García-González Ricardo, Aldezabal Arantza, Laskurain Nere Amaia, Margalida Antoni, Novoa Claude
Instituto Pirenaico de Ecología (CSIC), Jaca, Spain.
Plant Biology and Ecology Department, Basque Country University, Bilbao, Spain.
PLoS One. 2016 Feb 10;11(2):e0148614. doi: 10.1371/journal.pone.0148614. eCollection 2016.
The Pyrenean rock ptarmigan (Lagopus muta pyrenaica) lives at one of the southernmost limits of the ptarmigan range. Their small population sizes and the impacts of global changes are limiting factors in the conservation of this threatened subspecies. An effective conservation policy requires precise basic knowledge of a species' food and habitat requirements, information that is practically non-existent for this Pyrenean population. Here, we describe the diet of a ptarmigan population in the Eastern Pyrenees, the environmental factors influencing its variability and the relationship between diet floristic composition and quality. Diet composition was determined by microhistological analysis of faeces and diet quality was estimated from free-urate faecal N content. Our results show that grouse diet is based mainly on arctic-alpine shrubs of the Ericaceae family, as well as dwarf willows (Salix spp.) and Dryas octopetala. The most frequently consumed plant species was Rhododendron ferrugineum, but its abundance in the diet was negatively related to the diet nitrogen content. Conversely, the abundance of Salix spp., grass leaves and arthropods increased the nitrogen content of the diet. Seasonality associated with snow-melting contributed the most to variability in the Pyrenean ptarmigan diet, differentiating winter from spring/summer diets. The latter was characterised by a high consumption of dwarf willows, flowers, arthropods and tender forb leaves. Geographic area and sex-age class influenced diet variability to a lesser extent. Current temperature increases in the Pyrenees due to global warming may reduce the persistence and surface area of snow-packs where preferred plants for rock ptarmigan usually grow, thus reducing food availability. The high consumption of Rh. ferrugineum characterised the diet of the Pyrenean population. Given the toxicity of this plant for most herbivores, its potential negative effect on Pyrenean ptarmigan populations should be evaluated.
比利牛斯岩雷鸟（Lagopus muta pyrenaica）生活在雷鸟分布范围最南端的区域之一。其种群数量稀少以及全球变化的影响是保护这一濒危亚种的限制因素。有效的保护政策需要精确掌握一个物种的食物和栖息地需求等基础知识，而对于比利牛斯地区的这一种群，此类信息几乎不存在。在此，我们描述了东比利牛斯地区一群岩雷鸟的饮食、影响其饮食变化的环境因素以及饮食植物组成与质量之间的关系。通过对粪便进行微观组织学分析来确定饮食组成，并根据粪便中游离尿酸氮含量估算饮食质量。我们的结果表明，松鸡的饮食主要以杜鹃花科的北极 - 高山灌木、矮柳（柳属植物）和八瓣仙女木为主。最常食用的植物物种是铁锈色杜鹃，但它在饮食中的丰度与饮食氮含量呈负相关。相反，柳属植物、草叶和节肢动物的丰度增加了饮食中的氮含量。与融雪相关的季节性因素对比利牛斯岩雷鸟的饮食变化影响最大，使冬季饮食与春季/夏季饮食有所不同。春季/夏季饮食的特点是大量食用矮柳、花朵、节肢动物和嫩草本植物叶子。地理区域和性别 - 年龄类别对饮食变化的影响较小。由于全球变暖，比利牛斯地区目前气温上升可能会减少岩雷鸟偏好的植物通常生长的积雪层的持久性和表面积，从而降低食物供应量。铁锈色杜鹃在比利牛斯种群的饮食中占很大比例。鉴于这种植物对大多数食草动物具有毒性，应评估其对比利牛斯岩雷鸟种群的潜在负面影响。
