Impacts of livestock grazing on blue-eared pheasants (Crossoptilon auritum) survival in subalpine forests of Southwest China 散放家畜对中国西南山地亚高山森林雉类蓝马鸡的影响

Abstract

The degradation and fragmentation of natural habitats, driven largely by anthropogenic activities such as grazing, represent growing concerns in environmental conservation. We examined the impact of grazing activities on the survival of the blue-eared pheasant Crossoptilon auritum, a ground-nesting bird endemic to subalpine forests. Using camera-trapping and artificial nest experiments, we compared two sites in Sichuan, China: Wanglang (high grazing intensity) and Jiuzhaigou (no grazing) national nature reserves. The study, conducted from 2017 to 2021, evaluated habitat suitability changes for these pheasants and examined the impact of grazing on nesting success by conducting a nest predation experiment. The results of our study showed that (1) since the significant increase of free-ranging livestock post-2014, the area of most suitable and moderately suitable habitats for blue-eared pheasants in Wanglang decreased by 14.28% (net loss 15.12 km²); (2) predominant natural predators of the pheasant, such as yellow-throated martens (Martes flavigula) and leopard cats (Prionailurus bengalensis), were mostly observed to be spatially distant from livestock; (3) the pheasant's nesting failure rate was 2.18 times higher in Wanglang than in Jiuzhaigou; (4) high-intensity livestock disturbance correlated with decreased food resources for pheasants, yet resulted in an increased abundance of Coleopteran insects. These results illustrate a complex dynamic: Although forest pheasants, such as the blue-eared pheasant, may initially benefit from the presence of livestock through increased predator refuge and access to specific food resources, they ultimately face greater risks. These include a significant increase in nest failure rates and remarkable habitat loss and degradation. In light of these results, we advocate for strict control and management of grazing activities inside reserves. Additionally, we recommend the implementation of a systematic monitoring program that focuses on the population dynamics and habitat use of endangered pheasants in Southwest China.