Department of Ecology, Environment, and Evolution, La Trobe University, Melbourne, Victoria, Australia.
Elanus Consulting, St Andrews, Victoria, Australia.
Ecol Appl. 2022 Jul;32(5):e2587. doi: 10.1002/eap.2587. Epub 2022 Apr 28.
Livestock grazing is an important management tool for biodiversity conservation in many native grasslands across the globe. Understanding how different grazing species interact with their environment is integral to achieving conservation goals. In the semiarid grasslands of Australia, grazing by sheep or cattle is used to manipulate vegetation structure to suit the habitat needs of a globally unique, critically endangered grassland bird, the plains-wanderer Pedionomus torquatus. However, there has been no investigation of whether sheep and cattle differ in their effects on plains-wanderer habitat and, therefore, it is unknown if these grazers are substitutable as a management tool. Using a grazing experiment in native grasslands over 3 years, we determined the effects of grazer type (sheep, cattle) on occurrence and vocal activity of plains-wanderer, vegetation structure and composition, and food availability. We also examined grazer effects on encounter rates of other grassland birds. Plains-wanderer breeding activity was inferred from vocalization rates captured by bioacoustic recorders. Spotlighting was used to measure encounter rates of other grassland birds. We found that different grazers altered the structure of the habitat. Grasslands grazed by cattle were typically more open, less variable, and lacked patches of dense vegetation relative to those grazed by sheep. Grazer type did not influence the likelihood of plains-wanderer occurrence, but it did interact with year of survey to affect breeding activity. The number of days with one or more calls significantly increased at sheep grazed sites in year-3, which coincided with enduring drought conditions. Similarly, grazer effects on encounter rate of all birds, bird species richness, and Australasian pipit Anthus novaeseelandiae were different between years. Dense vegetation specialists (such as stubble quail Coturnix pectoralis) were positively associated with grasslands grazed by sheep. As a habitat management tool, sheep or cattle grazing are useful when the goal is to support an open grassland structure for the plains-wanderer. However, their substitutability is likely to be dependent upon climate. We caution that a loss of dense vegetation in grasslands grazed by cattle during drought could limit the availability of optimal habitat for the plains-wanderer and habitat for other grassland birds.
家畜放牧是全球许多原生草原地区生物多样性保护的重要管理工具。了解不同放牧物种如何与环境相互作用对于实现保护目标至关重要。在澳大利亚半干旱草原地区，绵羊或牛的放牧被用来操纵植被结构，以适应一种全球独特的、极度濒危的草原鸟类——平原 wanderer Pedionomus torquatus 的栖息地需求。然而，目前还没有研究绵羊和牛在对平原 wanderer 栖息地的影响方面是否存在差异，因此，尚不清楚这些放牧者是否可以作为一种管理工具相互替代。我们通过在原生草原上进行了为期 3 年的放牧实验，确定了放牧物种（绵羊、牛）对平原 wanderer 的出现和发声活动、植被结构和组成以及食物可获得性的影响。我们还研究了放牧者对其他草原鸟类的遭遇率的影响。平原 wanderer 的繁殖活动是通过生物声学记录器捕捉到的发声率来推断的。利用聚光灯来测量其他草原鸟类的遭遇率。我们发现，不同的放牧者改变了栖息地的结构。与被绵羊放牧的草原相比，被牛放牧的草原通常更开阔、更稳定，且缺乏茂密植被的斑块。放牧物种类型不会影响平原 wanderer 的出现概率，但它会与调查年份相互作用，从而影响繁殖活动。在绵羊放牧的地点，有一个或多个叫声的天数在第 3 年显著增加，这与持续干旱的情况相吻合。同样，放牧对所有鸟类、鸟类物种丰富度和澳大拉西亚 pipit Anthus novaeseelandiae 的遭遇率的影响在不同年份也有所不同。密集植被的特有种（如 stubble quail Coturnix pectoralis）与被绵羊放牧的草原呈正相关。作为一种栖息地管理工具，绵羊或牛的放牧在支持平原 wanderer 的开阔草原结构时是有用的。然而，它们的可替代性可能取决于气候。我们警告说，在干旱期间，被牛放牧的草原上密集植被的丧失可能会限制平原 wanderer 和其他草原鸟类的最佳栖息地的可获得性。
