Effects of invasive alien plants and habitat structure on bird assemblages in a unique lowland forest in eastern Nepal

Abstract Invasive alien species play a major role in biodiversity decline. We studied the impacts of invasive alien plant species (IAPS) on bird assemblages and their habitats in Jalthal Forest, a biogeographically unique lowland remnant forest in eastern Nepal. We surveyed birds by point counts and quantified environmental variables at 89 sites. Observations of 1,373 individuals of 86 species showed that species richness was the highest in wooded grasslands and floodplains and lowest in sal forests invaded by IAPS, whereas abundance was highest in IAPS-invaded forests. Abundance and richness decreased with increasing cover of IAPS, shrub cover and distance to water. The abundance and richness of every feeding guild except omnivores were negatively correlated with IAPS cover. Our results increase our understanding of the impacts of IAPS on birds and clearly indicate the need of controlling IAPS in Jalthal Forest, and thus, are valuable for forest management and biodiversity conservation.