Monitoring Department, Swiss Ornithological Institute, Seerose 1, Sempach, CH-6204, Switzerland.
Department of Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis, OR, 97331, U.S.A.
Conserv Biol. 2021 Aug;35(4):1256-1267. doi: 10.1111/cobi.13676. Epub 2021 Mar 8.
Globally, anthropogenic land-cover change has been dramatic over the last few centuries and is frequently invoked as a major cause of wildlife population declines. Baseline data currently used to assess population trends, however, began well after major changes to the landscape. In the United States and Canada, breeding bird population trends are assessed by the North American Breeding Bird Survey, which began in the 1960s. Estimates of distribution and abundance prior to major habitat alteration would add historical perspective to contemporary trends and allow for historically based conservation targets. We used a hindcasting framework to estimate change in distribution and abundance of 7 bird species in the Willamette Valley, Oregon (United States). After reconciling classification schemes of current and 1850s reconstructed land cover, we used multiscale species distribution models and hierarchical distance sampling models to predict spatially explicit densities in the modern and historical landscapes. We estimated that since the 1850s, White-breasted Nuthatch (Sitta carolinensis) and Western Meadowlark (Sturnella neglecta) populations, 2 species sensitive to fragmentation of oak woodlands and grasslands, declined by 93% and 97%, respectively. Five other species we estimated nearly stable or increasing populations, despite steep regional declines since the 1960s. Based on these estimates, we developed historically based conservation targets for amount of habitat, population, and density for each species. Hindcasted reconstructions provide historical perspective for assessing contemporary trends and allow for historically based conservation targets that can inform current management.
在过去的几个世纪里，全球范围内的人为土地覆盖变化非常剧烈，经常被认为是野生动物数量减少的主要原因。然而，目前用于评估种群趋势的基线数据是在景观发生重大变化之后开始的。在美国和加拿大，通过北美繁殖鸟类调查来评估繁殖鸟类的种群趋势，该调查始于 20 世纪 60 年代。在主要栖息地发生变化之前，对分布和数量的估计将为当代趋势提供历史视角，并允许基于历史的保护目标。我们使用回溯框架来估计俄勒冈州威拉米特谷（美国）7 种鸟类的分布和数量变化。在协调了当前和 19 世纪 50 年代重建土地覆盖的分类方案之后，我们使用多尺度物种分布模型和分层距离抽样模型来预测现代和历史景观中的空间明确密度。我们估计，自 19 世纪 50 年代以来，白胸五子雀（Sitta carolinensis）和西部草地鹨（Sturnella neglecta）的数量分别减少了 93%和 97%，这两种物种对橡木林地和草原的破碎化很敏感。另外 5 种物种我们估计其种群数量几乎稳定或增加，尽管自 20 世纪 60 年代以来该地区的数量急剧下降。根据这些估计，我们为每个物种制定了基于历史的栖息地数量、种群数量和密度的保护目标。回溯重建为评估当代趋势提供了历史视角，并允许制定基于历史的保护目标，为当前的管理提供信息。
