Acceleration Data Reveal Highly Individually Structured Energetic Landscapes in Free-Ranging Fishers (Pekania pennanti)

Investigating animal energy expenditure across space and time may provide more detailed insight into how animals interact with their environment. This insight should improve our understanding of how changes in the environment affect animal energy budgets and is particularly relevant for animals living near or within human altered environments where habitat change can occur rapidly. We modeled fisher (Pekania pennanti) energy expenditure within their home ranges and investigated the potential environmental and spatial drivers of the predicted spatial patterns. As a proxy for energy expenditure we used overall dynamic body acceleration (ODBA) that we quantified from tri-axial accelerometer data during the active phases of 12 individuals. We used a generalized additive model (GAM) to investigate the spatial distribution of ODBA by associating the acceleration data to the animals' GPS-recorded locations. We related the spatial patterns of ODBA to the utilization distributions and habitat suitability estimates across individuals. The ODBA of fishers appears highly structured in space and was related to individual utilization distribution and habitat suitability estimates. However, we were not able to predict ODBA using the environmental data we selected. Our results suggest an unexpected complexity in the space use of animals that was only captured partially by re-location data-based concepts of home range and habitat suitability. We suggest future studies recognize the limits of ODBA that arise from the fact that acceleration is often collected at much finer spatio-temporal scales than the environmental data and that ODBA lacks a behavioral correspondence. Overcoming these limits would improve the interpretation of energy expenditure in relation to the environment.

探究动物在时空维度上的能量消耗，可更为细致地揭示动物与周边环境的相互作用机制。此类认知有助于深化我们对环境变化如何影响动物能量收支的认识，对于栖息于或邻近人为改造生境（此类生境的变化往往发生迅速）的动物而言尤为重要。本研究以渔貂（Pekania pennanti）为研究对象，对其家域（home ranges）内的能量消耗进行建模，并探究预测空间格局的潜在环境与空间驱动因子。我们采用总体动态身体加速度（overall dynamic body acceleration, ODBA）作为能量消耗的替代指标，该指标源自12只个体活动时段内的三轴加速度计（tri-axial accelerometer）数据。我们借助广义可加模型（generalized additive model, GAM），将加速度数据与动物的GPS记录点位进行关联，以探究ODBA的空间分布特征。随后，我们将ODBA的空间格局与个体的利用分布（utilization distribution）及生境适宜性（habitat suitability）评估结果进行关联分析。研究结果显示，渔貂的ODBA在空间上呈现显著结构化特征，且与个体利用分布及生境适宜性评估结果存在关联，但我们未能借助所选环境数据实现ODBA的有效预测。本研究结果表明，动物空间利用的复杂性超出预期，而基于重定位数据的家域与生境适宜性相关概念仅能部分捕捉该复杂性。我们建议未来研究应正视ODBA的局限性：一方面，加速度数据的时空采样尺度通常远精细于环境数据；另一方面，ODBA缺乏明确的行为对应性。突破这些局限，将有助于优化动物能量消耗与环境关联的解读工作。