[Dataset:] Fine-scale whisker growth dynamics can be used to interpret temporal foraging information from stable isotope signatures. Supporting data and software.

Stable isotope analysis of slow-growing, metabolically inert tissues is a
common method to investigate foraging ecology in migratory animals, as direct
observations of feeding are often not possible. Using tissue growth dynamics
to interpret foraging timelines can maximize the utility of foraging data;
however, applying inappropriate growth models is problematic and high-
resolution growth measurements are seldom made. We used photogrammetry to
repeatedly measure the length of whiskers in 93 follicles over 670 days in a
trained, captive northern elephant seal (Mirounga angustirostris). We
developed and optimized a follicle-specific growth model to describe the
18,000 whisker length measurements. Whiskers from the captive seal exhibited
asymptotic growth that was described by the von Bertalanffy growth function.
Applying the growth model to serially sampled whiskers from four free-ranging,
adult female northern elephant seals resulted in alignment of peaks in δ15N
along the length of whiskers with the breeding haul-out period, when seals
were not feeding. Our study provides a whisker growth model of the highest
resolution for any mammal and is the first to use whisker growth dynamics for
temporal interpretation of isotopic ratios...... Supporting information
includes graphs showing observed and fitted growth trajectories of all 44
whisker follicles analyzed, the fitted growth parameters for each, and the R
source code used for fitting the model. Detailed descriptions of each files
content are provided in the files.

对生长缓慢、代谢惰性的组织开展稳定同位素分析，是研究洄游动物觅食生态学的常用手段，由于直接观察觅食行为往往难以实现，该方法被广泛应用。借助组织生长动力学解读觅食时间线，可最大化觅食数据的应用价值；然而，使用不当的生长模型会引发分析偏差，且高分辨率的生长测量数据极难获取。
本研究针对一只经训练的圈养北象海豹（Mirounga angustirostris），采用摄影测量法在670天内对93个毛囊的胡须长度进行重复测量，累计获得18000组胡须长度观测数据，并据此开发并优化了针对单个毛囊的专属生长模型。
圈养海豹的胡须呈现渐近生长特征，可通过冯·贝塔朗菲生长函数（von Bertalanffy growth function）进行拟合描述。
将该生长模型应用于4只自由活动的成年雌性北象海豹的连续采样胡须后发现，胡须长度方向上的δ15N峰值与繁殖上岸期（此时海豹停止觅食）高度吻合。
本研究构建了当前分辨率最高的哺乳动物胡须生长模型，且首次将胡须生长动力学用于同位素比值的时间维度解读……
补充材料包含所有44个被分析毛囊的实测与拟合生长轨迹图、各毛囊的拟合生长参数，以及用于模型拟合的R语言源代码。各文件的详细内容说明已在对应文件中提供。