Ophthalmology of Psittaciformes: Parrots and Relatives

Moore, Bret A.; Oriá, Arianne Pontes; Montiani‐Ferreira, Fabiano

doi:10.1007/978-3-030-71302-7_17

Cited by 3 publications

(5 citation statements)

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“…African Pied Starlings have been observed contracting and dilating their pupils during food exchanges, with the donor widening its pale iris and the recipient narrowing theirs (Craig 2022). Similarly, contraction of the pupil to accentuate the iris ('eye-blazing' or 'eye-pinning') is common in parrots, and this behaviour is associated with excited states including social dominance interactions and courtship displays (Hardy 1963, Smith 1975, Moore et al 2022. Similar behaviours have been observed in other families and may prove to be widespread across light-eyed birds (McIlhenny 1937, Hardy 1974, Craig & Hulley 2004.…”

Section: Social Signallingmentioning

confidence: 78%

“…Similarly, contraction of the pupil to accentuate the iris (‘eye‐blazing’ or ‘eye‐pinning’) is common in parrots, and this behaviour is associated with excited states including social dominance interactions and courtship displays (Hardy 1963, Smith 1975, Moore et al . 2022). Similar behaviours have been observed in other families and may prove to be widespread across light‐eyed birds (McIlhenny 1937, Hardy 1974, Craig & Hulley 2004).…”

Section: Evolutionary Drivers Of Bird Eye Colourmentioning

confidence: 99%

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The mechanistic, genetic and evolutionary causes of bird eye colour variation

Corbett,

Brumfield,

Faircloth

2023

Ibis

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Birds display a rainbow of eye colours, but this trait has been little studied compared with plumage coloration. Avian eye colour variation occurs at all phylogenetic scales: it can be conserved throughout whole families or vary within one species, yet the evolutionary importance of this eye colour variation is under‐studied. Here, we summarize knowledge of the causes of eye colour variation at three primary levels: mechanistic, genetic and evolutionary. Mechanistically, we show that avian iris pigments include melanin and carotenoids, which also play major roles in plumage colour, as well as purines and pteridines, which are often found as pigments in non‐avian taxa. Genetically, we survey classical breeding studies and recent genomic work on domestic birds that have identified potential ‘eye colour genes’, including one associated with pteridine pigmentation in pigeons. Finally, from an evolutionary standpoint, we present and discuss several hypotheses explaining the adaptive significance of eye colour variation. Many of these hypotheses suggest that bird eye colour plays an important role in intraspecific signalling, particularly as an indicator of age or mate quality, although the importance of eye colour may differ between species and few evolutionary hypotheses have been directly tested. We suggest that future studies of avian eye colour should consider all three levels, including broad‐scale iris pigment analyses across bird species, genome sequencing studies to identify loci associated with eye colour variation, and behavioural experiments and comparative phylogenetic analyses to test adaptive hypotheses. By examining these proximate and ultimate causes of eye colour variation in birds, we hope that our review will encourage future research to understand the ecological and evolutionary significance of this striking avian trait.

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Section: Social Signallingmentioning

confidence: 78%

Section: Evolutionary Drivers Of Bird Eye Colourmentioning

confidence: 99%

The mechanistic, genetic and evolutionary causes of bird eye colour variation

Corbett,

Brumfield,

Faircloth

2023

Ibis

View full text Add to dashboard Cite

show abstract

“…African Pied Starlings have been observed contracting and dilating their pupils during food exchange interactions, with the donor widening their pale irises and the recipient narrowing them (Craig 2022). Similarly, contraction of the pupil to accentuate the iris is common in parrots, where it is called "eye-blazing" or "eye-pinning", and this behavior is associated with excited states including social dominance interactions and courtship displays (Hardy 1963, Smith 1975, Serpell 1982, 1989Courtney 1997a, b;Marcuk et al 2020, Moore et al 2022). Similar behaviors have been observed in other families and may prove to be widespread across lighteyed birds (McIlhenny 1937, Hardy 1974, Craig and Hulley 2004.…”

Section: Social Signalingmentioning

confidence: 99%

Bird Eye Color: A Rainbow of Variation, a Spectrum of Explanations

Corbett¹,

Brumfield²,

Faircloth³

2022

Preprint

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Birds display a rainbow of eye colors, but this trait has received relatively little study compared to plumage coloration. Avian eye color variation occurs at all phylogenetic scales: it can be conserved throughout whole families or vary within a single species, yet the evolutionary importance of eye color variation within species and across the avian phylogeny is also understudied. Here, we provide an overview of eye color variation in birds, summarizing the state of knowledge about its causes at three primary levels: mechanistic, genetic, and evolutionary. Mechanistically, we show that common avian iris pigments include melanin and carotenoids, which also play major roles in plumage color, as well as purines and pteridines, which are found as pigments primarily in non-avian taxa. Genetically, we examine known associations between genes and eye color, primarily identified from classical breeding studies and recent genomic work in domesticated species. Finally, from an evolutionary standpoint, we present and discuss several hypotheses explaining the adaptive significance of eye color variation. Many of these suggest bird eye color plays an important role in intraspecific signaling, particularly as an indicator of age or mate quality, although the importance of eye color may differ between species and few evolutionary hypotheses have been directly tested. We suggest that future studies of avian eye color should focus on all three levels, including broad-scale iris pigment analyses across bird species, genome sequencing studies to identify loci associated with eye color variation, and behavioral experiments and comparative phylogenetic analyses to test adaptive hypotheses. By examining these proximate and ultimate causes of eye color variation in birds, we hope that our review will spur future research to understand the ecological and evolutionary significance of this striking avian trait.

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“…Unlike the smooth muscle bers in the iris of mammals (Huber et al, 2007), those of birds are predominantly striated (Coli et al, 2016), suggesting that avian pupil size changes can be under voluntary control. Numerous lay reports also note the propensity of Psittacidae (parrots) to change pupil size rapidly as part of visually striking displays, known as "eye pinning" or "eye ashing", which is also associated with agonistic behavior, happiness or excitement (Hardy, 1963;Smith 1973;Marcuk et al, 2020;Moore et al, 2022). In short, regardless of the voluntary or involuntary nature of pupil size changes in birds, these appear to comply with communicative functions for the external eye appearance either as part of displays or by enabling the inference of internal states and emotions.…”

Section: Introductionmentioning

confidence: 99%

“…Based on that, Davidson et al (2014) suggested that conspicuous eyes can be seen outside of the nest, so it is a useful signal to prevent con ict. Adding to the ways in which birds may use eyes in conspeci c signaling, a growing number of studies report that birds can voluntarily change their pupil size during social interaction associated with agonistic behavior, happiness, or excitement (Marcuk et al, 2020;Moore et al, 2022). One study shows that, in Japanese quails, increases in pupil size can be observed during pleasant behavioral sequences like dustbathing (Bertin et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Photopic factors influence external eye appearance in parrots (Psittaciformes)

Duran

García

Piepenbrock

et al. 2023

Preprint

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External eye appearance in diverse avian taxa has been proposed to be driven by social and ecological functions in different studies. Recent research using quantitative measurements and phylogenetically informed analyses in primates suggest that instead photoprotective functions are important drivers of external eye appearance. Using similar methods, we examine the variation in external eye appearance of 132 parrot species (Psittaciformes) in relation to their ecology and sociality. Breeding systems, flock size and sexual dimorphism, as well as species’ latitude and maximum flying altitude were used to explore the relative contribution of social and ecological factors in driving external eye appearance. We measured the hue and brightness of visible parts of the eye and the difference in measurements of brightness between adjacent parts of the eye. While we found no link between social variables and our measurements, we found a significant negative association between the brightness of the inner part of the iris and latitude and altitude. Darker inner parts of the irises were more prevalent farther away from the equator and with higher flying altitudes. Because the amount of UV radiation varies according to these factors, our results suggest that irises are at least partially adapted for photoprotective functions. The results inform our growing understanding of the drivers of external eye appearance across land vertebrates, highlighting the importance of photopic factors across such distantly related taxa as anthropoid primates and psittaciformes.

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Ophthalmology of Psittaciformes: Parrots and Relatives

Cited by 3 publications

References 123 publications

The mechanistic, genetic and evolutionary causes of bird eye colour variation

The mechanistic, genetic and evolutionary causes of bird eye colour variation

Bird Eye Color: A Rainbow of Variation, a Spectrum of Explanations

Photopic factors influence external eye appearance in parrots (Psittaciformes)

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