以鸟类视觉模型揭示中杜鹃对冠纹柳莺的卵色模拟(英文)
Visual modeling reveals cryptic aspect in egg mimicry of Himalayan Cuckoo (Cuculus saturatus) on its host Blyth’s Leaf Warbler (Phylloscopus reguloides)
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摘要: 于2009年4—7月, 采用光谱仪量化卵色和建立鸟类视觉模型的方法, 在贵州宽阔水自然保护区对中杜鹃(Cuculus saturatus)寄生冠纹柳莺(Phylloscopus reguloides)的卵色模拟进行了研究。中杜鹃产白色卵带极少数而微小的棕色斑, 明显大于宿主卵, 重2.06 g, 体积1.91 cm3。从人眼看, 中杜鹃卵对宿主卵在很大程度上是模拟的, 但视觉模型表明, 两者的卵色在色调和色度上都完全分离, 揭示了人眼探测不到的卵色模拟情况。该文首次对中杜鹃的雏鸟特征进行描述, 在4日龄以后雏鸟嘴裂中出现三角形黑斑, 并随着日龄的增长而更加明显, 这种特征在霍氏中杜鹃(C. optatus)的雏鸟中也存在, 但未见于其他种类的杜鹃雏鸟。Abstract: Brood parasitism and egg mimicry of Himalayan Cuckoo (Cuculus saturatus) on its host Blyth’s Leaf Warbler (Phylloscopus reguloides) were studied in south-western China from April to July 2009. The cuckoo laid a white egg with fine brown markings on the blunt end. The eggs were conspicuously bigger than the host’s own, with 2.06 g in mass and 1.91 cm3 in volume. Visual modeling showed that the cuckoo eggs, which from the human eye appeared to mimic the host eggs to a great extent, were completely different from the host eggs in both hue and chroma. The characters of the Himalayan Cuckoo nestling, reported for the first time, included two triangular and black patches on its gape, which appeared from four days old and became darker with age and growth. While this character also exists in nestlings of Oriental Cuckoo (C. optatus), it has not been found for other Cuculus species. Our results reveal cryptic aspects in the cuckoo-host egg color matching, which are not visible to the naked human eye, and indicate that high mimetic cuckoo eggs rejected by hosts, as determined by human observers in previous studies, might not be mimetic as birds see them.