Data from: A test of the green wave hypothesis in omnivorous brown bears across North America

AbstractHerbivorous animals tend to seek out plants at intermediate phenological states to improve energy intake while minimizing consumption of fibrous material. In some ecosystems, the timing of green-up is heterogeneous and propagates across space in a wave-like pattern, known as the green wave. Tracking the green wave allows individuals to prolong access to higher-quality forage. While there is a plethora of empirical support for such behavior in herbivorous taxa, the green wave hypothesis (GWH) is nuanced based on factors such as body morphometrics and digestive capacity. Furthermore, little is known about whether other taxa, such as omnivores, track the green wave. Our objective was to assess whether the GWH can be extended to explain the movements of omnivores. Using GPS collar data from seven populations (n = 127 individuals) of brown bears (Ursus arctos) across their entire North American range, we first tested whether bears tracked the green wave. Using conditional resource selection functions, we found that variation in proxies of vegetative forage quality better-explained movement and habitat selection than proxies of forage biomass in over half of the bears in our study, providing evidence of green wave tracking. Second, we assess factors that explained variation in green wave tracking using linear mixed-effects models. Green wave tracking in brown bears was explained by the variation in availability of green-up within spring home ranges, and how green-up transitioned across those home ranges. Our results demonstrate that the GWH can partially explain movement of a non-migratory omnivorous species, extending the generality of the GWH as a broad predictor of animal space use. The green wave is another resource wave brown bears track, and our findings help predict brown bear space use, which can be used to guide conservation and habitat restoration efforts.
MethodsThis dataset was developed by merging GPS location data from collared grizzly bears with environmental data. See methods section of Bowersock et al. 2023 in Ecography for details. 
Usage notesBoth datasets do not require specific programs or software to open. They are in the comma-delimited format (CSV).

摘要 植食性动物通常会选择处于中等物候状态的植物，以在提升能量摄入的同时减少纤维物质的摄取量。在部分生态系统中，植被返青的时间存在异质性，并以波浪状格局在空间中传播，该现象被称为返青波（green wave）。追踪返青波可使动物延长获取高质量草料的时长。尽管学界已在多个植食类群中积累了大量支持该行为的实证依据，但返青波假说（green wave hypothesis, GWH）的适用细节会因身体形态计量、消化能力等因素而存在差异。此外，学界对杂食类等其他类群是否会追踪返青波仍知之甚少。本研究旨在评估返青波假说是否可用于解释杂食性动物的移动行为。我们利用覆盖北美棕熊（Ursus arctos）整个分布范围的7个种群（共127只个体）的GPS项圈数据，首先检验了棕熊是否会追踪返青波。通过条件资源选择函数分析，我们发现：在本研究超过半数的棕熊个体中，用以表征草料质量的替代变量对其移动与生境选择的解释力，优于用以表征草料生物量的替代变量，这为棕熊追踪返青波提供了实证证据。其次，我们采用线性混合效应模型，评估了解释返青波追踪行为差异的影响因素。结果显示，棕熊的返青波追踪行为可通过春季家域内返青植被的可获得性，以及返青过程在该家域内的空间过渡特征来解释。本研究结果表明，返青波假说可部分解释非迁徙性杂食性物种的移动行为，拓展了该假说作为动物空间利用通用预测因子的普适性。返青波是棕熊追踪的又一类资源波，本研究结果有助于预测棕熊的空间利用模式，可为其保护与生境修复工作提供指导。
方法 本数据集通过将佩戴GPS项圈的棕熊（灰熊）的定位数据与环境数据合并构建而成。具体细节可参见Bowersock等人2023年发表于《Ecography》的方法章节。
使用说明 本数据集无需特定程序或软件即可打开，采用逗号分隔值（CSV）格式存储。