Data from: Predicting bird phenology from space: satellite-derived vegetation green-up signal uncovers spatial variation in phenological synchrony between birds and their environment

Population-level studies of how tit species (Parus spp.) track the changing phenology of their caterpillar food source have provided a model system allowing inference into how populations can adjust to changing climates, but are often limited because they implicitly assume all individuals experience similar environments. Ecologists are increasingly using satellite-derived data to quantify aspects of animals' environments, but so far studies examining phenology have generally done so at large spatial scales. Considering the scale at which individuals experience their environment is likely to be key if we are to understand the ecological and evolutionary processes acting on reproductive phenology within populations. Here, we use time series of satellite images, with a resolution of 240 m, to quantify spatial variation in vegetation green-up for a 385-ha mixed-deciduous woodland. Using data spanning 13 years, we demonstrate that annual population-level measures of the timing of peak abundance of winter moth larvae (Operophtera brumata) and the timing of egg laying in great tits (Parus major) and blue tits (Cyanistes caeruleus) is related to satellite-derived spring vegetation phenology. We go on to show that timing of local vegetation green-up significantly explained individual differences in tit reproductive phenology within the population, and that the degree of synchrony between bird and vegetation phenology showed marked spatial variation across the woodland. Areas of high oak tree (Quercus robur) and hazel (Corylus avellana) density showed the strongest match between remote-sensed vegetation phenology and reproductive phenology in both species. Marked within-population variation in the extent to which phenology of different trophic levels match suggests that more attention should be given to small-scale processes when exploring the causes and consequences of phenological matching. We discuss how use of remotely sensed data to study within-population variation could broaden the scale and scope of studies exploring phenological synchrony between organisms and their environment.

关于山雀属（Parus spp.）物种如何追踪其鳞翅目幼虫食物源的物候变化的种群级研究，已构建出可用于推断种群如何适应气候变化的模型系统，但这类研究往往存在局限——其默认所有个体所处的环境均一致。生态学家正日益借助卫星衍生数据量化动物所处环境的特征，但目前针对物候的研究通常仅在大空间尺度上开展。若要理解作用于种群内繁殖物候的生态与进化过程，考虑个体实际感知的环境尺度或将成为关键。本研究利用分辨率为240米的卫星影像时间序列，对一片385公顷的混交落叶林地的植被返青空间差异进行量化。基于13年的观测数据，我们证实：种群层面的冬尺蛾幼虫（Operophtera brumata）盛发期、大山雀（Parus major）与蓝山雀（Cyanistes caeruleus）的产卵时间，均与卫星衍生的春季植被物候存在关联。进一步研究表明，局地植被返青时间能够显著解释种群内山雀繁殖物候的个体差异，且鸟类与植被物候的同步程度在整片林地中呈现显著的空间异质性。橡树（Quercus robur）与榛树（Corylus avellana）密度较高的区域，其遥感植被物候与两种山雀的繁殖物候匹配度最高。不同营养级的物候匹配程度在种群内存在显著差异，这提示在探索物候匹配的成因与后果时，应更多关注小尺度过程。我们讨论了利用遥感数据研究种群内变异，如何能够拓展探究生物与其环境间物候同步性的研究尺度与范围。