Fixed eyespot display in a butterfly thwarts attacking birds| |
References
PDF (411 K)Animal Behaviour
Volume 77, Issue 6, June 2009, Pages 1415-1419
Ullasa Kodandaramaiah, Adrian Vallina and Christer Wiklunda
Volume 77, Issue 6, June 2009, Pages 1415-1419
Ullasa Kodandaramaiah, Adrian Vallina and Christer Wiklunda
Department of Zoology, Stockholm University, Sweden
Available online 10 April 2009.
眼紋出現在許多鱗翅目昆蟲中，被猜測具有適應上的價值。所提出的假說中其中一個功能是捕食者會被獵物身上大而醒目的眼紋驚嚇，接著避免攻擊這類獵物。近期實驗顯示，眼紋與恫嚇行為的結合可提升存活率。作者測試僅僅存在明顯的眼紋時、是否可以嚇退攻擊的鳥類，意即不斷地展示眼紋而不表現恫嚇行為。作者將孔雀蛺蝶 Junonia almana 的翅膀黏貼在一片卡紙上以模擬成一隻蝴蝶展翅的樣貌，同時將ㄧ隻麵包蟲黏在雙翅中央身體的位置。此實驗中以山雀 Parus major 作為捕食者，在”具有眼紋”與”塗去眼紋”兩種模式獵物中做出選擇。具有眼紋的獵物顯著地比塗去眼紋者較少受到攻擊，首次攻擊與第二次攻擊之間間隔的時間也比被塗去眼紋者更長。以上結果支持天然產生的蝴蝶眼紋可提升存活率，即便是在持續展示且靜止不動的的情形下。
Abstract
Eyespots have evolved in many lepidopteran insects, which suggests their adaptive value. One of their hypothesized functions is that predators are intimidated by prey with large and conspicuous eyespots and hence refrain from attacking them. Recent experiments have shown that a combination of eyespots and intimidating behaviour can increase survival. We tested whether the mere presence of conspicuous eyespots can thwart attacking birds, that is, when the eyespots are displayed constantly, without any intimidating behaviour. We used prey that consisted of wings of the peacock pansy butterfly, Junonia almana, glued onto a piece of cardboard so as to resemble a butterfly with its wings open. A mealworm was placed between the wings in place of the body. Great tits, Parus major, were used as the predator in the study and were offered a choice between two model prey, one with intact eyespots and one without. Prey with eyespots were attacked significantly fewer times than those without. The time between the first and second attack was longer when the prey without eyespots was attacked first. These results support the hypothesis that naturally occuring butterfly eyespots can increase survival even when they are constantly displayed and motionless.
Keywords: eyespot; intimidation hypothesis; Junonia almana; peacock pansy
Abstract
Eyespots have evolved in many lepidopteran insects, which suggests their adaptive value. One of their hypothesized functions is that predators are intimidated by prey with large and conspicuous eyespots and hence refrain from attacking them. Recent experiments have shown that a combination of eyespots and intimidating behaviour can increase survival. We tested whether the mere presence of conspicuous eyespots can thwart attacking birds, that is, when the eyespots are displayed constantly, without any intimidating behaviour. We used prey that consisted of wings of the peacock pansy butterfly, Junonia almana, glued onto a piece of cardboard so as to resemble a butterfly with its wings open. A mealworm was placed between the wings in place of the body. Great tits, Parus major, were used as the predator in the study and were offered a choice between two model prey, one with intact eyespots and one without. Prey with eyespots were attacked significantly fewer times than those without. The time between the first and second attack was longer when the prey without eyespots was attacked first. These results support the hypothesis that naturally occuring butterfly eyespots can increase survival even when they are constantly displayed and motionless.
Keywords: eyespot; intimidation hypothesis; Junonia almana; peacock pansy
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