2018 Volume 14 Pages A33-A44
The avian community in the urban environment changes over time. In order to describe characteristics of the avian community in residential areas in the early 21st century, we quantitatively analyzed database records of a locality within “the Verandah Birdwatching,” a citizen-science survey in which people monitor the abundance of birds around their houses. Using the dataset of the Kanto Region, which had enough data for our analysis, we revealed the following community and temporal characteristics: 1) major species with a large number of recorded sites, 2) species with a high frequency of recordation, 3) differences in the avian communities present during breeding and wintering seasons, 4) annual variations of species richness, and 5) alien species recorded in residential areas. In any season, Tree Sparrows and Brown-eared Bulbuls were the most frequently recorded species. The majority of species that were recorded frequently were those that tend to use or depend on man-made habitat, such as artificial structures, street trees and landscaping. In the case of Japanese White-eye, Oriental Greenfinch, White Wagtail, and Japanese Bush Warbler, the frequency of recordation and/or number of recorded sites showed high seasonal variation. Changes in the number of individuals, changes in behavior, presence or absence of attractants like feeders, and ease of recognition by observers were considered to be reasons for the large seasonal fluctuation of rank for some birds. Long-term study indicated that the species richness observed at each site was stable during the breeding season, whereas that of the wintering season was variable. In order to establish a firm basis for a long-term monitoring system, it is important to increase the number of survey sites and to maintain observation activity in the future. For the Verandah Birdwatchers to take the role of monitoring surveyors, it is necessary for the organizers to provide feedback to the participants regularly, such as by publishing the survey results.
