Wildlife crossing structures (WCSs) enhance connectivity between habitats of wild animals fragmented by fenced motorways, but factors affecting their use by targeted species remain understudied, particularly in areas recently recolonized by large carnivores. We investigated the use of WCS—6 overpasses (width 30-45m), 5 large underpasses (width 33–114 m) and 4 small underpasses (width 15–19 m)—located along the A4 motorway in the Lower Silesian Forest (western Poland), a large forest tract recently recolonised by wolves (Canis lupus). Identifying and counting tracks of mammals left on sand-beds as well as individuals recorded by camera traps were used to determine species diversity, number and activity patterns of mammals on WCS, and to reveal seasonal and temporal changes of WCS use over 3 years of study (2010–2013). WCSs were mostly used by wild species (51.5%), followed by humans (34.8%), livestock and pets (13.7%). Among wild species, ungulates were the most common (77.4% of crossings), while lagomorphs and carnivores were recorded less often (15% and 7.6% of crossings, respectively). The number of species and crossings of wild mammals, especially wild ungulates and wolves, was substantially higher on overpasses (mean effective number of species (Hill numbers): ⁰D = 7.8, ¹D = 4.1 and ²D = 3.3) than on underpasses (⁰D = 6.3, ¹D = 2.9 and ²D = 2.3) and was not affected by distance between WCS and human settlements or WCS width. There was a higher diversity of wild species and more crossings under large extended bridges than on smaller underpasses. The number of species and number of crossings of wild mammals, domestic animals and people increased from 2010 to 2013. There was a significant difference in activity patterns, with almost all wild species being nocturnal, in contrast to people and dogs. There was no relationship between crossing time and rates of wild carnivores and potential prey. We conclude that overpasses, even with steep entrance slopes (25–26.5%) or integrated with moderately used gravel roads, maintain movement of wild terrestrial mammals much better than underpasses, and the presence of wolves does not hamper the movement of other wild species. As there are significant temporal changes in use of WCS by mammals, we recommend monitoring WCS in all seasons for at least 3 years as a minimum standard for the post-investment assessment of WCS utilization by animals.

中文翻译：

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在最近被狼重新定殖的区域内，沿新高速公路对野生动物穿越结构的哺乳动物利用

野生动物穿越结构（WCS）增强了被围栏高速公路打碎的野生动物的栖息地之间的连通性，但是影响目标物种使用它们的因素仍然未被研究，特别是在最近被大型食肉动物重新定殖的地区。我们调查了WCS的使用情况，它们位于西里西亚下森林（西部）的A4高速公路上，有6个天桥（宽度30-45m），5个大地下通道（宽度33-114 m）和4个小地下通道（宽度15-19m）。波兰），最近被狼（Canis lupus）重新定殖的大型森林地带）。识别和计数留在沙床上的哺乳动物以及通过相机陷阱记录的个体的轨迹，用于确定WCS上哺乳动物的物种多样性，数量和活动模式，并揭示三年研究中WCS使用的季节性和时间变化（2010年至2013年）。WCS主要用于野生物种（51.5％），其次是人类（34.8％），牲畜和宠物（13.7％）。在野生物种中，有蹄类动物是最常见的（占杂交的77.4％），而记录下来的有鳄鱼和食肉动物的频率较低（分别占杂交的15％和7.6％）。种和野生哺乳动物，尤其是有蹄类动物野生和狼，的横跨的数目是在立交桥（平均有效数种（山数）显着更高：⁰ d = 7.8，¹ d= 4.1和² d = 3.3）大于上地下通道（⁰ d = 6.3，¹ d = 2.9和² d= 2.3），并且不受WCS与人类住区之间的距离或WCS宽度的影响。与较小的地下通道相比，大型延伸桥下野生物种的多样性更高，并且穿越的次数更多。从2010年到2013年，野生哺乳动物，家畜和人的物种数量和穿越次数增加。活动模式存在显着差异，与人和狗相比，几乎所有野生物种都是夜行性的。穿越时间和野生食肉动物的数量以及潜在猎物之间没有关系。我们得出的结论是，即使有陡峭的入口坡度（25–26.5％）或与适度使用的碎石路相结合的立交桥，野生陆生哺乳动物的活动仍比立交桥更好，并且狼群的存在并不妨碍其他野生物种的活动。