Research press release


Scientific Reports

Animal behaviour: Birds have a pecking order for fruits


今回、Rui-Chang Quanたちは、中国南部で果実を常食とする4種の鳥類を対象として、それぞれ5色の人工果実と自然に成熟した果実を使って、色の好みを評価した。人工果実は、リンゴ、西洋ナシ、バナナ、コムギ、トウモロコシ粉を混ぜて作られており、黒、赤、黄、緑、青の5色で染色され、それと同時に、同じ5色の自然に成熟した果実も使用された。その結果、野生で捕獲された鳥と飼育下の鳥のいずれも一貫して黒と赤に対する強い選択性を示し、(人工果実、天然の果実のいずれにおいても)緑のような珍しい色の果実を避けていた。中国南部では、果実の色として最も多いのが黒と赤だ。


When it comes to picking fruit, tropical Asian birds seem to favour red and black fruits according to an investigation published in Scientific Reports. These are the most common colours of fruits that are chiefly dispersed by birds; thus, the observations suggest that fruit colours have evolved, to some extent, to attract birds.

Rui-Chang Quan and colleagues evaluated the preferences of four species of fruit-eating birds from southern China for artificial and natural ripe fruit of five different colours. Artificial fruits were made from a mixture of apple, pear, banana, wheat and corn flour, and were dyed black, red, yellow, green or blue, matching the colours of the natural ripe fruits used. They found that both wild-caught and hand-reared birds had a consistent and strong preference for black and/or red colours, which are most common in the region, and avoid the uncommon colours, such as artificially and naturally green fruits.

The authors note that compared with other colours, red and black fruits stand out the most against the background used in the experiments, and acknowledge that contrast as well as colour may have influenced their results. However, their findings support the hypothesis that black and red fruits are common because, in part, fruit-eating birds prefer these colours.

doi: 10.1038/srep05627

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