- 著者
-
西田 宗太郎
辻野 亮
- 出版者
- 奈良教育大学自然環境教育センター
- 雑誌
- 奈良教育大学自然環境教育センター紀要 = Bulletin of Center for Natural Environment Education, Nara University of Education (ISSN:21887187)
- 巻号頁・発行日
- no.17, pp.59-67, 2016-03
本研究では、カラス類によるゴミの食い荒らしの現状とゴミ回収の時間帯でのゴミ回収場所周辺のカラス類の出現数がどのような要因によって変化するかを明らかにするために、奈良市において燃やせるゴミ(生ごみを含む) の回収曜日が異なる2つの市街地において食い荒らしの生起頻度調査とカラス類出現数のスポットセンサスを行い、カラス類の出現数とゴミ回収区分、集積様式、調査サイトの相関関係を解析した。10月~12月の非繁殖期の燃やせるゴミの日に400分間、燃やせないゴミの日に400分間の観察によって、燃やせるゴミの日にのべ82羽、燃やせないゴミの日にのべ92羽のカラス類を記録した。また、2015年12月の非繁殖期の燃やせるゴミの日に200か所、燃やせないゴミの日に200か所のゴミ回収場所を観察した結果、燃やせるゴミの日に2か所、燃やせないゴミの日に3か所の食い荒らしを記録した。カラス類の出現数とゴミ回収区分、集積様式、調査サイトについて一般化線形混合モデルによって解析したところ、カラス類の出現数は燃やせないゴミの日に多くなることがわかったが、燃やせるゴミの日との差は小さかった。カラス類対策がある程度された現状では、ゴミ回収の時間帯にゴミ回収場所周辺でカラス類はあまり出現せず、カラス類はゴミを主要な餌資源とできない可能性が示唆された。The aims of this study are to clarify the present status of garbage scavenging by crows, and the relationship between crow occurrences and garbage collection in the non-breeding season. In the current study, the garbage collection sites, scavenged by crows, were counted and the spot censuses were conducted during garbage collecting time at two sites of urban area in Nara city. The relationships between the number of crow occurrence and either types of garbage (burnable/non-burnable garbage), type of protection at garbage collection site (no guard, by a net, and by a temporary box), or study sites. In December 2015, a non-breeding season, 2015, Two out of 200 sites were scavenged by crows on the day for collecting burnable garbage, three out of 200 sites were scavenged by crows on the day for collecting non-burnable garbage. FromOctober to December 2015 (non-breeding season), 82 corws were recorded in the total of 400 min. of census effort on the burnable garbage day and 92 crows were counted during a total of 400 min. of census effort on the non-burnable garbage day. The generalized liner mixed model analysis showed the number of crow occurrence increased on the non-burnable garbage day. However there was less difference in the number of crow occurrence between the non-burnable garbage day and the burnable garbage day. Since crow-repellent measures are effective these days, the number of crow occurrence around garbage collection sites, and the number of crow-scavenged case during the census effort were small. These suggest that the crow does notscavenge garbage as a main food resource.