Royal Alberta Museum, Government of Alberta, Edmonton, Alberta, Canada.
PLoS One. 2013 Jul 3;8(7):e68130. doi: 10.1371/journal.pone.0068130. Print 2013.
The area traversed in pursuit of resources defines the size of an animal's home range. For females, the home range is presumed to be a function of forage availability. However, the presence of offspring may also influence home range size due to reduced mobility, increased nutritional need, and behavioral adaptations of mothers to increase offspring survival. Here, we examine the relationship between resource use and variation in home range size for female barren-ground grizzly bears (Ursus arctos) of the Mackenzie Delta region in Arctic Canada. We develop methods to test hypotheses of home range size that address selection of cover where cover heterogeneity is low, using generalized linear mixed-effects models and an information-theoretic approach. We found that the reproductive status of female grizzlies affected home range size but individually-based spatial availability of highly selected cover in spring and early summer was a stronger correlate. If these preferred covers in spring and early summer, a period of low resource availability for grizzly bears following den-emergence, were patchy and highly dispersed, females travelled farther regardless of the presence or absence of offspring. Increased movement to preferred covers, however, may result in greater risk to the individual or family.
动物的活动范围大小取决于其对资源的利用程度。对于雌性动物而言，活动范围通常是由觅食资源的丰富度决定的。然而，由于幼崽活动能力下降、营养需求增加以及母亲为提高幼崽成活率而采取的行为适应性调整等因素，幼崽的存在也可能会影响活动范围的大小。本研究以加拿大北极地区麦肯齐三角洲地区的雌性荒地灰熊（Ursus arctos）为研究对象，探讨了其资源利用与活动范围大小变化之间的关系。研究利用广义线性混合效应模型和信息理论方法，开发了一种方法来检验与栖息地异质性低的情况下的栖息地选择有关的活动范围大小假说。研究发现，雌性灰熊的繁殖状态会影响其活动范围大小，但在春季和初夏，对高度选择的栖息地的个体空间可用性则是影响活动范围大小的更强相关因素。如果这些在春季和初夏高度选择的栖息地在资源匮乏的时期（即熊从冬眠中醒来后）是分散且不连续的，那么无论是否有幼崽存在，雌性灰熊都会迁徙到更远的地方。然而，增加对这些偏好栖息地的利用可能会使个体或家庭面临更大的风险。
