Pronounced Fidelity and Selection for Average Conditions of Calving Area Suggestive of Spatial Memory in a Highly Migratory Ungulate
Pronounced Fidelity and Selection for Average Conditions of Calving Area Suggestive of Spatial Memory in a Highly Migratory Ungulate
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DOI：
10.3389/fevo.2020.564567
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发表时间：
2020-11-23
影响因子：
3
通讯作者：
Kielland, Knut
中科院分区：
文献类型：
--
作者：
Cameron, Matthew D.;Joly, Kyle;Kielland, Knut
许多迁徙动物的一个显著特征是它们每年春天返回不同的产犊（分娩）地区，然而，导致这种模式的迁徙过程中所采用的导航机制尚不清楚。有效地保护这些物种需要可靠地划定这些区域，量化影响它们选择的因素，并了解导致使用产犊区域的潜在机制。我们以贫瘠的地面驯鹿（Rangifer tarandus granti）为研究物种，并利用2010-2017年的GPS项圈数据确定了阿拉斯加西部北极牧群的产犊地点。我们通过比较所有年份组合的空间划分来评估产犊区域的可变性。为了了解景观尺度下的产犊区域选择，我们进行了资源选择分析，将产犊地点与整个鹿群范围内的可用地点进行比较，并结合了时变的遥感植被质量和数量指标。我们发现，尽管产犊区域每年都在变化，但这种年度变化集中在一个反复出现的吸引力区域，这与过去60年的研究一致。产犊地点的特征是平均产犊时间的优质饲料，而不是当年的产犊高峰，并且受不同地理因素的影响范围窄。根据我们的预测模型，每年的产犊地点都位于高于平均水平的地区。我们的研究结果表明，怀孕雌性的春季迁徙模式是迁移到常年平均提供高质量饲料的地区，然后在到达这个产犊地后，利用它们对环境随机性驱动的每年变化的条件的感知来优化选择。我们认为，北美驯鹿对产犊地忠诚的广泛模式支持了基于空间记忆的大尺度导航机制，以优化其在关键生活史阶段的觅食和能量获取。迁徙者依靠记忆到达春季目的地的程度影响了种群对气候变化和人类影响的适应性。
A distinguishing characteristic of many migratory animals is their annual return to distinct calving (birthing) areas in the spring, yet the navigational mechanisms employed during migration that result in this pattern are poorly understood. Effective conservation of these species requires reliable delineation of such areas, quantifying the factors that influence their selection, and understanding the underlying mechanisms resulting in use of calving areas. We used barren-ground caribou (Rangifer tarandus granti) as a study species and identified calving sites of the Western Arctic Herd in Alaska using GPS collar data from 2010-2017. We assessed variability in calving areas by comparing spatial delineations across all combinations of years. To understand calving area selection at a landscape scale, we performed a resource selection analysis comparing calving sites to available locations across the herd's range and incorporated time-varying, remotely sensed metrics of vegetation quality and quantity. We found that whereas calving areas varied from year to year, this annual variation was centered on an area of recurring attraction consistent with previous studies covering the last six decades. Calving sites were characterized by high-quality forage at the average time of calving, but not peak calving that year, and by a narrow range of distinct physiographic factors. Each year, calving sites were located on areas of above-average conditions based on our predictive model. Our findings indicate that the pattern of spring migration for pregnant females was to migrate to areas that consistently provide high-quality forage when averaged across years, and then upon arriving at this calving ground, refine selection using their perception of annually varying conditions that are driven by environmental stochasticity. We suggest that the well-documented and widespread pattern of fidelity to calving grounds by caribou is supportive of a navigational mechanism based on spatial memory at a broad scale to optimize foraging and energy acquisition at a critical life-history stage. The extent to which migrants depend on memory to reach their spring destinations has implications for the adaptability of populations to changing climate and human impacts.