Unit of Social Ecology, Free University of Brussels, Brussels, Belgium.
PLoS One. 2011;6(10):e26788. doi: 10.1371/journal.pone.0026788. Epub 2011 Oct 26.
Animals adapt their movement patterns to their environment in order to maximize their efficiency when searching for food. The Lévy walk and the Brownian walk are two types of random movement found in different species. Studies have shown that these random movements can switch from a Brownian to a Lévy walk according to the size distribution of food patches. However no study to date has analysed how characteristics such as sex, age, dominance or body mass affect the movement patterns of an individual. In this study we used the maximum likelihood method to examine the nature of the distribution of step lengths and waiting times and assessed how these distributions are influenced by the age and the sex of group members in a semi free-ranging group of ten Tonkean macaques. Individuals highly differed in their activity budget and in their movement patterns. We found an effect of age and sex of individuals on the power distribution of their step lengths and of their waiting times. The males and old individuals displayed a higher proportion of longer trajectories than females and young ones. As regards waiting times, females and old individuals displayed higher rates of long stationary periods than males and young individuals. These movement patterns resembling random walks can probably be explained by the animals moving from one location to other known locations. The power distribution of step lengths might be due to a power distribution of food patches in the enclosure while the power distribution of waiting times might be due to the power distribution of the patch sizes.
动物会根据环境改变它们的运动模式，以便在寻找食物时最大限度地提高效率。在不同物种中，有两种随机运动模式，即 Lévy 游走和布朗运动。研究表明，这些随机运动可以根据食物斑块的大小分布从布朗运动切换到 Lévy 游走。然而，迄今为止，还没有研究分析性别、年龄、支配地位或体重等特征如何影响个体的运动模式。在这项研究中，我们使用最大似然法来检查步长和等待时间分布的性质，并评估这些分布如何受到年龄和性别的影响，在一个十只自由放养的斑狐猴群体中。个体在活动预算和运动模式上差异很大。我们发现个体的年龄和性别对其步长和等待时间的幂律分布有影响。雄性和老年个体的轨迹比雌性和年轻个体的轨迹更长。至于等待时间，雌性和老年个体的长时间静止期比例高于雄性和年轻个体。这些类似于随机游走的运动模式可能可以通过动物从一个地点移动到另一个已知地点来解释。步长的幂律分布可能是由于围栏中食物斑块的幂律分布，而等待时间的幂律分布可能是由于斑块大小的幂律分布。
