The evolution of plumage colouration in parrots: a review

Abstract

The plumages of parrots provide some of the most striking colouration in nature. We summarise the diversity of mechanisms producing colour in parrots and the current evidence for the adaptive significance of variation in the colour of parrot plumages. Only recently have detailed studies begun to unravel the mechanisms of their colour-production and colourvision systems. Parrots produce much of their plumage colouration through a unique suite of pigments (psittacofulvins), or through a feather tissue nanostructure that results in coherent scattering of light, or a combination of the two (producing green). Psittacofulvins are found nowhere else in nature, and may even generate fluorescence in many parrot species. Compared with other avian taxa, the adaptive significance of parrot plumage colouration remains poorly understood, although some studies suggest that plumage colouration may form important sexual signals and may be used in mate-choice by several species. There is evidence to suggest that parrot colouration can be subject to both environmental and genetic control. We emphasise that parrots offer a distinctive and useful colouration system for further study. Further research is required to unravel how the dramatic colour patterns of parrots evolved, and what roles colour signals may play in the life histories of parrots.

Spectral tuning of Amazon parrot feather coloration by psittacofulvin pigments and spongy structures

“…Parrots are well known for their striking, bright coloration (Berg and Bennett, 2010). When at rest, most Amazon parrots show a predominantly green colour ( Fig.…”

“…As a consequence, only the long-wavelength part of broad-band incident light remains as back-scattered, reflected light. However, the colour of blue feathers is called a structural colour, because it originates from unpigmented, nano-sized, spongy-structured cells that selectively reflect short-wavelength light by constructive interference (Shawkey et al, 2003;Prum, 2006;Kinoshita et al, 2008;Berg and Bennett, 2010;Stavenga et al, 2011b). The green feathers also have spongy cells, which reflect blue-green light.…”

“…The green feathers also have spongy cells, which reflect blue-green light. A blue-absorbing pigment, which functions as a short-wavelength filter, restricts the wavelength range of the reflected light, resulting in green coloured feathers (Berg and Bennett, 2010;D'Alba et al, 2012;Saranathan et al, 2012).…”

How parrots see their colours: novelty in the visual pigments ofPlatycercus elegans

“…Platycercus elegans elegans occupies mesic wooded and forest habitats, and P. e. flaveoulus riparian habitats (Forshaw and Cooper, 2002), and the distribution of the two overlaps in a hybrid zone (Joseph et al, 2008). The complex also includes the phenotypically intermediate and clinally varying P. e. adelaidae subspecies, in which there is much plumage colour variation between individuals in the same local area (Forshaw and Cooper, 2002;Joseph et al, 2008;Berg and Bennett, 2010). Platycercus elegans is perhaps the most colour variable of the ~350 species of parrot worldwide, and Mayr (Mayr, 1963) considered the species an example of a circular overlapping or 'ring' species (Irwin and Irwin, 2002), of which there are few worldwide.…”

Survey duration and season influence the detection of introduced eastern rosella (Platycercus eximius) in New Zealand

“…There are a number of species-typical behavioural barriers to reliably detecting eastern rosella (hereafter rosella) across the New Zealand landscape. Superficially, it may seem that rosella have a high probability of detection, being both visually and vocally conspicuous to the human observer (Berg and Bennett 2010). When silent and stationary in foliage, however, these birds can be extremely difficult to detect ; other studies have also noted the difficulty of detecting seemingly conspicuous parrots in dense vegetation (Heinsohn et al 2005;Rivera-Milan et al 2005).…”