增长率λ的影响，我们发现：即便某一年所有孵化出的雏鸭均被标记，由此计算得到的本地种群增长率仍始终低于研究期间所有观测到的种群水平增长率，这表明研究区域巢箱之外产生的个体对种群增长具有正向贡献。尽管普通秋沙鸭雌鸟被认为具有极强的恋巢性（philopatric），但本研究结果表明，雌鸟的出生扩散（natal dispersal）与繁殖扩散（breeding dispersal）可能比此前认知的更为普遍，且这些扩散过程发生的空间尺度仍需进一步深入研究。