Abstract:

Aims: Generally, mountainous areas in high altitudes have harsh climate conditions and a lack of resources. It is important to understand the formation and maintenance mechanisms of biodiversity patterns in alpine ecosystems by exploring how closely related species that are sympatric use limited resources to achieve stable coexistence. Galliformes are typical ground-dwelling species with weak flight and dispersal abilities, and face higher interspecific competition pressure due to relatively narrower niches. Our study aims to compare the temporal and spatial niches of sympatric Galliformes species, and to provide a new case study for understanding the coexistence mechanism of sympatric species in alpine ecosystems.
Methods: From April to September 2020, field surveys were conducted in an alpine ecosystem at an altitude of 3,300-4,200 m in the Wolong National Nature Reserve, Sichuan Province. We used a transect survey design to investigate the microhabitats of the Chinese monal (Lophophorus lhuysii), chestnut-throated partridge (Tetraophasis obscurus), and snow partridge (Lerwa lerwa) who dominate the alpine Galliformes community and monitored their activity by infrared camera traps. Their ecological niches were compared along the two dimensions of microhabitat utilization and daily activity rhythm by using the kernel density estimation method.
Results: The results indicated that there were significant differences in both microhabitat utilization and daily activity rhythm between the snow partridge and the other two species. The Chinese monal and chestnut-throated partridge have similar preference in microhabitat utilization; the morning activity peaks of Chinese monal were later than those of chestnut-throated partridge, while its evening activity peaks were earlier than those of chestnut-throated partridge, demonstrating significant interspecific differences in daily activity rhythm; however, their overall niche integrating the two dimensions still highly overlaps without significant differentiation.
Conclusion: Our study reveals that niche differentiation among sympatric alpine Galliformes species is reflected along multiple ecological dimensions, and differentiation patterns vary between different species. The significant differentiation of the snow partridge in spatial and temporal niches is likely makes it less competitive with sympatric species, which is beneficial to its stable coexistence within the community. The overall niches of the Chinese monal and chestnut-throated partridge overlaps greatly. Therefore, it is recommended that further studies be conducted on their feeding habits and to explore the potential interspecific differentiation in trophic niches.

Key words: sympatric species, niche differentiation, kernel density estimation, microhabitat, daily activity rhythm