Impacts of the Non-environmental Factors on Covariance Between Avian and Mammalian Species Richness

There are significant correlations between different taxonomic groups with respect to species richness. However, different studies yield different correlation coefficients between taxonomic groups. In this paper we analysed the impacts of some non-environmental potential factors, such as area effects, taxonomic groups, spatial scale, species distribution, avian residents and travelers on species richness covariance among taxonomic groups. Our results showed that significant covariance only occurred between the taxonomic groups with similar origins and ecologies. There were no area effects in our data set. Spatial scale affected covariance among taxonomic groups, although similar trends only occurred with similar scales. Species with different distribution patterns showed significantly different covariance. There were higher correlations in Oriental species richness than in Paleoartic species richness or between both species. The species richness of avian breeds had very significant covariance with mammals in terms of species richness rather than with other avian ecological types. Therefore, the ecological types and origins of taxonomic groups may have impacts on the covariance of species richness among these taxonomic groups.