Scaring Effect of Face of Mannequin on the Rufous Turtle Dove

27 Mar Scaring Effect of Face of Mannequin on the Rufous Turtle Dove

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Abstract

キジバトの視覚刺激(マネキン人形)に対する反応の個体変異,ならびに1個体の場合と複数個体を同時に使った場合の刺激に対する反応の違いを,大型網室を使って実験的に調べた.実験には3羽のキジバトを用い,また2か所の餌場に,顔を露出したマネキンと全身を布で覆ったマネキンをランダムに配置し,それぞれの餌場でのキジバトの採食行動を観察した. 1) 対照実験(餌だけを2か所の餌場に与えた実験)から,キジバトはどちらかの餌場を特に好むという傾向は認められなかった. 2) マネキンに対する反応には顕著な個体変異がみられた.個体Aは,明らかに顔を露出したマネキンを忌避し,個体Bはマネキンそのものを忌避し実験期間中(11日間)1度も餌場に現れなかった.個体Cは,最初の6日間はマネキンを忌避していたが,その後餌場を訪れるようになった.しかし,この個体は両方の餌場で採食し,マネキンの顔が露出しているかどうかを区別しなかった. 3) 個Bと個体Cを用いた実験では,前者が1度だけ餌場に現れたのを除いて,個体Cだけが餌場で採食していた. 4) 3個体を同時に使った実験では,個体Aは両方の餌場で採食するようになり,個体Bも他の2個体に比べれば短かかったが,両方の餌場に現れるようになった.また,この実験では,餌場周辺での個体間の干渉がみられた. 5) 複数個体を使った実験の結果には,見かけ上,刺激に対する反応の弱い個体の行動が反映されやすい. 6) 個体ごとの実験と複数個体を使った実験における個体の採食行動の変化について,実験の経過に伴う慣れ,個体間の干渉,群れとしての行動の質的変化などの点から考察を行った.

English Abstract

Experiments were conducted in order to demonstrate that 1) the individual variation of responses to visual stimulus by Rufous Turtle Doves Streptopelia orientalis and 2) the differences between responses to stimulus presented to only one dove and two or more. Three doves were used in the experiment in which two mannequins were placed by the two feeding sites, respectively, in a large cage (58×20 m, height 12 m). The mannequins, one was covered the whole body with red cloth and another was the same as the former but exposed her face, were changed the setting places randomly. The responses to the stimulus were measured by foraging behavior of doves, e.g. the amount of food that bird consumed, and the time from feeding to the onset of foraging.
1) The control experiment in which no mannequins were installed by the feeding sites shows that birds had no tendency to prefer to one feeding site.
2) The responses to the stimulus differed among individuals. Dove A clearly avoided the mannequin that exposed the face, and Dove B avoided two mannequins irrespective of the face exposed or covered and did not come to feeding sites for 11 experimental days. Dove C also avoided the two mannequins for the first 6 days, and thereafter visited the feeding sites without any particular aversion to one type of mannequin.
3) The experiment involved Doves B and C showed that the latter appeared to the feeder exclusively, while the former visited there once.
4) In the experiment involved all three doves, Dove A became to visit two feeding sites and Dove B also appeared to two feeding sites. Interference by the feeding site was recorded between individuals in which Dove C was always domi nt to other doves.
5) The result of the experiment involved two or more doves appear to be strongly reflected the behavior of the individuals that responded to the stimulus rather weakly.
6) I discussed the changes of the foraging behavior of doves, when they were used in single or plural individuals in experiment, from the view point of acclimation to the stimulus with the progress of experiment, individual interference, and the change of behavior of doves when they formed flocks.