Foraging performance is widely hypothesized to play a key role in shaping age-specific demographic rates in wild populations, yet the underlying behavioral changes are poorly understood. Seabirds are among the longest-lived vertebrates, and demonstrate extensive age-related variation in survival, breeding frequency and success. The breeding season is a particularly critical phase during the annual cycle, but it remains unclear whether differences in experience or physiological condition related to age interact with the changing degree of the central-place constraint in shaping foraging patterns in time and space. Here we analyze tracking data collected over two decades from congeneric black-browed (BBA) and grey-headed (GHA) albatrosses, Thalassarche melanophris and T. chrysostoma, breeding at South Georgia. We compare the foraging trip parameters, at-sea activity (flights and landings) and habitat preferences of individuals aged 10–45 years and contrast these patterns between the incubation and early chick-rearing stages. Young breeders of both species showed improvements in foraging competency with age, reducing foraging trip duration until age 26. Thereafter, there were signs of foraging senescence; older adults took gradually longer trips, narrowed their habitat preference (foraging within a smaller range of sea surface temperatures) (GHA), made fewer landings and rested on the water for longer (BBA). Some age-specific effects were apparent for each species only in certain breeding stages, highlighting the complex interaction between intrinsic drivers in determining individual foraging strategies. Using cross-sectional data, this study highlighted clear age-related patterns in foraging behavior at the population-level for two species of albatrosses. These trends are likely to have important consequences for the population dynamics of these threatened seabirds, as young or old individuals may be more vulnerable to worsening environmental conditions.

中文翻译：

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年龄对两种密切相关的信天翁觅食行为的影响。

人们普遍假设觅食性能在塑造野生种群中特定年龄的人口统计率方面发挥关键作用，但人们对潜在的行为变化知之甚少。海鸟是寿命最长的脊椎动物之一，在生存、繁殖频率和成功率方面表现出广泛的与年龄相关的变化。繁殖季节是年度周期中特别关键的阶段，但尚不清楚与年龄相关的经验或生理条件的差异是否与形成时空觅食模式的中心位置约束的变化程度相互作用。在这里，我们分析了二十年来从南乔治亚州繁殖的同属黑眉 (BBA) 和灰头 (GHA) 信天翁、Thalassarche melanophris 和 T. chrysostoma 收集的跟踪数据。我们比较觅食行程参数，海上活动（飞行和着陆）和 10-45 岁个体的栖息地偏好，并对比孵化和早期雏鸡饲养阶段的这些模式。随着年龄的增长，这两个物种的年轻育种者的觅食能力都有所提高，直到 26 岁的觅食行程持续时间缩短。此后，有觅食衰老的迹象；老年人逐渐进行更长的旅行，缩小他们的栖息地偏好（在较小的海表温度范围内觅食）（GHA），减少登陆并在水面上休息更长时间（BBA）。某些特定年龄的影响仅在某些育种阶段对每个物种都很明显，突出了确定个体觅食策略的内在驱动因素之间的复杂相互作用。使用横截面数据，这项研究强调了两种信天翁在种群水平上觅食行为的明显年龄相关模式。这些趋势可能会对这些受威胁海鸟的种群动态产生重要影响，因为年轻人或老年人可能更容易受到环境条件恶化的影响。