Which acoustic features of distressed calls do crows avoid? Revealing from Call Mimicry

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06367
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 42010:Animal production science-related
• Research Institution: Utsunomiya University
• Principal Investigator: Tsukahara Naoki 宇都宮大学, バイオサイエンス教育研究センター, 特任助教 (00712704)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: カラス / ディストレスコール / 鳴き声 / 鳴き真似 / playback実験 / 種差 / 地域差 / 季節性

Outline of Final Research Achievements

In this study, we prepared crow's vocalizations that induce avoidance behavior in crows and sounds with processed acoustic features, and compared the sounds that induced avoidance behavior with other sounds to identify acoustic features important for inducing avoidance behavior.
As a result, it was found that if the basic structure of the frequency components is maintained, avoidance behavior can be induced even if features such as the pitch and length of the sound are varied. In addition, it was found that when different sounds were played in succession, the avoidance behavior could be maintained even if a sound with a small change in acoustic characteristics was played first, and then a sound with a large change in acoustic characteristics was played after inducing the avoidance behavior. Furthermore, it was found that habituation occurred quickly to sounds with large changes in acoustic characteristics.

Free Research Field

動物行動学

Academic Significance and Societal Importance of the Research Achievements

本研究により、カラスの音声コミュニケーションの理解が進んだ。特に警戒時の行動の特徴やその種差、個体差、季節性などが明らかとなり、鳥類学の進展に寄与する学術的意義の高い知見が得られた。
また、本研究の成果は、カラスによる農作物被害や市街地の糞害など、様々な被害現場での活用が期待され、社会的意義も高い。実際にカラスによるごみ荒らし被害現場において実証試験を行ったところ、ある忌避音声を再生し、2箇月程度で慣れを確認した後、同じ忌避音声の周波数を変化させた音声を再生したところ、慣れの解消を確認し、また2箇月程度忌避効果を確認し、被害を軽減できた。