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Relationship between the molt score of Northern Flickers banded at Manomet between 1968 and 2014 and the day of year. ASY individuals are identified by hollow circles. The data points were fitted to a simple linear regression that was used subsequently to estimate when the aberrant flickers would have deposited the red pigment. Bird with finished molts (scores of 0 or 100) were excluded from the fitted model. We also show 95% confidence intervals (stippled lines).
Source publication
Yellow-shafted Flickers (Colaptes auratus auratus subspecies group of the Northern Flicker) occasionally have orange to red flight feathers in eastern North America far from the hybrid zone with the Red-shafted Flicker (C. a. cafer subspecies group). Blocks of feathers of anomalous color tend to show bilateral symmetry and may differ from one year...
Contexts in source publication
Context 1
... primary molt score of Northern Flickers banded at Manomet varies as a function of day of year and can be approximated by the following linear regression: molt score ¼ 0.77 3 day of the year À 124 (r ¼ 0.90; Figure 6). The replacement of primaries occurs slightly earlier, is faster and less variable in AHY/ASY birds (slope ¼ 0.85, y 0 ¼À146; r ¼ 0.96, n ¼ 15) compared to HY/SY birds (slope ¼ 0.71, y 0 ¼ À108; r ¼ 0.86, n ¼ 87; Figure 6). ...
Context 2
... primary molt score of Northern Flickers banded at Manomet varies as a function of day of year and can be approximated by the following linear regression: molt score ¼ 0.77 3 day of the year À 124 (r ¼ 0.90; Figure 6). The replacement of primaries occurs slightly earlier, is faster and less variable in AHY/ASY birds (slope ¼ 0.85, y 0 ¼À146; r ¼ 0.96, n ¼ 15) compared to HY/SY birds (slope ¼ 0.71, y 0 ¼ À108; r ¼ 0.86, n ¼ 87; Figure 6). Because it was not always possible to determine the age of the flickers we examined, we used the regression for birds of all ages to estimate when the birds would have been depositing red pigments. ...
Similar publications
The study of avian integumentary colouration can offer insight into dietary and metabolic processes as well as fitness in focal species. Yet, we know relatively less about the system of feather colouration in African birds in comparison to Europe, North America and the neotropics. In this study, we biochemically characterised and quantified the pig...
Citations
... However, some studies have compiled the published sightings from particular groups or from particular localities (e.g., Alaja and Mikkola 1997, Konter 2015, Bond and Diamond 2016, Lee and You 2016, Mahabal et al. 2016, Abraham et al. 2020 or have performed intensive sampling to try to assess the frequency of atypical plumage in a species or clade (Jehl 1985, Møller et al. 2007, Martins-Silva et al. 2016. More rarely, studies will ask questions that move beyond sightings or frequencies of atypical individuals in the population (Hudon et al. 2017, Besozzi et al. 2021, Levinson et al. 2021, Camacho et al. 2022, Hudon and Pyle 2022, Ocampo et al. 2022. The rise in community-driven science presents an opportunity to study these sightings in large numbers in a way that was nearly impossible solely with museum holdings or an individual's own sightings (e.g., Leighton et al. 2016, Husby 2017, Izquierdo et al. 2018, Zbyryt et al. 2021. ...
Birds are known for their brilliant colors and extraordinary patterns. Sightings of individuals with atypical plumage often cause considerable excitement in the birding public, but receive little attention beyond reporting one-off sightings by the scientific community. In this Perspective, we argue that sightings of individuals with atypical plumage submitted to community science platforms hold the potential to further our understanding of the evolution of plumage color and patterning in birds. As a demonstration, we outline 2 examples using sightings of leucistic individuals—those that lack melanin across the body or in certain feather patches. First, we discuss the potential for understanding carotenoid pigmentation with these sightings. Leucism influences melanins, but not carotenoids, and so the extent and distribution of carotenoids across the body are unmasked. In a leucistic individual, carotenoids may or may not be more extensive than what is typically visible and this could help to understand the energetic costs and constraints involved in obtaining, processing, and depositing carotenoids in different species. Second, we discuss how partial leucism could provide insights into plumage pattern evolution. We demonstrate that one can use the many observations present on community science platforms to identify repeated patterns in different partially leucistic individuals of the same species, and match these to patches present in related species. These patterns could be the result of shared underlying genetic variation that controls plumage patterning in birds over long evolutionary timescales. With these examples, we outline a few potential lines of inquiry possible with atypical sightings submitted to community science platforms and note that other plumage aberrations provide additional opportunities. We encourage researchers to take full advantage of these chance sightings when they occur and database managers to make it possible to more easily tag photos of individuals with atypical plumage or other traits.
... The hues (for instance red, purple, or magenta) rhodoxanthin contribute to in different sources depend on different factors. Examples of this can be seen in the red hues of yew fruit (Schex et al., 2021), the purple shade of honeysuckle (Hudon et al., 2007), and the magenta coloring of various bird species' feathers (Hudon et al., 2017(Hudon et al., , 2020. Due to the long polyene chains in their structures, where π-electrons are highly delocalized, most carotenoids absorb blue and violet light (400-500 nm) and hence they exhibit colors ranging from yellow to red. ...
Background
The scientific evidence linking several diseases to human diet has highlighted the beneficial impacts of various natural food components, including carotenoids. The xanthophyll rhodoxanthin is a type of retrocarotenoid that might exert positive health-promoting actions.
Scope and approach
There is increasing evidence that rhodoxanthin exerts potential health-promoting biological activity in both in vitro and in vivo models, and some patents are available for food applications. However, as a food additive, rhodoxanthin is currently approved for use only in Australia and New Zealand. Considering the importance of carotenoids and their relevance to the market, this review provides a comprehensive description of natural rhodoxanthin, covering its distinctive properties and potential health-promoting actions. Moreover, the most promising advancements in the production, recovery, application and regulatory framework of this pigment from both plant and microbial sources are also considered. Lastly, we offer our expert perspective to the readers on the potential of rhodoxanthin as a prominent natural carotenoid in the food market.
Key findings and conclusions
It can be concluded that rhodoxanthin is a scarcely studied carotenoid with an unusual and interesting chemical structure that endows it with properties (such as color or antioxidant capacity) that are amenable for industrial applications in different sectors. The scarcity of studies about this carotenoid as well as its absence in common dietary sources offer both challenges and innovation opportunities. More research is needed to determine whether rhodoxanthin can ‘compete with’ or even ‘surpass’ carotenoids with a well-established market, such as canthaxanthin, lycopene or astaxanthin. Overall, we identify main knowledge gaps and research opportunities for application of rhodoxanthin in several industries.
... We scored plumage characters of historic and contemporary flickers on a categorical scale from 0 (pure yellow-shafted) to 4 (pure red-shafted) for each of the six plumage traits following a protocol slightly modified from Short (1965; see Fig. 1 and Table S1 for details), a method that has been used extensively within the flicker system (e.g., Moore and Buchanan 1985;Moore 1987;Wiebe 2000;Flockhart and Wiebe 2007;Aguillon et al. 2021). The main modification from Short (1965) is differences in our scoring of the shaft color based on an increased understanding of carotenoid pigmentation (e.g., Hudon et al. 2017): we account for the overall coloration of the shaft feathers and deemphasize solitary abnormal feathers and differences in color between the barb and shaft. We additionally calculated an overall plumage hybrid index by summing across the trait scores within each individual and dividing by 24 in males and 20 in females (the maximum possible) to obtain a score that ranges from 0 to 1. ...
Natural hybrid zones have provided important insights into the evolutionary process, and their geographic dynamics over time can help to disentangle the underlying biological processes that maintain them. Here, we leverage replicated sampling of an identical transect across the hybrid zone between yellow-shafted and red-shafted flickers in the Great Plains to assess its stability over ∼60 years (1955-1957 to 2016-2018). We identify a ∼73 km westward shift in the hybrid zone center towards the range of the red-shafted flicker, but find no associated changes in width over our sampling period. In fact, the hybrid zone remains remarkably narrow, suggesting some kind of selective pressure maintains the zone. By comparing to previous work in the same geographic region, it appears likely that the movement in the hybrid zone has occurred in the years since the early 1980s. This recent movement may be related to changes in climate or land management practices that have allowed westward movement of yellow-shafted flickers into the Great Plains. This article is protected by copyright. All rights reserved.
... Finally, occasional orange to red fl ight feathers in Yellow-shafted Flickers (Colaptes auratus auratus subspecies group) in eastern North America, far from the hybrid zone with the Redshafted Flicker (C. a. cafer subspecies group), were recently ascertained to be caused by rhodoxanthin, not genetic introgression (Hudon et al. 2017). It is apparent that any species of bird that normally has yellow carotenoids in its plumage, and which ingests Morrow's or Tatarian honeysuckle berries during feather molt, likely will have portions of its plumage imbued with unusual reddish tones. ...
... We identifi ed feathers suspected of carrying rhodoxanthin by applying a set of well-defi ned criteria that follow from our understanding of how rhodoxanthin gets incorporated into the plumage of birds (Völker 1955, Witmer 1996, Hudon et al. 2017). This largely permitted us to distinguish this process from other processes that could result in reddened feathers. ...
... As a corollary, we can expect much variation between individuals in the resulting color, depending on amount of berries consumed. The refl ectance spectrum of a rhodoxanthin-bearing feather may be expected to show a shoulder at about 570 nm (Hudon, Derbyshire et al. 2013, Hudon, Driver et al. 2017). ...
Many species normally bright yellow have been turning up with abnormal orange-to-red feathers in eastern North America and the American Midwest. In addition to the well-documented orange tail-banded Cedar Waxwings, aberrantly reddened feathers have been recorded on Yellow-breasted Chat, Kentucky Warbler, White-throated Sparrow, Baltimore Oriole and Northern Flicker. The birds are suspected of having acquired a carotenoid of deep red color (rhodoxanthin) from their diet, likely from the berries of two species of exotic bush honeysuckles (Morrow’s and Tatarian honeysuckle and their hybrids) now well established throughout eastern and midwestern North America. Using a set of well-defined criteria, we have compiled a preliminary list of species, plumages, feathers, and feather tracts likely affected by the unusual carotenoid, and the U.S. states and Canadian provinces where they occur. To accomplish this, we consulted banders at banding stations and browsed images of birds posted on the World Wide Web. We report instances of obvious reddening of the plumage (i.e., erythrism) or the presence of rhodoxanthin in 15 species of birds, including several that ingest fruits only sporadically or seasonally, over a span of at least five decades. Our summary includes many examples of aberrantly colored birds in eastern North America, including southern Canada, and the Midwest, but also farther west (Alberta, Montana and Idaho) and in southern areas where these birds overwinter.
... Finally, occasional orange to red fl ight feathers in Yellow-shafted Flickers (Colaptes au- ratus auratus subspecies group) in eastern North America, far from the hybrid zone with the Red- shafted Flicker (C. a. cafer subspecies group), were recently ascertained to be caused by rhodoxan- thin, not genetic introgression ( Hudon et al. 2017). It is apparent that any species of bird that normally has yellow carotenoids in its plumage, and which ingests Morrow's or Tatarian honeysuckle berries during feather molt, likely will have portions of its plumage imbued with unusual reddish tones. ...
... We identifi ed feathers suspected of carrying rho- doxanthin by applying a set of well-defi ned cri- teria that follow from our understanding of how rhodoxanthin gets incorporated into the plumage of birds (Völker 1955, Witmer 1996, Hudon et al. 2017). This largely permitted us to distinguish this process from other processes that could result in reddened feathers. ...
... As a corollary, we can expect much variation between individu- als in the resulting color, depending on amount of berries consumed. The refl ectance spectrum of a rhodoxanthin-bearing feather may be expected to show a shoulder at about 570 nm (Hudon, Derbyshire et al. 2013, Hudon, Driver et al. 2017). ...
Many species normally bright yellow have been turning
up with abnormal orange-to-red feathers in eastern
North America and the American Midwest. In
addition to the well-documented orange tail-banded
Cedar Waxwings, aberrantly reddened feathers have
been recorded on Yellow-breasted Chat, Kentucky
Warbler, White-throated Sparrow, Baltimore Oriole
and Northern Flicker. The birds are suspected of
having acquired a carotenoid of deep red color (rhodoxanthin)
from their diet, likely from the berries of
two species of exotic bush honeysuckles (Morrow’s
and Tatarian honeysuckle and their hybrids) now
well established throughout eastern and midwestern
North America. Using a set of well-defi ned criteria,
we have compiled a preliminary list of species, plumages,
feathers, and feather tracts likely aff ected by the
unusual carotenoid, and the U.S. states and Canadian
provinces where they occur. To accomplish this, we
consulted banders at banding stations and browsed
images of birds posted on the World Wide Web. We
report instances of obvious reddening of the plumage
(i.e., erythrism) or the presence of rhodoxanthin in 15
species of birds, including several that ingest fruits
only sporadically or seasonally, over a span of at least
fi ve decades. Our summary includes many examples
of aberrantly colored birds in eastern North America,
including southern Canada, and the Midwest,
but also farther west (Alberta, Montana and Idaho)
and in southern areas where these birds overwinter.
... Visual chromophore: the part of a molecule responsible for its color. species changed from orange/yellow to deeper red [24,25]. This strong environmental influence on carotenoid expression is one reason why identifying the genetic bases of carotenoid traits has long been challenging. ...
Coloration is one of the most conspicuous traits that varies among organisms. Carotenoid pigments are responsible for many of the red, orange, and yellow colors in the natural world and, at least for most animals, these molecules must be acquired from their environment. Identifying genes important for carotenoid transport, deposition, and processing has been difficult, in contrast to the well-characterized genes involved in the melanogenesis pathways. We review recent progress in the genetics of carotenoid processing, advances owing in part to the application of high-throughput sequencing data. We focus on examples from several classes of genes coding for scavenger receptors, β-carotene oxygenases, and ketolases. We also review comparative studies that have revealed several important findings in the evolution of these genes. Namely, that they are conserved across deep phylogenetic timescales, are associated with gene/genome duplications, and introgression has contributed to their movement between several taxa.
Taxus baccata L., an evergreen tree, was known until recently due to its high concentration of toxic compounds. The purpose of the present study was to focus on the only non-poisonous part, the red arils, which have recently been described as an important source of various bioactive constituents. To establish total phenolic, flavonoid, and carotenoid content, antioxidant capacity, and cytotoxic properties, two types of extracts were obtained. The chemical profile of the ethanolic extract was evaluated using chromatographic (HPLC-DAD-ESI+) and spectral (UV-Vis) methods, and the antioxidant activity of the ethanolic extract was assessed using DPPH and FRAP assays, yielding moderate results. In the second type of extract (methanol: ethyl acetate: petroleum ether (1:1:1, v/v/v)) we identified three carotenoids using open column chromatography and RP–PAD–HPLC, with rhodoxanthin being the most abundant. Considering the above and mainly because of the lack of information in the literature about this pigment and its biological effects, we decided to further investigate the cytotoxic activity of rhodoxanthin, the main carotenoid presented in aril, and its protective effect against H2O2-induced oxidative stress using two cell lines: human HaCaT keratinocytes and B16F10 murine malignant melanoma. The MTT and Annexin-V Apoptosis assays showed a substantial cytotoxic potential expressed in a dose-dependent manner towards the melanoma cell line, however, no obvious cytotoxic effects on human keratinocytes were noticed.
Carotenoid pigments serve many endogenous functions in organisms, but some of the more fascinating are the external displays of carotenoids in the colorful red, orange and yellow plumages of birds. Since Darwin, biologists have been curious about the selective advantages (e.g., mate attraction) of having such ornate features, and, more recently, advances in biochemical methods have permitted researchers to explore the composition and characteristics of carotenoid pigments in feathers. Here we review contemporary methods for extracting and analyzing carotenoids in bird feathers, with special attention to the difficulties of removal from the feather keratin matrix, the possibility of feather carotenoid esterification and the strengths and challenges of different analytical methods like high-performance liquid chromatography and Raman spectroscopy. We also add an experimental test of current common extraction methods (e.g., mechanical, thermochemical) and find significant differences in the recovery of specific classes of carotenoids, suggesting that no single approach is best for all pigment or feather types.
