Читать книгу Bird Senses - Graham R. Martin - Страница 48

It is clear that many birds detect light over a wider range of wavelengths than humans are able to; in other words, they have a broader visible spectrum. Also, it seems that birds may be able to discern more colours within their spectrum; that is, they can probably make finer colour discriminations, at least in some parts of the spectrum. Some birds can detect light in the ultraviolet (UV) part of the spectrum, light to which human vision is insensitive. However, vision in the UV part of the spectrum is not unique to birds, for some terrestrial mammals and many invertebrates are also able to detect information using UV light.

It is important to note that not all birds see in the UV part of the spectrum. In fact those bird species which have true UV vision are found only in the gulls (Laridae, Charadriiformes), ostriches (Struthioniformes), parrots (Psittaciformes), and the oscine passerines (Passeriformes), but excluding the crows (Corvidae). Other bird species may have visual sensitivity that extends into the violet spectrum, but they cannot be considered truly UV-sensitive, while others, notably some birds of prey, have optical systems that filter out UV light from the image so that it never reaches the retina.