A Supplemental Function of the Avian Egg Tooth

[摘要] Abstract. Hatchlings use egg teeth to help break through the shell during hatching, but these structures could have an additional function of increasing nestlings' visibility. I investigated the size, color, and persistence of egg teeth in woodpeckers, which nest in dark cavities. Many species of woodpecker have two egg teeth, one each on the tip of the maxilla and of the mandible, which, together with the pale flanges, frame the open mouth when nestlings gape. A spectrometer confirmed that reflectance of Northern Flicker (Colaptes auratus) egg teeth is higher than that of the flanges across a wide range of wavelengths, reaching nearly 100% reflectance in the wavelengths most visible to woodpeckers. Reflectance of flanges peaked in the ultraviolet, which is less visible to woodpeckers. Therefore, parent woodpeckers can probably see egg teeth better than flanges. Within a brood, the brightness of egg teeth or flanges was not dependent on nestlings' size (hatching order), suggesting these structures are not...

[学科分类] 动物科学

[关键词] Colaptes auratus;color;detectability;egg tooth;nestling;Northern Flicker;reflectance;woodpecker