Changes in the Number of Naturalized Rose-ringed Parakeet Psittacula krameri at the Roosting Sites in the Metropolitan Area of Tokyo and Kanagawa, Japan

Abstract

The Rose-ringed Parakeet Psittacula krameri has expanded its distribution worldwide. Wild populations have been observed in the Japanese Archipelago since the late 1960s, and there are concerns about their potential impacts on ecosystems and conflicts with humans. However, their behavior and habits in urban environments are still not well understood. We counted the number of individuals at four known roosting sites from July 2015 to January 2016. The numbers fluctuated greatly at all roosting sites. Human activities and seasonal changes in the environment likely caused these changes. The roosting site formed on Tilia maximowicziana was abandoned following leaf fall, whereas the use of Ginkgo biloba was continued after leaf fall. The population density increased as the roosting number of individuals increased because the physical size of the roost remained unchanged, which may result in problems with noise and bird feces to humans.