Strategies of dynamic plumage colour change : a field experiment to test costs of intermediate coloration

许多脊椎动物的雄性表现出性别二型性和在性内选择的选择压力下进化出的雄性特有特征。在鸟类中，许多鸟类具有性别二色性，它们的雄性有鲜艳的羽毛。然而，一些鸟类的年轻雄性并不具有明显的外表，看起来与雌性非常相似。换句话说，年轻的男性拥有“中等智商”。年轻雄性的暗淡羽毛可能有特定的好处和代价，这与那些羽毛鲜艳的雄性不同。本研究重点研究了蓝鳍金枪鱼羽毛变暗的影响。进行了野外实验：将两种特殊的填充模型，一种是亮蓝色的雄性模型，另一种是迟钝的模型，赠送给了袋鼠的领地所有者。领地所有者对每种模式表现出不同的反应。综上所述，丛林鸟的羽毛颜色可能是雄鸟相互作用的状态信号。

Males of many vertebrates show sexual dimorphism and male-specific traits evolved by selection pressure of intra-sexual selection. In avian species, many birds have sexual dichromatism and their males have bright plumages. However, young males of some avian species do not possess conspicuous appearances and appear quite similar to females. In other words, young males have "intermediate brightness". The young male's dull plumage may have specific benefit and cost, which are different compared to those males of bright plumages. This study focused on the effect of the dull plumages in the Tarsiger cyanurus. A field experiment was performed: two types of special stuffed models, a bright blue male model and a dull model, were presented to territory owners of bushrobins. Territory owners showed different responses to each models. In conclusions, plumage colours of the bushrobin may have a status signal for male-male interaction.