Howarth Chloe R, Bishop Christine A, Larsen Karl W
Environmental Science Program, Thompson Rivers University, Kamloops, British Columbia, Canada.
Science and Technology Branch, Environment and Climate Change Canada, Delta, British Columbia, Canada.
Mov Ecol. 2025 Jul 28;13(1):54. doi: 10.1186/s40462-025-00586-x.
Studies on movement behaviour and habitat use are central to understanding the ecology of migratory animals and play an important role in the conservation and management of these species. However, individuals' spatial ecology can vary substantially, and failing to understand differences within or between populations may be problematic. In British Columbia, Canada, where Western Rattlesnakes reach their northern range limit, individuals undertake seasonal migrations between communal hibernacula and summer hunting grounds. Western Rattlesnakes commonly are associated with low-elevation grasslands and open Ponderosa pine habitats; however, recent work has shown that some animals undertake longer-distance migrations into higher-elevation Douglas-fir forests.
To further investigate multi-phenotypic migratory tactics and habitat use, we compiled all available raw data from radio-telemetry studies conducted on adult males (n = 139) between 2005 and 2019 from nine study sites across the Canadian range of Western Rattlesnakes. We quantify variation in migration distance, timing, altitudinal migration, home range sizes, and destination habitats used across our sample, and we use a linear mixed-modelling approach to assess potential drivers of long-distance migration.
On average, snakes migrated 1364 ± 781 m (ranging from 105 m to 3832 m) from their overwintering dens. Migratory distance differed significantly between sites and was higher among individuals using forests as their migratory destination, yet within-habitat variation was high, suggesting a continuum of migratory phenotypes. Migratory distance was best predicted by two top models: terrain and combined effects (including terrain, physiology, and vegetation factors). Even these top-performing models, however, left much of the variation in migratory distance unexplained (r = 0.65 and 0.64 respectively based on k-fold cross-validation where k = 10), suggesting other factors not measured here, such as genetics and prey quality, may also be contributing.
Overall, this study provides critical knowledge on the movement ecology of a far-ranging reptile with implications for the conservation and management of the species in the far north where seasonal movements are commonplace. Our results shed light on some drivers of multi-phenotypic migration in a taxonomic group where this phenomenon has largely been unstudied, while contributing more broadly to a growing body of literature on migratory variation in animals.
对运动行为和栖息地利用的研究是理解迁徙动物生态学的核心内容，在这些物种的保护和管理中发挥着重要作用。然而，个体的空间生态学可能存在很大差异，未能理解种群内部或种群之间的差异可能会带来问题。在加拿大不列颠哥伦比亚省，西部响尾蛇分布到其北部范围极限，个体在公共冬眠场所和夏季狩猎地之间进行季节性迁徙。西部响尾蛇通常与低海拔草原和开阔的黄松栖息地相关联；然而，最近的研究表明，一些个体进行更长距离的迁徙，进入高海拔的花旗松森林。
为了进一步研究多表型迁徙策略和栖息地利用情况，我们汇总了2005年至2019年间在加拿大西部响尾蛇分布范围内的九个研究地点对成年雄性（n = 139）进行的无线电遥测研究的所有可用原始数据。我们量化了样本中迁徙距离、时间、海拔迁徙、家域大小和使用的目的地栖息地的变化，并使用线性混合建模方法评估长途迁徙的潜在驱动因素。
平均而言，蛇从它们的越冬洞穴迁徙了1364 ± 781米（范围从105米到3832米）。不同地点之间的迁徙距离差异显著，以森林为迁徙目的地的个体迁徙距离更高，但栖息地内部的变化也很大，这表明存在连续的迁徙表型。迁徙距离由两个顶级模型最佳预测：地形和综合效应（包括地形、生理和植被因素）。然而，即使是这些表现最佳的模型，也有很大一部分迁徙距离的变化无法解释（基于k折交叉验证，k = 10时，r分别为0.65和0.64），这表明这里未测量的其他因素，如遗传学和猎物质量，也可能有影响。
总体而言，本研究提供了关于一种分布广泛的爬行动物运动生态学的关键知识，对该物种在季节性运动很常见的遥远北方的保护和管理具有重要意义。我们的研究结果揭示了一个分类群中多表型迁徙的一些驱动因素，而该现象在很大程度上尚未得到研究，同时更广泛地为关于动物迁徙变化的不断增长的文献做出了贡献。
