Hertel Anne G, Swenson Jon E, Bischof Richard
Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, NO-1430 Ås, Norway.
Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway.
Behav Ecol. 2017 Nov-Dec;28(6):1524-1531. doi: 10.1093/beheco/arx122. Epub 2017 Sep 11.
There is a growing recognition of the role of individual variation in patterns emerging at higher levels of biological organization. Despite the importance of the temporal configuration of ecological processes and patterns, intraspecific individual variation in diel activity patterns is almost never accounted for in behavioral studies at the population level. We used individual-based monitoring data from 98 GPS-collared brown bears in Scandinavia to estimate diel activity patterns before the fall hunting season. We extracted 7 activity measures related to timing and regularity of activity from individual activity profiles. We then used multivariate analysis to test for the existence of distinct activity tactics and their environmental determinants, followed by generalized linear regression to estimate the extent of within-individual repeatability of activity tactics. We detected 4 distinct activity tactics, with a high degree of individual fidelity to a given tactic. Demographic factors, availability of key foraging habitat, and human disturbance were important determinants of activity tactics. Younger individuals and those with higher bear and road densities within their home range were more nocturnal and more likely to rest during the day. Good foraging habitat and increasing age led to more diurnal activity patterns and nocturnal resting periods. We did not find evidence of diel activity tactics influencing survival during the subsequent hunting season. We conclude that individual variation in activity deserves greater attention than it currently receives, as it may help account for individual heterogeneity in fitness and could facilitate within-population niche partitioning that can have population- or community-level consequences.
人们越来越认识到个体差异在生物组织更高层次出现的模式中所起的作用。尽管生态过程和模式的时间配置很重要，但在种群水平的行为研究中，几乎从未考虑过种内个体在昼夜活动模式上的差异。我们使用来自斯堪的纳维亚半岛98只佩戴GPS项圈的棕熊的基于个体的监测数据，来估计秋季狩猎季节前的昼夜活动模式。我们从个体活动记录中提取了7项与活动时间和规律性相关的活动指标。然后，我们使用多变量分析来检验不同活动策略的存在及其环境决定因素，接着使用广义线性回归来估计活动策略在个体内部的重复程度。我们检测到4种不同的活动策略，个体对给定策略具有高度的忠诚度。人口统计学因素、关键觅食栖息地的可用性以及人类干扰是活动策略的重要决定因素。较年轻的个体以及其活动范围内熊和道路密度较高的个体更倾向于夜间活动，白天更有可能休息。良好的觅食栖息地和年龄增长导致更多的日间活动模式和夜间休息时间。我们没有发现昼夜活动策略会影响随后狩猎季节存活率的证据。我们得出结论，活动中的个体差异值得比目前更多的关注，因为它可能有助于解释个体在适应性方面的异质性，并可能促进种群内部的生态位划分，而这可能会产生种群或群落水平的影响。
