Long-term trends in bird communities: estimation using national birding records and hierarchical Bayesian modelling

2022 Fiscal Year Final Research Report

• Project/Area Number: 17K15057
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Conservation of biological resources
• Research Institution: National Agriculture and Food Research Organization
• Principal Investigator: KATAYAMA Naoki 国立研究開発法人農業・食品産業技術総合研究機構, 農業環境研究部門, 主任研究員 (10631054)
• Project Period (FY): 2017-04-01 – 2023-03-31
• Keywords: 生物多様性保全 / 鳥類群集 / 個体数トレンド / 農業生態系 / 里山

Outline of Final Research Achievements

Several existing data including previous bird-survey data and field surveys were conducted to clarify the changing trends of Japanese terrestrial bird populations. (1) Analysis of existing data and field surveys in Ibaraki Prefecture (N-mixture model) suggested that the Greater Painted Snipe population has decreased by about 1/10 over the past 20 years and that one of the main reasons for this is the decrease in flooded fallow fields. (2) An analysis (TRIM) of Monitoring Site Project 1000 data showed that 47 common species have shown a declining trend over the 12 years 2009-2020. Of these, forested species showed a slight increase, while satoyama and open land species showed a decreasing trend. (3) The data compilation of the national birdwatching records has been progressed and data input has been completed for approximately 90% of the records. Further input and analysis will be carried out in the future.

Free Research Field

生物多様性保全

Academic Significance and Societal Importance of the Research Achievements

農林業などの土地利用の変化にともなう生物多様性の変化傾向（トレンド）を定量化することで、生物多様性の現状を理解すると同時に、必要な保全管理策について理解を深めることができる。本研究は人口減少による農林業の衰退が生じている日本において、タマシギや里山性鳥類の個体数が減少していることを示し、彼らの個体数増加には遷移初期生息地を維持するための人為的介入が必要であることを明らかにした。欧米と比較して日本の生物多様性トレンドの定量化はこれまでほとんどなされておらず、COP15の自然共生社会の実現に向けて、国際的にもデータの不足しがちなアジアの貴重な知見の一つとなった。