Relationship between the breeding distribution of forest birds and annual mean temperature based on two national surveys in Japan

Abstract

Using data from two national breeding-bird surveys, the Japan Breeding Bird Atlas and Monitoring Site 1000, we determined the average temperature of forest bird habitats during the breeding season. The mean temperatures of the distribution areas of various bird species (species temperature index: STI) calculated from both surveys were a good match and seemed reliable. However, the values calculated from the Monitoring Site 1000 tended to be slightly higher than those calculated from the Japan Breeding Bird Atlas, which may be due to the smaller number of survey sites in Hokkaido in Monitoring Site 1000. Therefore, STI from the Japan Breeding Bird Atlas seems more reliable as an index. We identified species groups suitable for monitoring the effects of climate change in the future. One is the species group whose distribution area is biased toward warmer regions, and the other is toward colder regions. The former includes Varied Tit Poecile varius, Brown-eared Bulbul Hypsipetes amaurotis, and Japanese White-eye Zosterops japonicus, and the latter includes Japanese Leaf Warbler Phylloscopus xanthodryas and Eurasian Bullfinch Pyrrhula pyrrhula.