Overlap and selection of dust-bathing sites among three sympatric montane galliform species

摘要

Niche theory predicts that, to avoid interspecific competitive exclusion, ecologically similar bird species in sympatry should reduce habitat use overlap, especially when shared resources are limiting in an environment. Dust-bathing sites represent a distinctive behavior-specific habitat, differing from other habitats as they are used for short durations and infrequently. However, we have little understanding of selection, potential interspecific overlap, and partitioning of dust-bathing sites among sympatric species. In this study, we examined overlap and selection of dust-bathing sites of 3 sympatric montane galliform species on the Qinghai-Tibet Plateau: Blood Pheasant ( Ithaginis cruentus ), Szechenyi's Partridge ( Tetraophasis szechenyii ), and White Eared-Pheasant ( Crossoptilon crossoptilon ). We identified dust-bathing scrapes and measured habitat characteristics of dust-bathing sites along 10 transects established in Gexigou National Nature Reserve, Sichuan Province, China, from April to August in 2015. In total, we identified 105 dust-bathing scrapes and established 58 dust-bathing site quadrats. More than one-third of dust-bathing scrapes and ～20% of dust-bathing sites were used by multiple species. The 3 species showed no significant differences in the dimensions or soil particle size distributions of their dust-bathing scrapes, nor did we find that habitat features of dust-bathing sites differed significantly among the 3 species (all pairwise overlap indices 0.6). All 3 species preferred surrounding fir forests with dense tree and shrub strata, good concealment that could provide sufficient protection from predators and precipitation, and sparse grass cover with suitable substrates containing finer soil particles for better dust-bathing. Our results suggest that the 3 sympatric galliform species had similar habitat requirements that led to overlap in selection for dust-bathing sites. We recommend further monitoring of temporal use of dust-bathing sites by the 3 galliform species to test potential temporal partitioning mechanisms that may minimize competition between heterospecific and conspecific individuals.