VonBank Jay A, Weegman Mitch D, Link Paul T, Cunningham Stephanie A, Kraai Kevin J, Collins Daniel P, Ballard Bart M
Caesar Kleberg Wildlife Research Institute, Texas A&M University - Kingsville, Kingsville, TX, 78363, USA.
Present Address: U.S. Geological Survey, Northern Prairie Wildlife Research Center, Jamestown, ND, 58401, USA.
Mov Ecol. 2021 Jan 20;9(1):2. doi: 10.1186/s40462-020-00236-4.
Animal movement patterns are the result of both environmental and physiological effects, and the rates of movement and energy expenditure of given movement strategies are influenced by the physical environment an animal inhabits. Greater white-fronted geese in North America winter in ecologically distinct regions and have undergone a large-scale shift in wintering distribution over the past 20 years. White-fronts continue to winter in historical wintering areas in addition to contemporary areas, but the rates of movement among regions, and energetic consequences of those decisions, are unknown. Additionally, linkages between wintering and breeding regions are generally unknown, and may influence within-winter movement rates.
We used Global Positioning System and acceleration data from 97 white-fronts during two winters to elucidate movement characteristics, model regional transition probabilities using a multistate model in a Bayesian framework, estimate regional energy expenditure, and determine behavior time-allocation influences on energy expenditure using overall dynamic body acceleration and linear mixed-effects models. We assess the linkages between wintering and breeding regions by evaluating the winter distributions for each breeding region.
White-fronts exhibited greater daily movement early in the winter period, and decreased movements as winter progressed. Transition probabilities were greatest towards contemporary winter regions and away from historical wintering regions. Energy expenditure was up to 55% greater, and white-fronts spent more time feeding and flying, in contemporary wintering regions compared to historical regions. White-fronts subsequently summered across their entire previously known breeding distribution, indicating substantial mixing of individuals of varying breeding provenance during winter.
White-fronts revealed extreme plasticity in their wintering strategy, including high immigration probability to contemporary wintering regions, high emigration from historical wintering regions, and high regional fidelity to western regions, but frequent movements among eastern regions. Given that movements of white-fronts trended toward contemporary wintering regions, we anticipate that a wintering distribution shift eastward will continue. Unexpectedly, greater energy expenditure in contemporary wintering regions revealed variable energetic consequences of choice in wintering region and shifting distribution. Because geese spent more time feeding in contemporary regions than historical regions, increased energy expenditure is likely balanced by increased energy acquisition in contemporary wintering areas.
动物的运动模式是环境和生理影响的结果，特定运动策略的运动速率和能量消耗受动物栖息的物理环境影响。北美洲的白额雁在生态特征不同的地区越冬，并且在过去20年里越冬分布发生了大规模变化。除了当代越冬地区外，白额雁仍继续在历史越冬地区越冬，但不同地区之间的移动速率以及这些决策对能量的影响尚不清楚。此外，越冬地区和繁殖地区之间的联系通常也不为人所知，并且可能影响冬季期间的移动速率。
我们利用97只白额雁在两个冬季期间的全球定位系统和加速度数据，以阐明其运动特征，在贝叶斯框架下使用多状态模型对区域转移概率进行建模，估计区域能量消耗，并使用总体动态身体加速度和线性混合效应模型确定行为时间分配对能量消耗的影响。我们通过评估每个繁殖区域的冬季分布来评估越冬地区和繁殖地区之间的联系。
白额雁在冬季早期的每日移动距离更大，随着冬季的推进移动距离减少。向当代越冬地区转移的概率最大，而远离历史越冬地区。与历史地区相比，当代越冬地区的能量消耗高出55%，且白额雁在这些地区花费更多时间觅食和飞行。随后，白额雁在其整个先前已知的繁殖分布范围内度过夏天，这表明在冬季不同繁殖来源的个体有大量混合。
白额雁在越冬策略上表现出极大的可塑性，包括向当代越冬地区的高移民概率、从历史越冬地区的高迁出率以及对西部地区的高区域忠诚度，但在东部地区之间频繁移动。鉴于白额雁的移动趋势是朝向当代越冬地区，我们预计其越冬分布向东的转变将持续。出乎意料的是，当代越冬地区更高的能量消耗揭示了越冬地区选择和分布变化所带来的不同能量后果。由于大雁在当代地区比在历史地区花费更多时间觅食，增加的能量消耗可能通过当代越冬地区能量获取的增加而得到平衡。
