Carotenoid-based colours are recognized as having an important signalling function, yet the nature of the mechanisms that maintain their honesty is not well understood. By combining a carotenoid-feeding experiment with a quantitative genetic experiment in a wild population of blue tits (Parus caeruleus), we were able to test predictions that differentiate between proposed mechanisms. If variati...

To understand how bees, birds, and fish may use colour vision for food selection and mate choice, we reconstructed views of biologically important objects taking into account the receptor spectral sensitivities. Reflectance spectra of flowers, bird plumage, and fish skin were used to calculate receptor quantum catches. The quantum catches were then coded by “red,” “green,” and “blue” of a compu...

We document a case of intraspecific variation in plumage colouration in Bearded Vultures that may have arisen as a functional response to climate conditions. Two subspecies, Gypaetus barbatus barbatus (Eurasia and North Africa populations) and Gypaetus barbatus meridionalis (Eastern and Southern Africa), have been described on the basis of plumage colour differences. The plumage of G. b. barbat...

Colour signals are expected to match visual sensitivities of intended receivers. In birds, evolutionary shifts from violet-sensitive (V-type) to ultraviolet-sensitive (U-type) vision have been linked to increased prevalence of colours rich in shortwave reflectance (ultraviolet/blue), presumably due to better perception of such colours by U-type vision. Here we provide the first test of this wid...

The White-naped Xenopsaris albinucha is an uncommon suboscine passerine with a disjunct distribution extending from Venezuela to the Southern Cone of South America. ornithological literature concerning this species contains contradictory claims about potential migratory movements, although most authors consider it be sedentary. In addition, observations exhibiting mix male- and female-like plum...

A participatory rural appraisal technique (PRAT) was used to obtain information from 132 randomly selected turkey farmers in two out of four agricultural development zones in Kwara state, Nigeria. Data were obtained on socio-occupational status of farmers, their production objectives, experience, flock structure, management practices, marketing and consumption of turkey eggs. The results showed...

The propensity of migratory waders to remain on the non-breeding grounds during the arctic breeding season (‘‘oversummer’’) in their first biological year of life (‘‘juveniles’’) may be latitude, and thus migratory distance dependent. We compared the extent of preparation for northward migration of western sandpipers Calidris mauri spending the non-breeding season in México and Panamá during 19...

Abstract Plumage colouration is important for birds as it helps them in camouflage, mate selection, social signalling and various other physiological behavioural processes. The most common pigments responsible are melanins carotenoids. In a few individuals, disrupted due to causes. colour aberrations found leucism, albinism, melanism, carotenism, schizochroism dilution whereas xanthochroism les...

In many birds, red, orange and yellow feathers are coloured by carotenoid pigments, but parrots are an exception. For over a century, biochemists have known that parrots use an unusual set of pigments to produce their rainbow of plumage colours, but their biochemical identity has remained elusive until recently. Here, we use high-performance liquid chromatography to survey the pigments present ...