Liu Wei, Wu Yongjie, DuBay Shane G, Zhao Chenhao, Wang Bin, Ran Jianghong
Key Laboratory of Bio-resources and Eco-environment of Ministry of Education, College of Life Sciences Sichuan University Chengdu China.
College of Life Sciences Huaibei Normal University Huaibei China.
Ecol Evol. 2019 Jan 28;9(4):2096-2105. doi: 10.1002/ece3.4904. eCollection 2019 Feb.
Variation in grassland vegetation structure influences the habitat selection of insectivorous birds. This variation presents a trade-off for insectivorous predators: Arthropod abundance increases with vegetation height and heterogeneity, but access to arthropod prey items decreases. In contrast, grazing by large herbivores reduces and homogenizes vegetation, decreasing total arthropod abundance and diversity. However, the presence of livestock dung may help counteract the overall reduction in invertebrates by increasing arthropods associated with dung. It is unclear, however, how the presence of arthropod prey in dung contributes to overall habitat selection for insectivorous birds or how dung-associated arthropods affect trade-offs between vegetation structure, arthropod abundance, and access to prey. To explore these relationships, we studied habitat selection of the Black-necked Crane (), a large omnivorous bird that breeds on the Qinghai-Tibet Plateau. We assessed the relationships between habitat selection of cranes and vegetation structure, arthropod abundance, and the presence of yak dung. We found that Black-necked Cranes disproportionately foraged in grassland patches with short sward height, low sward height heterogeneity, and high numbers of dry yak dung, despite these habitats having lower total arthropod abundance. Although total arthropod abundance is lower, these habitats are supplemented with dry yak dung, which are associated with coleopteran larvae, making dung pats an indicator of food resources for breeding Black-necked Cranes. Coleopteran adults and larvae in yak dung appear to be an important factor influencing the habitat selection of Black-necked Cranes and should be considered when assessing grassland foraging trade-offs of insectivorous birds. This research provides new insights into the role of livestock dung in defining foraging habitats and resources for insectivorous predators.
草原植被结构的变化会影响食虫鸟类的栖息地选择。这种变化对食虫性捕食者而言是一种权衡：节肢动物的数量会随着植被高度和异质性的增加而增多，但获取节肢动物猎物的机会却会减少。相比之下，大型食草动物的啃食会降低植被高度并使其同质化，从而减少节肢动物的总数量和多样性。然而，牲畜粪便的存在可能有助于抵消无脊椎动物数量的总体减少，因为它会增加与粪便相关的节肢动物数量。然而，尚不清楚粪便中的节肢动物猎物对食虫鸟类的整体栖息地选择有何贡献，也不清楚与粪便相关的节肢动物如何影响植被结构、节肢动物数量和猎物获取之间的权衡。为了探究这些关系，我们研究了黑颈鹤（一种在青藏高原繁殖的大型杂食性鸟类）的栖息地选择。我们评估了鹤类的栖息地选择与植被结构、节肢动物数量以及牦牛粪便存在之间的关系。我们发现，黑颈鹤在草地斑块中觅食的比例过高，这些草地斑块的草皮高度较低、草皮高度异质性较低且干牦牛粪便数量较多，尽管这些栖息地的节肢动物总数量较低。尽管节肢动物的总数量较低，但这些栖息地有干牦牛粪便作为补充，而干牦牛粪便与鞘翅目幼虫有关，这使得粪堆成为繁殖期黑颈鹤食物资源的一个指标。牦牛粪便中的鞘翅目成虫和幼虫似乎是影响黑颈鹤栖息地选择的一个重要因素，在评估食虫鸟类的草地觅食权衡时应予以考虑。这项研究为牲畜粪便在确定食虫性捕食者的觅食栖息地和资源方面的作用提供了新的见解。
