Western Transportation Institute and Department of Ecology, Montana State University, Bozeman, MT 59717, USA.
Conserv Biol. 2013 Aug;27(4):721-30. doi: 10.1111/cobi.12075. Epub 2013 Jun 12.
Wildlife crossing structures are one solution to mitigating the fragmentation of wildlife populations caused by roads, but their effectiveness in providing connectivity has only been superficially evaluated. Hundreds of grizzly (Ursus arctos) and black bear (Ursus americanus) passages through under and overpasses have been recorded in Banff National Park, Alberta, Canada. However, the ability of crossing structures to allow individual and population-level movements across road networks remains unknown. In April 2006, we initiated a 3-year investigation into whether crossing structures provide demographic connectivity for grizzly and black bears in Banff National Park. We collected hair with multiple noninvasive methods to obtain genetic samples from grizzly and black bears around the Bow Valley. Our objectives were to determine the number of male and female grizzly and black bears that use crossing structures; examine spatial and temporal patterns of crossings; and estimate the proportions of grizzly and black bear populations in the Bow Valley that use crossing structures. Fifteen grizzly (7 female, 8 male) and 17 black bears (8 female, 9 male) used wildlife crossing structures. The number of individuals detected at wildlife crossing structures was highly correlated with the number of passages in space and time. Grizzly bears used open crossing structures (e.g., overpasses) more often than constricted crossings (e.g., culverts). Peak use of crossing structures for both bear species occurred in July, when high rates of foraging activity coincide with mating season. We compared the number of bears that used crossings with estimates of population abundance from a related study and determined that substantial percentages of grizzly (15.0% in 2006, 19.8% in 2008) and black bear (17.6% in 2006, 11.0% in 2008) populations used crossing structures. On the basis of our results, we concluded wildlife crossing structures provide demographic connectivity for bear populations in Banff National Park.
野生动物穿越结构是缓解道路导致野生动物种群破碎化的一种解决方案,但它们在提供连通性方面的有效性只是表面上的评估。在加拿大艾伯塔省班夫国家公园,已经记录了数百只灰熊(Ursus arctos)和黑熊(Ursus americanus)通过地下通道和天桥的穿越。然而,穿越结构是否能够允许个体和种群水平在道路网络上进行移动仍然未知。2006 年 4 月,我们开始了一项为期 3 年的研究,以确定穿越结构是否为班夫国家公园的灰熊和黑熊提供了种群连通性。我们使用多种非侵入性方法收集毛发,以获取 Bow 谷周围灰熊和黑熊的遗传样本。我们的目标是确定使用穿越结构的雄性和雌性灰熊和黑熊的数量;检查穿越的时空模式;并估计使用穿越结构的 Bow 谷灰熊和黑熊种群的比例。有 15 只灰熊(7 只雌性,8 只雄性)和 17 只黑熊(8 只雌性,9 只雄性)使用了野生动物穿越结构。在野生动物穿越结构中检测到的个体数量与空间和时间上的穿越次数高度相关。灰熊比狭窄的穿越(例如涵洞)更频繁地使用开放的穿越结构(例如天桥)。两种熊类使用穿越结构的高峰期都出现在 7 月,此时觅食活动的高频率与交配季节相吻合。我们将使用穿越结构的熊的数量与相关研究中种群丰度的估计值进行了比较,并确定了大量的灰熊(2006 年为 15.0%,2008 年为 19.8%)和黑熊(2006 年为 17.6%,2008 年为 11.0%)种群使用了穿越结构。根据我们的结果,我们得出结论,野生动物穿越结构为班夫国家公园的熊种群提供了种群连通性。
Isotopes Environ Health Stud. 2014