Sexual Dichromatism in the Blue-fronted Amazon Parrot (Amazona aestiva) Revealed by Multiple-angle Spectrometry

  title={Sexual Dichromatism in the Blue-fronted Amazon Parrot (Amazona aestiva) Revealed by Multiple-angle Spectrometry},
  author={Susana I. C. O. Santos and Brian Elward and Johannes T. Lumeij},
Abstract Seventy-five percent of psittacine species, including the blue-fronted Amazon parrot (Amazona aestiva), are classified as sexually monomorphic. However, this classification is based on the inability of the trichromatic human eye to perceive light in the near-ultraviolet spectrum. Spectrometry is a technique that enables humans to recognize the increased range of color perceived by the tetrachromatic avian eye. By using this technique, researchers have reclassified many avian species as… 

Viability of sex identification of the blue-fronted Amazon parrot (Amazona aestiva) based on iris color sexual dichromatism.

The viability of sex identification by direct observation of iris sexual dichromatism is analyzed, comparing suggestions by professionals familiarized with the species to molecular sexing by Polymerase Chain Reaction (PCR) and measuring color similarity between individuals using digital colorimetry.

Sexual dimorphism and determination of sex by morphometries in Blue-fronted Amazons (Amazona aestiva)

Blue-fronted Amazons are sexually dimorphic for most characteristics of body size and show sexual dichromatism in the colour of the plumage of the head, which allows determination of sex of individuals by morphological variables that can be easily measured in the field.

Hidden dichromatism in the Burrowing Parrot (Cyanoliseus patagonus) as revealed by spectrometric colour analysis

Spectrometry revealed that Burrowing Parrot is among the growing number of bird species which were formerly classed as sexually monochro- matic based on human vision, but which are actually sexually dichromatic.

Hidden dichromatism in the Burrowing Parrot ( Cyanoliseus patagonus ) as revealed by spectrometric colour analysis

Spectrometry revealed that Burrowing Parrot is among the growing number of bird species which were formerly classed as sexually monochromatic based on human vision, but which are actually sexually dichromatic.

Size dimorphism and avian‐perceived sexual dichromatism in a New Zealand endemic bird, the whitehead Mohoua albicilla

It is suggested that the extent of sexual plumage dichromatism is pronounced and can be perceived by these birds, and although sexual dimorphism was also detectable in the mass among the DNA‐sexed individuals, it was found to be less extensive than previously thought.

Subtle sexual plumage color dimorphism and size dimorphism in a South American colonial breeder, the Monk Parakeet (Myiopsitta monachus)

The spectrophotometric results indicate that the Monk Parakeet shows subtle sexual plumage color dimorphism in three out of twelve body regions, and the morphometric analysis showed that there are subtle sex differences in body size (bill and weight).

Comparison of multiple-angle spectrometry of plumage versus individual feathers for the assessment of sexual dichromatism in the long-tailed finch (Poephila acuticauda)

This study shows how some plumage characteristics may be overviewed if single unidirectional reflectance spectrometry is used and shows that results obtained from measuring the plumage and individual feathers lead to different conclusions.

Feather morphological predictors of angle-dependent color changes in parrot plumage

Non-iridescent angle-dependent coloration from the tail and wing feathers of several parrot species is described for the first time and these findings deepen the views on the importance of microscopic feather features in the production of directional animal coloration, especially in tissues that are colored predominantly by pigments and appear to be statically colored.

Análise cognitiva de papagaios (Amazona aestiva), Psittaciformes, de cativeiro e de vida livre através de testes de inteligência

Birds have shown to be able to solve many problems that were previously only attributed to primates, suggesting that their cognitive ability is far greater than imagined. The Blue-fronted-parrots

The evolution of plumage colouration in parrots: a review

This work summarises the diversity of mechanisms producing colour in parrots and the current evidence for the adaptive significance of variation in the colour of parrot plumages, and emphasises that parrots offer a distinctive and useful colouration system for further study.



Sexual dichromatism in the yellow-breasted chat Icteria virens: spectrophotometric analysis and biochemical basis

An unbiased assessment of plumage dichromatism in the yellow-breasted chat Icteria virens is presented, which indicated that the plumage pigmentation consisted solely of the carotenoid all-trans lutein and it was found that males have higher concentrations of plumagesCarotenoids than females.

Individual color variation and male quality in pied flycatchers (Ficedula hypoleuca): a role of ultraviolet reflectance

The results suggest that in pied flycatcher males, the UV reflectance of plumage may be positively correlated with individual quality.

Differential effects of endoparasitism on the expression of carotenoid- and melanin-based ornamental coloration

  • K. McGrawG. Hill
  • Biology
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 2000
It is found that the carotenoid–based plumage and bill coloration of parasitized males was less saturated than that developed by unparasitized males, but that the brightness and size of melanin–based black caps did not differ between the groups.

Ultraviolet sexual dimorphism and assortative mating in blue tits

It is concluded that blue tits are markedly sex dimorphic in their own visual world, and that UV/violet coloration probably plays a role in blue tit mate acquisition.


It is shown that the plumage coloration of the Picui Dove is clearly sexually dimorphic, and studies of sexual selection in this and related species should measure sexual dichromatism objectively, and should not rely on human color perception.

Ultraviolet vision, fluorescence and mate choice in a parrot, the budgerigar Melopsittacus undulatus

This study provides convincing evidence that UV reflectances can play a role in mate choice in non–passerines, but no evidence that the yellow fluorescence observed under UVA illumination is itself important as a signal.

Ornamental non-carotenoid red feathers of wild burrowing parrots

Bird plumage colors have the potential to indicate individual quality, condition, health, immunocompetence, or the extend of parental care, and the relationships between objectively assessed plumage color and body size, body condition, breeding success and nestling growth in wild Psittaciformes are investigated.

Paternity analysis reveals opposing selection pressures on crown coloration in the blue tit (Parus caeruleus)

It is shown that males with a more UV–shifted crown hue were less cuckolded, which probably resulted from female preference for more ornamented mates, and two alternative male mating tactics, where more UV-ornamented males maximize within–pair success and less UV–ornamente males maximize extra-pair success.

Sexual Selection and the Mismeasure of Color

It is argued that the error in this assumption that birds see color patterns as humans do may well be a major reason that support for various evolutionary hypotheses involving color is an area of controversy, and suggests methods for overcoming the shortcomings of existing studies.

Blue tits are ultraviolet tits

Reflectance spectrophotometry reveals that blue tit plumage shows considerable reflection of UV light, and sexually dichromatic for multiple regions of plumage, including the crest, which has implications for both intra– and interspecific studies of sexual selection.