Research Station Petite Camargue Alsacienne, Saint Louis, France.
Department of Environmental Sciences, Universität Basel, Basel, Switzerland.
PeerJ. 2024 Jul 19;12:e17777. doi: 10.7717/peerj.17777. eCollection 2024.
A challenge in grassland conservation is to maintain both the openness and the heterogeneity of the habitat to support the diversity of their animal communities, including birds-a taxon that is known to be sensitive to disturbance. An increasingly used management tool in European grassland conservation, especially in rewilding projects, is grazing by large herbivores such as horses and cattle. These grazers are believed to create and maintain patchy landscapes that promote diversity and richness of other species, but their influence on birds is often debated by conservationists, who raise concerns about the impact of disturbance by the grazers.
Our aim was to examine the relationship between the abundance and species richness of birds across four foraging guilds and the area utilization patterns of Highland cattle and Konik horses in an alluvial grassland in France. We also aimed to examine the influence of land cover and season on the spatial distribution, including abundance and species richness, of different bird guilds present in the grazed area.
We used GPS-collars on all grazers and recorded their positions on an hourly basis over a study period of 1.5 years, assessing patterns of area usage. We counted birds weekly along three transects to describe their distribution within the grazed area and carried out land-cover surveys to describe the habitat. To assess how species richness and abundance of birds of different guilds were related to grazer density, season, and habitat characteristics, we used GAMM models in a spatially explicit framework. We also compared bird numbers at our main study site with a nearby non-grazed control area.
The number of birds in the grazed area was about twice the number in the non-grazed control area. Within the grazed area, the abundance of open-area foraging birds increased with increasing grazer density. The number of woodland-foraging birds was also positively correlated with grazer density but less so than open-area foraging birds. The number of individuals in the aerial and wetland bird guilds was not correlated with the density of grazers. Most bird species and individuals were observed on open landscapes scattered with woody patches and waterbodies, and on areas with moderate grazer density.
Low-intensity grazing represents a potentially important management tool in creating heterogeneity in alluvial grasslands, thereby promoting suitable habitat for a diverse assemblage of bird species.
草原保护面临的一个挑战是保持栖息地的开放性和异质性，以支持其动物群落的多样性，包括鸟类——已知对干扰敏感的分类群。在欧洲草原保护中，特别是在重新引入野生动物项目中，越来越多使用的管理工具是大型食草动物（如马和牛）的放牧。这些食草动物被认为创造和维持了促进其他物种多样性和丰富度的斑块状景观，但它们对鸟类的影响经常受到保护主义者的争论，他们对食草动物干扰的影响表示担忧。
我们的目的是研究法国冲积草原中，四种觅食鸟类的丰富度和物种丰富度与高地牛和欧洲野牛的面积利用模式之间的关系。我们还旨在研究土地覆盖和季节对不同鸟类觅食群体在放牧区的空间分布（包括丰富度和物种丰富度）的影响。
我们在所有食草动物上使用 GPS 项圈，并在 1.5 年的研究期间每小时记录它们的位置，评估面积利用模式。我们每周在三条测线上对鸟类进行计数，以描述它们在放牧区的分布，并进行土地覆盖调查以描述栖息地。为了评估不同觅食鸟类的物种丰富度和丰度与食草动物密度、季节和栖息地特征的关系，我们在空间显式框架中使用 GAMM 模型。我们还将主要研究地点的鸟类数量与附近未放牧的对照区进行了比较。
放牧区的鸟类数量大约是未放牧对照区的两倍。在放牧区，开阔地觅食鸟类的数量随着食草动物密度的增加而增加。林地觅食鸟类的数量也与食草动物密度呈正相关，但不如开阔地觅食鸟类明显。水鸟和湿地鸟类的个体数量与食草动物密度无关。大多数鸟类物种和个体在散布着树木斑块和水体的开阔景观以及中等食草动物密度的区域中被观察到。
低强度放牧是在冲积草原中创造异质性的一种潜在重要管理工具，从而促进了各种鸟类物种的适宜栖息地。
