Search

ABSTRACT Colorful traits play an important role in animal communication. Melanin‐based colorations are the most extended color traits in animals and are produced by two types of endogenous melanic pigments: eumelanins and pheomelanins, the last ones being the least studied in the context of communication. The production of pheomelanin requires a semi‐essential amino acid, cysteine, which is also used for the synthesis of an important endogenous antioxidant, glutathione. Hence, it has been proposed that the synthesis of pheomelanin and glutathione may compete for the cysteine available in the organism. In that case, pheomelanic colorations are predicted to be less intense when the individual is facing an oxidative challenge, and therefore, they would provide information on the oxidative status of the bearer. Here, we experimentally evaluated this hypothesis using male Japanese quails (Coturnix japonica) as a model of study, a species with pheomelanin‐based plumage in the breast and cheeks. During feather growth, individuals were exposed to one of three possible conditions: Control (saline), an endogenous oxidative challenge (Escherichia coli lipopolysaccharide injections), or an exogenous oxidative challenge (paraquat injections). Contrary to predictions, we found that: (1) Birds from the three groups exhibited less intense pheomelanic colorations in feathers after the experimental manipulation, and the magnitude of this change did not differ among groups. (2) There was no effect of the experimental treatments on the proportion reduced/oxidized glutathione, an index of oxidative status. (3) Lipid peroxidation was lower after the experimental manipulation, with birds exposed to the paraquat challenge experiencing a stronger decline than other groups. (4) Cysteine and total glutathione levels decreased after the experimental manipulation, with no differences per group in the magnitude of the decline. Taken together the results do not support the hypothesis that oxidative status plays a key role at determining the variation in the intensity of pheomelanic colorations. [ABSTRACT FROM AUTHOR]

ABSTRACT Expression of vibrant plumage color plays important communication roles in many avian clades, ranging from penguins to passerines, but comparatively less is known about color signals in parrots (order Psittaciformes). We measured variation in coloration from three plumage patches (red face, blue rump, red tail) in an introduced population of rosy‐faced lovebirds (Agapornis roseicollis) in Phoenix, Arizona, USA and examined color differences between the sexes and ages as well as relationships with several indices of quality, including disease presence/absence (infection with beak and feather disease, Circovirus parrot, and a polyomavirus, Gammapolyomavirus avis), nutritional state (e.g., blood glucose and ketone levels), and habitat type from which birds were captured. We found that different plumage colors were linked to different quality indices: (a) adults had redder faces than juveniles, and birds with brighter faces had lower glucose levels and were less likely to have polyomavirus; (b) males had bluer rumps than females; and (c) birds caught farther from the city had redder and darker tail feathers than those caught closer to the urban center. Our findings reveal diverse information underlying variation in the expression of these disparate, ornate feather traits in an introduced parrot species, and suggest that these condition‐dependent and/or sexually dichromatic features may serve important intraspecific signaling roles (i.e., mediating rival competitions or mate choices). [ABSTRACT FROM AUTHOR]

The information contained in population genomic data can tell us much about the past ecology and evolution of species. We leveraged detailed phenotypic and genomic data of nearly all living kākāpō to understand the evolution of its feather color polymorphism. The kākāpō is an endangered and culturally significant parrot endemic to Aotearoa New Zealand, and the green and olive feather colorations are present at similar frequencies in the population. The presence of such a neatly balanced color polymorphism is remarkable because the entire population currently numbers less than 250 birds, which means it has been exposed to severe genetic drift. We dissected the color phenotype, demonstrating that the two colors differ in their light reflectance patterns due to differential feather structure. We used quantitative genomics methods to identify two genetic variants whose epistatic interaction can fully explain the species' color phenotype. Our genomic forward simulations show that balancing selection might have been pivotal to establish the polymorphism in the ancestrally large population, and to maintain it during population declines that involved a severe bottleneck. We hypothesize that an extinct apex predator was the likely agent of balancing selection, making the color polymorphism in the kākāpō a "ghost of selection past." The kākāpō is an endangered and culturally significant parrot endemic to Aotearoa New Zealand. This genomic, phenotypic and simulation study of most living kākāpō explores the evolution of green and olive feather coloration, concluding that this polymorphism is likely a remnant of past predation. [ABSTRACT FROM AUTHOR]

Simple Summary: The genetic background of color is a very complex issue in both birds and mammals. Color-related genes may be represented by multiple alleles and show many interactions. Black chicken breeds are special due to their solid uniform pigmentation, which in the case of Ayam Cemani also concerns the bones and skin. One of the crucial genes involved in the melanogenesis pathway is MC1R (melanocortin 1 receptor). It is a one-exon gene that has been already studied in many different species and breeds. In the case of chicken breeds, there are numerous alleles of MC1R and they have a significant impact on the final plumage color of the individual. Here, the Ayam Cemani MC1R complete coding sequence is characterized for the first time. A new MC1R missense substitution has enabled us to distinguish a new haplotype/extended black allele. This is important in terms of completing and supporting current knowledge concerning the genetic background of plumage control, as well as in relation to describing genetic diversity between different breeds. Plumage color is one of the most important traits characterizing chicken breeds. Black-boned chickens constitute a specific group of breeds with a unique phenotype. One of the representatives is the Indonesian Ayam Cemani. The extraordinary black phenotype results from a specific chromosomal rearrangement. We used complete CDS of crucial color-related gene MC1R, which plays a key role in melanin distribution but has not been previously studied in Ayam Cemani. It turned out that Ayam Cemani individuals possess a newly found non-synonymous mutation G355A resulting in amino acid substitution D119N. Together with the presence of G274A (E92K), the new missense variant enabled us to distinguish a new extended black allele at the E locus. All of the investigated birds were heterozygous in terms of the new mutation. Previous studies and our own results indicate a high level of genetic variation within the MC1R gene within and between chicken breeds. Besides the key mutations that make it possible to distinguish particular major alleles, there are also numerous substitutions that give haplotypes more characteristics for individual breeds. [ABSTRACT FROM AUTHOR]

Plumage pigmentation and ornamentation can indicate male phenotypic quality in many avian species and represent traits that are often selected for by females. Melanins are some of the most widespread classes of pigments in the animal kingdom and form the many shades of black and brown feather colors across raptor taxa. Eumelanin is responsible for the darker shades of black and brown, whereas pheomelanin is responsible for the lighter brown shades and rusty red coloration that are found in many buteonine raptors, including Swainson's Hawks (Buteo swainsoni). Plumage polymorphism has been examined in various raptor species along with morphometric differences as a basis for sexual dimorphism; however, the potential for sexual dimorphism in the form of pheomelanin-pigmented plumage has rarely been discussed. We examined this phenomenon in Swainson's Hawks by digitally sampling breast feathers from adult museum specimens, and we utilized an imaging toolbox for multispectral image analysis in the open-source ImageJ software to compare red pixel values between sexes. We found a significant difference in normalized red pixel value means between male and female birds, with higher redness values strongly correlating with male individuals, regardless of morph type. This indicates a relationship between pheomelanin pigmentation and sex, illustrating a basis for sexual dimorphism within the species, as well as the potential for sexual selection of redder males. [ABSTRACT FROM AUTHOR]

In numerous animals, dramatic coloration (e.g. bright red or yellow) often indicates potential fitness, but it is less clear whether subtle coloration in the same individuals (e.g. grey or brown) could also encode such signals. To determine if subtle coloration could indicate health in a bird species with colorful feathers, house finches (Haemorhous mexicanus), we used spectrometry to objectively quantify leg brightness and saturation before, six days after, and 13 days after captive individuals were inoculated with a naturally‐occurring bacterial pathogen, Mycoplasma gallisepticum. We found that legs became less bright six days after infection (near the typical peak of infection), then more bright and less saturated at 13 days (entering the typical recovery period). These results suggest that subtle colors could reliably indicate current infection status, and therefore survival potential. [ABSTRACT FROM AUTHOR]

Crypsis is a common strategy used by animals to avoid detection. In many bird taxa, plumage colour patterns are assumed to play a role in crypsis, but few studies have directly measured plumage crypsis on ecologically relevant substrates from the perspective of relevant signal receivers. To address this gap, we tested whether the plumage colour patterns of three North American woodpeckers commonly found in New Jersey (U.S.A.) are more cryptic to avian predators on trees utilized for foraging than a random subset of trees from their habitat. We focused on the red-bellied woodpecker, Melanerpes carolinus , downy woodpecker, Dryobates pubescens , and hairy woodpecker, Leuconotopicus villosus. First, we took standardized photographs of the bark of trees on which we observed woodpeckers foraging, as well as photographs of the bark of trees from transects in the same area. Next, we superimposed standardized photographs of woodpecker specimens (dorsal view) onto the bark samples and adjusted the resulting images to estimate how they would appear to the visual system of an avian predator. We then estimated four types of achromatic crypsis from each bird/bark combination image: granularity matching, contrast matching, luminance matching and disruptive coloration. We also estimated how well woodpeckers matched the bark substrates in terms of colour by quantifying the degree of colour similarity in a colour space representing a typical avian predator. We found that woodpeckers were more cryptic against trees they utilized for foraging in terms of disruptive coloration, luminance matching and colour matching, suggesting that the need to be cryptic while foraging is likely to have shaped the evolution of woodpecker plumage patterning. • We tested degree of crypsis of woodpecker plumage on foraging and nonforaging trees. • All three woodpecker species tested were more cryptic on foraging trees. • Crypsis strategies included disruptive coloration, luminance matching and colour matching. • Woodpecker species showed some degree of crypsis specialization. • Avian predator visual acuity influences effectiveness of woodpecker crypsis. [ABSTRACT FROM AUTHOR]

Sexual signals such as colour ornamentation and birdsong evolve independently of each other in some clades, and in others they evolve positively or negatively correlated. We rarely know why correlated evolution does or does not occur. Here, we show positively correlated evolution between plumage colour and song motor performance among canaries, goldfinches and allies, associated with species differences in body size. When controlling for body size, the pattern of correlated evolution between song performance and colour disappeared. Syllable diversity was not as strongly associated with size, and did not evolve in a correlated manner with colour. We argue that correlated evolution between song and colour was mediated by large size limiting song motor performance, likely due to constraints on the speed of moving heavier bills, and by larger species having less saturated plumage colour, possibly due to life-history traits of larger birds (e.g. longevity, stable pairs) contributing to weaker sexual selection. Results are consistent with the hypothesis that correlated evolution between sexual signals is influenced by how, in a clade, selective pressures and constraints affecting each type of signal happen to be co-distributed across species. Such contingency helps explain the diversity in clade-specific patterns of correlated evolution between sexual signals. [ABSTRACT FROM AUTHOR]

Introduction: Indigenous chickens are very important to households for income and protein. However, their performance is usually poor, especially under small-scale farmer management, despite their potential to perform better. The performance of these chickens can be improved by selective breeding. However, for this to be a success, there is a need to understand the phenotypic and production characteristics of these chickens fully. Hence, this study aimed to characterize the phenotypes of these chickens and their production system among small-scale farmers. Method: A structured questionnaire was administered to 177 small-scale farmers. A total of 538 chickens whose mean weight was 1.66 kg were individually phenotyped in Luapula, Muchinga, and Northern provinces of Zambia. Results: Ownership of the indigenous chickens was dominated by females (65.37%), with most (64.31%) having attained primary education. Most housed their chickens in family houses (42.03%). All the farmers let their chickens scavenge for their feed, with 45.58% of them providing basic supplementation. Most (84.10%) farmers bought their breed stock from within their community and had a mean flock size of 12.5 chickens/household, which they mostly (78.09%) kept as free-range. The majority (77.39%) practiced culling, with low productivity being the most common reason for culling (84.45%). Only 59.01% of farmers practiced selective breeding, while 86.22% practiced uncontrolled mating. The age at first mating for cocks and hens was 6.8 months and 6.34 months, respectively, with 6.73 months being the age at first egg. It takes 15.43 days to reach a mean clutch size of 13 eggs. The hatchability and mortality at 8 weeks were 83.44% and 67.57%, respectively. All chickens were sold as live chickens, and the majority (51.59%) of the farmers sold their chickens within the community at 7.23 months. Diseases and predators were the most common challenges affecting farmers in the study area. Consultations with veterinarians, vaccinations, and deworming were uncommon while treating sick chickens mostly using ethnoveterinary medicines was common. The most common qualitative traits were brown (27.88%) and mixed (26.77%) plumage color, white skins (91.45%) and shanks (48.70%), single comb type (91.08%), red earlobe (55.76%), and orange eyes (78.07%). All linear body measurements positively and significantly correlated with the body weight averaging 1.66kgs, an indicator that selection for any of them would result in a corresponding increase in body weight. Principal Component Analysis extracted two components with 69.38% of the total variation. Discussion: The diversity in phenotypes of these chickens and their production systems indicate huge potential for improvement by implementing breeding programs. [ABSTRACT FROM AUTHOR]

Many animals display numerous colors that can range from red, green, blue, and orange to ultraviolet, whereas others are dull or have a uniform coloration. The reason for this variation in coloration remains unknown. It has been hypothesized that different colors represent multiple signals that either reflect different components, redundant information, or simply no longer provide reliable information regarding body quality. Here, we analyzed the highly diverse coloration of male golden pheasants (Chrysolophus pictus) using an avian visual model from the avian visual system and related the different components of coloration to several phenotypic traits of body quality. We found that different components of plumage color correlated with the length of the body, tail, spur, and beak, suggesting that the multiple colors in male golden pheasants signal different components of body quality. In particular, tail length was correlated with many aspects of coloration, especially the green and orange colors of neck plumage, which are particularly important because male golden pheasants spread their neck plumage and show it to females during their courtship display. Therefore, these findings reveal that the plumage colors of male golden pheasants encode multiple signals that reflect their body condition during courtship displays. [ABSTRACT FROM AUTHOR]

Brilliant, diverse colour ornaments of birds were one of the crucial cues that led Darwin to the idea of sexual selection. Although avian colouration plays many functions, including concealment, thermoregulation, or advertisement as a distasteful prey, a quality‐signalling role in sexual selection has attracted most research attention. Sexually selected ornaments are thought to be more susceptible to external stressors than naturally selected traits, and as such, they might be used as a test for environmental quality. For this reason, the last two decades have seen numerous studies on the impact of anthropogenic pollution on the expression of various avian colour traits. Herein, we provide the first meta‐analytical summary of these results and examine whether there is an interaction between the mechanism of colour production (carotenoid‐based, melanin‐based and structural) and the type of anthropogenic factor (categorised as heavy metals, persistent organic pollutants, urbanisation, or other). Following the assumption of heightened condition dependence of ornaments under sexual selection, we also expected the magnitude of effect sizes to be higher in males. The overall effect size was close to significance and negative, supporting a general detrimental impact of anthropogenic pollutants on avian colouration. In contrast to expectations, there was no interaction between pollution types and colour‐producing mechanisms. Yet there were significant differences in sensitivity between colour‐producing mechanisms, with carotenoid‐based colouration being the most affected by anthropogenic environmental disturbances. Moreover, we observed no significant tendency towards heightened sensitivity in males. We identified a publication gap on structural colouration, which, compared to pigment‐based colouration, remains markedly understudied and should thus be prioritised in future research. Finally, we call for the unification of methods used in colour quantification in ecological research to ensure comparability of results among studies. [ABSTRACT FROM AUTHOR]

Aim Location Time Period Major Taxa Studied Methods Results Main Conclusions Understanding the ecological determinants of interspecific achromatic (light‐to‐dark) plumage variation in birds is crucial yet challenging due to the complex interplay of climatic, habitat‐related, and morphological influences. This study aimed to disentangle the effects of temperature, precipitation, habitat openness, body mass and hand‐wing index (HWI, a widely used single‐parameter proxy for the extent to which a species relies on flight) on shaping achromatic plumage variation among bird species.Global.Contemporary.Birds.Based on data from over 8000 sessile bird species globally, we employed phylogenetic linear regressions to account for achromatic plumage colour in relation to temperature, precipitation, habitat openness, body mass and HWI, while correcting for phylogenetic non‐independence between species. Furthermore, we conducted phylogenetic path analyses to decompose direct from indirect effects.We found that temperature, precipitation, habitat openness and body mass exerted separate but interactive effects on the variation in achromatic colour across species. Species inhabiting cold, wet or densely vegetated environments were darker coloured, while smaller species were lighter. Darker plumage was more strongly related to higher precipitation in colder regions for nocturnal species. For diurnal species, darker plumage was more closely associated with higher precipitation in more open habitats, whereas lighter plumage was more linked to lower mass in denser habitats. Noteworthy was the identification of a substantial correlation between achromatic colour and HWI. Diurnal species that are more aerial were lighter. Conversely, nocturnal flyers, especially females, tended to be darker.The findings highlight the multifaceted nature of plumage coloration evolution, with adaptations for thermal efficiency, crypsis, signalling, waterproofing or protection against bacteria. However, the variable relative importance of these factors among groups emphasizes the significance of each factor in different contexts. [ABSTRACT FROM AUTHOR]

Color aberrations in birds corresponds with important ecological functions, including thermoregulation and physiological impacts, camouflage and increased predation, and social interactions with conspecifics. Color aberrations in birds have been reported frequently in the scientific literature, but aberrations in many species remain undocumented or understudied. We investigated records of leucism in malachite kingfishers (Corythornis cristatus) from observations of community scientists on iNaturalist and eBird in Uganda. Leucistic kingfishers were only observed within the Queen Elizabeth National Park (QENP), Uganda. When considering all observations of malachite kingfishers that included photographs within the QENP, leucistic individuals accounted for 13.0% and 10.4% of total malachite kingfisher observations within the study area from iNaturalist and eBird, respectively. Leucistic observations were recorded from September 2015 through February 2017, making up 60.0% and 68.2% of observations of malachite kingfishers within the study area from iNaturalist and eBird during that time, respectively. The localized and short documentation period suggests observations represent a single individual, while the high observation rate likely corresponds with collection bias due to the novelty of the individual. Our findings help to better understand the ecological importance and potential consequences for color‐aberrant individuals, although color aberration did not appear to inhibit our subject's ability to find a mate. Our work also highlights how participatory science can promote the documentation of color‐aberrant individuals in wild populations, although it poses challenges when trying to estimate abundance. [ABSTRACT FROM AUTHOR]

Feathers are structures unique to birds that serve important functions such as flight, thermoregulation, and communication. Bacteria that live on the feathers, particularly ones that can break down keratin, have the potential to damage feathers and disrupt their use in communication. We predicted that birds could behaviorally manage their feather bacterial abundances by preening their feathers. We also predicted that individuals with lower feather bacterial abundances would have brighter and more colorful feathers. To test these predictions, we measured the amount of time individuals in a colony of captive Indian peafowl Pavo cristatus spent preening their feathers. We also collected feathers to determine bacteria abundance on the feather surface and to measure feather coloration. We found that birds had lower feather bacteria levels when they spent more time preening their own feathers, but only in female birds. We also found that bacteria abundances were not correlated with any feather color variables we measured. These results suggest that birds can manage feather bacterial abundances by preening but feather bacteria may not influence feather coloration in this species. [ABSTRACT FROM AUTHOR]

In most bird species, males are more ornamented and compete for females, who contribute more to offspring care. In a minority of species, this pattern is reversed, with more colorful females competing for mates and males taking care of parental duties. In such sex-role reversed species, the links between colorful ornamentation, individual quality and mating success are not well established. Phalaropus fulicarius (Red Phalarope) is a colorful sex-role reversed migratory shorebird with regular social polyandry, in which both sexes show considerable color variation. Here, we describe sex differences in color and quantify associations between color variation and indicators of quality and mating success in both sexes. Using a large sample of photos collected across 3 consecutive years on the Arctic breeding grounds, we scored color variation for 4 body parts (bill, crown, cheek, and breast), and analyzed scores separately and combined into an overall color score. Females were more colorful and larger than males, and individuals could be unambiguously sexed by crown color. Nevertheless, there was substantial variation within sexes and some overlap between males and females in bill, cheek, breast, and overall color scores. Assortative mating by color was only found for the bill. Color variation did not correlate with plasma testosterone levels, except for male cheek color. Females in better body condition had yellower bills and higher overall color scores, while early-arriving birds had higher breast and overall scores. Phalaropus fulicarius that bred locally were heavier than those that did not, but they did not have higher color scores. Female color variation did not predict the probability of local social polyandry nor variation in clutch size, and male coloration did not predict the probability of nest predation. In conclusion, P. fulicarius color variation showed modest correlations with individual quality and was unrelated to variation in local reproductive success. [ABSTRACT FROM AUTHOR]

The red-crested cardinal (Paroaria coronata) is an emblematic bird of the southern cone of South America that has been traditionally classified as sexually monomorphic and monochromatic from a human visual perspective. Using reflectance spectrometry, we analyzed sexual differences in the coloration of the red head plumage patch of adult wild red-crested cardinals in central-eastern Argentina. We also described sexual differences in body size and determined the onset of morphometric differences by comparing morphological measurements and growth rate between male and female nestlings. Adult males had on average longer wings and brighter red plumage relative to females. Similar to adults, nestlings were sexually dimorphic at fledging and presented sex-specific growth curves. Male nestlings grew faster and reached a larger size at the fledging time. Both for adults and nestlings, wing length was the trait that expressed sexual differences in body size. Our results are consistent with recent studies in passerines indicating that many birds considered sexually monochromatic are likely dichromatic when considering avian visual capacities. This study allows the red-crested cardinal to be re-categorized as sexually dimorphic and dichromatic. [ABSTRACT FROM AUTHOR]

In laying hen husbandry, severe feather pecking and cannibalism are multifactorial problems. Solving these problems is a matter of urgency, as beak trimming is banned in several European countries, including Germany. One approach to addressing severe feather pecking and cannibalism is the administration of additional enrichment material to support normal behaviour. In this on‐farm study, two flocks of 17,500 Lohmann Brown‐Lite laying hens each were evaluated during one production period (18–78 weeks of life, WoL). One flock was provided with alfalfa bales and pecking stones in combination (EnGr), whereas the other flock served as a control without additional enrichment material (CoGr). During production, the flocks were visited at regular intervals. On each visit, a sample of 50 hens per flock were weighed and scored for plumage condition and skin lesions. The mortality rate was recorded daily by the farm staff. No significant difference in plumage condition and mortality rate was found between EnGr and CoGr (p >.05, Mann‐Whitney U test). As there were hardly any skin lesions in both groups during the study period, the effect of additional enrichment material on this variable could not be determined. The average body weight of the EnGr was significantly higher than the average body weight of the CoGr on numerous examination days (26 WoL, p <.001; 34 WoL, p =.040; 42 WoL, p =.007; 62 WoL, p =.041; 66 WoL, p =.006; 74 WoL, p =.036; 78 WoL, p =.028, t‐tests). However, this effect could not be clearly attributed to the administering of additional enrichment material, as the feeding and performance variables for EnGr and CoGr had been recorded together because of the housing for the two flocks being supplied by one silo and water source, and eggs from the flocks being collected altogether. [ABSTRACT FROM AUTHOR]

Animals often moderate behaviours based on environmental and social cues to enhance their chances of survival and reproductive success. This requires reliable cues that reflect changes in ambient conditions. Environmental pollutants can increase communication costs and distort the accuracy of received information, leading to negative effects on the outcome of behavioural adjustments. Consequently, selection may reduce behavioural plasticity to avoid errors or promote more prudent decision making when certain cues become unreliable. In aquatic ecosystems, water turbidity shows high levels of natural variation, but human activities amplify its magnitude and extent by increasing algae and suspended solids in the water. Here, we investigated how elevated levels of water turbidity affected mating decisions made by female guppies in a laboratory setting. Guppies are a widespread species with a broad tolerance of polluted environments, and females rely heavily on visual cues when making mate choice decisions. We manipulated turbidity by adding suspended solids to water and tested how this affected female preference for males with more orange coloration. We found that females spent more time near males with a greater area of orange coloration in low turbidity water, but that this preference disappeared in both the mid and high turbidity water treatments. Moreover, female preferences were repeatable in low turbidity water and high turbidity water but not in mid turbidity water. Together, our results suggest that water turbidity impairs the ability of females to discern male coloration and affects the consistency of mate preferences. This could have consequences for the evolution of male coloration in turbid waters. • Male guppies have vibrant colour patterns indicating quality. • We investigated how water turbidity affects mating decisions by female guppies. • Females preferred to associate with more colourful males in low turbidity water. • Increased turbidity resulted in no preference for more colourful males. • Female mate preference was not repeatable in mid turbidity water. [ABSTRACT FROM AUTHOR]

Copyright of Veterinarska Stanica is the property of Croatian Veterinary Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Psittacofulvins are polyenal dyes responsible for coloring parrot feathers and protecting them against photo-oxidation, harmful radicals, and bacterial degradation. To explain the unusual properties of these compounds, the thermodynamic and global chemical activity descriptors characterizing four natural and three synthetic psittacofulvins, as well as their hydroxyl, carboxyl and dialdehyde derivatives, were determined. To this aim, the DFT method at the B3LYP/QZVP theory level and the C-PCM solvation model were used. The calculations enabled the selection of the projected compounds for the greatest bioactivity and potential applicability as multifunctional ingredients in medicines, cosmetics, supplements, and food, in which they may play a triple role as preservative, radical scavenger, and coloring agent. The results obtained provide arguments for the identification of a fifth psittacofulvin within the parrot feather pigment, characterized by ten conjugated double bonds (docosadecaenal). [ABSTRACT FROM AUTHOR]

Simple Summary: A lot of avian species are morphologically monomorphic, and thus, sex determination is difficult if it is based only on their external examination. Molecular sex identification has become a crucial tool in various fields of biology, including ornithology. This non-invasive method used to determine the genetic sex of birds of any age, in our case, Eudromia elegans (Paleognathae, Tinamiformes), can proceed with regard to the differences between avian male (ZZ) and female (ZW) chromosomes. According to our experience, the other molecular methods failed in the sex determination of this exact species. The new test was designed to be reliable, fast, and simple to determine the sex of the individuals of E. elegans. Molecular sexing has significant implications for understanding various aspects of its biology, including mating systems, population genetics, and conservation strategies. By accurately determining the sex of individuals within a population, researchers can investigate sex ratio patterns, reproductive success, and gene flow. Sex determination based just on morphological traits such as plumage dichromatism, sexual size dimorphism, behavior, or vocalizations is really challenging because of the sexual monomorphism present in more than half of avian species. Currently, a lot of them can be tested through DNA-based procedures, but they do not fit all the avian species, such as Eudromia elegans. The aim of this study was to design a new molecular method suitable for routine sex determination for that species that is fast, simple, and cost- and time- effective. DNA was isolated from dry blood stain and/or chest feather samples of E. elegans species. We used two sets of sex-specific primers (ZF/ZR and WF/WR) to amplify the expected fragments localized on the highly conserved CHD1 gene to distinguish between sexes due to the W-specific DNA sequence present only in females. We confirmed the accuracy and consistency of the PCR-based method based on length differences to distinguish between the sexes of E. elegans, which amplified two fragments in females and one fragment in males. [ABSTRACT FROM AUTHOR]

Carotenoids are naturally occurring pigments in plants, algae, fungi, insects, and crustaceans. Krill and prawns contain high levels of some value-added nutrients for the aquaculture industry, such as astaxanthin which is used as a colouring agent. In birds with ornamental plumage, such as canaries, the carotenoid-pigmented plumage and red hues are exclusively due to the diet. In this regard, our aim was to study the possibilities of using shrimp waste for feather colouring in canary Serinus canaria domestica. Shrimp Pandalus borealis dried waste was included in the feed of six female red lipochrome mosaic canaries Serinus canaria domestica for three months during their third molt. The basic diet consisted of a seed mixture (canary seed, sunflower seed without shell, linseed, and rapeseed), rearing food (Quiko®Bianco), and conditioning food (Quiko®Rusk) with the supplementation of an oil suspension of dried shrimp waste (3%). The ad libitum-fed birds had additional free access to pasta (Legazin® Procria White Morbida). To evaluate the effect of shrimp waste on feather colouring, covert feathers were taken from the tail in the region of the uropygial gland. Diffuse reflectance spectroscopy of the most intensely coloured parts of the feathers was measured by a spectrophotometer. The chromaticity coordinates in a CIE xyY colour space were calculated from the measured spectroscopy. The results of the experiment showed that shrimp waste increased chromaticity and had no negative effect on the canaries. On this basis, the authors assumed that dried shrimp waste could be an alternative to synthetic dyes. [ABSTRACT FROM AUTHOR]

Colour aberrations are rare conditions in birds that are caused by genetic as well as environmental factors. Among the colour aberrations in birds, albino, leucism, progressive greying, brown, dilution, ino, and melanism are the best known. This report describes an observation of colour aberration in a Spotted Dove (Spilopelia chinensis suratensis) from India. It was recorded in the Deobali Jalah (an IBA site) of Nagaon district, Assam. The recorded individual exhibited a pale plumage with normal eyes and some light brown colour in some of the feathers, indicating this to be a form of dilution. The report also represents the first photographic documentation of colour aberration in Spotted Doves from Brahmaputra Valley of Assam, India. Further research is necessary to comprehend the causes of colour aberration in Spotted Doves. [ABSTRACT FROM AUTHOR]

Birds with atypical colours in their plumage are not uncommon however, the potential causes of such aberrations have not been widely examined. Aberrant brownish-rufous phaeomelanin is one type of plumage colour that has been recorded in numerous bird species, including those which essentially contain only eumelanin (black) pigments, including several European woodpeckers. A Middle Spotted Woodpecker Dendrocoptes medius with aberrant phaeomelanised plumage observed in the Bükk Hills, Hungary, is detailed here and an evaluation of the possible nature of this form of plumage discussed. [ABSTRACT FROM AUTHOR]

Animals use colours, morphological structures and behaviour to advertise their dominance status and ability to obtain resources (Resource Holding Potential, RHP) in agonistic contexts with conspecifics. Dominance relationships are also known between species, although the interactions and the information used to assess the other species' RHP remain obscure and empirical evidence of interspecific recognition of status is hard to obtain. Using behavioural inference is particularly important when a species needs to assess the potential loss of fitness in terms of reproduction or survival (e.g., risk of damage or predation) that could be inflicted by another species acting as a predator, parasite or competitor. Our study shows for the first time the existence of interspecific recognition of status signals: Blue tits Cyanistes caeruleus (subordinate species) perceive Great tits Parus major (dominant species) as threats as hole‐nesting competitors, and respond differently based on the size of the great tit's black tie stripe. Blue tits seemed to recognize the meaning of great tits' black ties because they were bolder when defending their nests against small‐tie (less dominant) great tits than when repelling attacks by large‐tie (more dominant) great tit males. Our results stress that behavioural inference can potentially be used to assess the meaning of status signals that presumably evolved in an intraspecific signalling context. [ABSTRACT FROM AUTHOR]

The aim of the present study was to compare the effectiveness of raw chicken feathers (RCFs), NaOH and ethylenediamine-modified chicken feathers (MCFs), and xanthate-modified chicken feathers (XMCFs), treated with both NaOH, ethylenediamine, and carbon disulfide. The physicochemical characteristics of the biosorbents were analyzed using attenuated total reflection Fourier transform infrared spectrophotometry (ATR-FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), adsorption of N2 at −196°C and point of zero charge determination (pHpzc). The biosorption of Cr(VI) using MCFs and XMCFs was evaluated through various parameters, namely, pH, biosorbent amount, and contact time in batch experiments. The results showed a significant increase in the biosorption capacities of MCFs (90.90 mg/g) and XMCFs (100 mg/g) compared to RCFs (52.63 mg/g). The batch adsorption experiments indicated that the optimal conditions for biosorption were pH 2.0, with an equilibrium contact time of 90 min for RCFs, and 60 min for both MCFs and XMCFs. The optimal biosorbent concentrations were 16 g L−1 for RCFs and 12 g L−1 for both MCFs and XMCFs. The biosorption behavior was well described by the Langmuir isotherm and pseudo-second-order kinetic models. The thermodynamic parameters indicated that the biosorption of Cr(VI) onto the biosorbents was a spontaneous and endothermic process. Desorption analysis was carried out using a 0.1 M NaOH solution. [ABSTRACT FROM AUTHOR]

The risk of predation directly affects the physiology, behavior, and fitness of wild birds. Strong social connections with conspecifics could help individuals recover from a stressful experience such as a predation event; however, competitive interactions also have the potential to exacerbate stress. Few studies have investigated the interaction between environmental stressors and the social landscape in wild bird populations. In 2 years of field studies, we experimentally simulated predation attempts on breeding female tree swallows (Tachicyneta bicolor). At the same time, we manipulated female breast plumage color, a key social signal. Simulated predation events on tree swallows early in the nestling period reduced young nestlings' mass by approximately 20% and shortened telomere lengths. Ultimately, only 31% of nestlings in the predation group fledged compared with 70% of control nestlings. However, the effects of experimental manipulations were timing dependent: the following year when we swapped the order of the experimental manipulations and simulated predation during incubation, there were no significant effects of predation on nestling condition or fledging success. Contrary to our expectations, manipulation of the social environment did not affect the response of tree swallows to simulated predation. However, manipulating female plumage during the nestling period did reduce nestling skeletal size and mass, although the effects depended on original plumage brightness. Our data demonstrate that transient stressors on female birds can have carry‐over effects on their nestlings if they occur during critical periods in the breeding season. [ABSTRACT FROM AUTHOR]

The preference for colours has profound impacts on the fitness of visually oriented species, influencing the search for food resources and mates of better quality while also modulating various physiological and behavioural features. Such processes may be more important to sexually dimorphic species, especially coloured ones since visual signals play an important role in intra- and intersexual communication. Amazon small streams vary widely regarding the amount of dissolved organic carbon resulting in black (red-biased) and clear (mostly transparent) water types. The sailfin tetra Crenuchus spilurus is a small sexually dimorphic species composed of two main genetic lineages that live in black and clear water types. Recently, we have shown that the female sexual preference for male ornaments colouration differs between individuals inhabiting black and clear water types. Females from black waters do not choose males primarily based on colouration under strongly red-biased lighting, but females from clear waters do, which suggests that the importance of red colours for sexual behaviour differs between lineages of the sailfin tetra. Here, we evaluated the sailfin tetra female environmental colour preference through the choice between a red and a full spectrum illuminated environments. Females from black waters and clear waters preferred red-lightened environments. Such results suggest that the females are attracted to the red colouration outside the context of mating, irrespective of the prevailing lighting condition of their native environment. This preference for red illuminated environments may be important for several processes, including physiological and behavioural features. [ABSTRACT FROM AUTHOR]

Many biological studies rely on accurate sex determination of individuals to investigate sex-specific differences in wild populations. Numerous species can be reliably sexed in the field using external characteristics such as plumage color and ornamentation or in the hand using breeding characteristics such as a brood patch (female) or cloacal protuberance (male). However, plumage differences may not be present year-round and breeding characteristics are not present outside of the breeding season. This is a problem for researchers as they may not be able to reliably sex individuals in the field outside of the breeding season. However, monochromatic species often exhibit sex differences in morphometrics including wing chord length and tarsus length. Recent studies have found that the Eastern (leucophrys) and Puget Sound (pugetensis) subspecies of the White-crowned Sparrow (Zonotrichia leucophrys) can be reliably sexed using wing chord length. The Gambel's (gambelii) subspecies was last studied in 1985 and the Nuttall's (nuttalli) subspecies has not been tested. We combined wing chord length, tarsus length, and sex data from adult Gambel's and Nuttall's White-crowned Sparrows to determine if these subspecies could be reliably sexed using wing chord length and/or tarsus length. We also determined if the migratory Gambel's subspecies and resident Nuttall's subspecies varied morphologically. We found that the Gambel's and Nuttall's subspecies could be reliably sexed using wing chord length outside overlapping ranges of 74–78 and 69–77 mm, respectively. We also found that the Gambel's subspecies had longer wing chord lengths and shorter tarsus lengths than the Nuttall's subspecies. Our findings provide a useful tool for sex determination in Gambel's, but not Nuttall's, White-crowned Sparrows. Further, our findings show that migratory and resident individuals within the same species vary morphologically, which may relate to the different selective pressures they face. [ABSTRACT FROM AUTHOR]

Simple Summary: Shitou geese are the exclusive representative of a large-sized goose breed in China, typically exhibiting gray feathers but also possessing a recessive white plumage. However, the precise mechanism underlying the formation of this white plumage coloration in Shitou geese remains unclear. Here, a transcriptome sequencing analysis was conducted to identify candidate genes and microRNAs (miRNAs) that may be associated with the white plumage color in Shitou geese. A number of pigmentation genes and miRNAs were identified as candidates that may regulate white plumage color formation in Shitou geese. This result may be important for understanding the genetic mechanism underlying the formation of white plumage color in Shitou geese. The Shitou goose, a highly recognized indigenous breed with gray plumage originating from Chaozhou Raoping in Guangdong Province, China, is renowned for being the largest goose species in the country. Notably, during the pure breeding process of Shitou geese, approximately 2% of the offspring in each generation unexpectedly exhibited white plumage. To better understand the mechanisms underlying white plumage color formation in Shitou geese, we conducted a comparative transcriptome analysis between white and gray feather follicles, aiming to identify key genes and microRNAs that potentially regulate white plumage coloration in this unique goose breed. Our results revealed a number of pigmentation genes, encompassing TYR, TYRP1, EDNRB2, MLANA, SOX10, SLC45A2, GPR143, TRPM1, OCA2, ASIP, KIT, and SLC24A5, which were significantly down-regulated in the white feather follicles of Shitou geese. Among these genes, EDNRB2 and KIT emerged as the most promising candidate genes for white plumage coloration in Shitou geese. Additionally, our analysis also uncovered 46 differentially expressed miRNAs. Of these, miR-144-y may play crucial roles in the regulation of feather pigmentation. Furthermore, the expression of novel-m0086-5p, miR-489-y, miR-223-x, miR-7565-z, and miR-3535-z exhibits a significant negative correlation with the expression of pigmentation genes including TYRP1, EDNRB2, MLANA, SOX10, TRPM1, and KIT, suggesting these miRNAs may indirectly regulate the expression of these genes, thereby influencing feather color. Our findings provide valuable insights into the genetic mechanisms underlying white plumage coloration in Shitou geese and contribute to the broader understanding of avian genetics and coloration research. [ABSTRACT FROM AUTHOR]

Sex-limited polymorphism has evolved in many species including our own. Yet, we lack a detailed understanding of the underlying genetic variation and evolutionary processes at work. The brood parasitic common cuckoo (Cuculus canorus) is a prime example of female-limited color polymorphism, where adult males are monochromatic gray and females exhibit either gray or rufous plumage. This polymorphism has been hypothesized to be governed by negative frequency-dependent selection whereby the rarer female morph is protected against harassment by males or from mobbing by parasitized host species. Here, we show that female plumage dichromatism maps to the female-restricted genome. We further demonstrate that, consistent with balancing selection, ancestry of the rufous phenotype is shared with the likewise female dichromatic sister species, the oriental cuckoo (Cuculus optatus). This study shows that sex-specific polymorphism in trait variation can be resolved by genetic variation residing on a sex-limited chromosome and be maintained across species boundaries. [ABSTRACT FROM AUTHOR]

Background: Poultry feather waste has a potential for bioenergy production because of its high protein content. This research explored the use of chicken feather hydrolysate for methane and hydrogen production via anaerobic digestion and bioelectrochemical systems, respectively. Solid state fermentation of chicken waste was conducted using a recombinant strain of Bacillus subtilis DB100 (p5.2). Results: In the anaerobic digestion, feather hydrolysate produced maximally 0.67 Nm3 CH4/kg feathers and 0.85 mmol H2/day.L concomitant to COD removal of 86% and 93%, respectively. The bioelectrochemical systems used were microbial fuel and electrolysis cells. In the first using a microbial fuel cell, feather hydrolysate produced electricity with a maximum cell potential of 375 mV and a current of 0.52 mA. In the microbial electrolysis cell, the hydrolysate enhanced the hydrogen production rate to 7.5 mmol/day.L, with a current density of 11.5 A/m2 and a power density of 9.26 W/m2. Conclusions: The data indicated that the sustainable utilization of keratin hydrolysate to produce electricity and biohydrogen via bioelectrical chemical systems is feasible. Keratin hydrolysate can produce electricity and biofuels through an integrated aerobic-anaerobic fermentation system. [ABSTRACT FROM AUTHOR]

Many animals exhibit contrast between their dorsal coloration and their ventral coloration. If selection acts differently on dorsal versus ventral coloration, ancestral covariance between these traits should break down, eventually leading to independent modules of trait evolution. Here, we compare the evolution of feather color across body regions for a clade of Australasian songbirds (Meliphagoidea). We find evidence for three modules of covarying color regions. Among these modules, ventral feathers evolve with high lability, evolving at three times the rate of dorsal plumage and 20 times the rate of flight feathers. While both dorsal plumage and ventral plumage are darker in areas with more precipitation and vegetation, we find that dorsal plumage is twice as similar to colors in satellite photos of background substrates. Overall, differential selection on ventral and dorsal colors likely maintains these as distinct modules over evolutionary timescales—a novel explanation for dorsoventral contrast in pigmentation. [ABSTRACT FROM AUTHOR]

Most of our knowledge of secondary hole-nesting birds comes from populations breeding in human-provided nestboxes, yet these might differ from natural cavities in a number of parameters, including internal dimensions or microclimate, leading to differences in reproductive ecology. Here, we demonstrate differences in plumage coloration, an important visual signal of individual quality, in Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) nestlings raised in natural cavities and nestboxes. For this study, we collected feather samples over two breeding seasons and applied reflectance spectrophotometry to calculate color metrics. Carotenoid chroma was higher in nestbox-reared Blue Tits, whereas brightness was higher in nestbox-reared Great Tits (with a similar tendency for Blue Tits). The latter result might be explained by the better nutritional condition of Great Tit nestlings raised in nestboxes. Furthermore, we found no evidence for preference of adults expressing more elaborate plumage towards a specific cavity type in either species. Consequently, we assume that differences in nestling plumage reported here are driven by rearing conditions (nestboxes vs. natural cavities) and not by differences in plumage-based parental quality. Our study adds to the growing body of evidence confirming that anthropogenic environmental modifiers, such as nestboxes, might influence avian physiology and the resulting phenotype. [ABSTRACT FROM AUTHOR]

Carotenoid-based ornamentation can vary greatly among individual birds of the same population. This variability might consider the timing and duration of moult. Crossbills (genus Loxia) show large variation in their colour patterns, ranging from dull yellow to red. Thus, they provide an excellent avian model for testing whether the timing and duration of their moult are associated with their dominant colour patterns. Using a dataset of more than 1900 crossbills captured in the Pyrenees (Spain), we observed that individuals with red feathers started their primary moult early, while those with yellow feathers started moult on an average of 18 days later. We also found that yellow crossbills were more likely to suspend moults (i.e. temporally interrupt moult), postponing a part of the moult until September. These differences in the moulting process may be related to plumage colour, which reflect individual condition. [ABSTRACT FROM AUTHOR]

Plumage ornaments of birds, both pigment-based and structural, are considered age or condition-dependent, honestly signalling male quality, sexually selected traits, influencing the variation in breeding performance as well as adaptive sex allocation. In the present study, we examine the effect of age of males on the plumage structural colour in Common Kingfisher, and evaluate the breeding output (laying date, total number of young per breeding season, mean number of young per nest, total number of broods) and sex ratio in relation to two ornamental traits (forehead and rump structural colour). During the three years 2016–2018 in the Danube river system (south-western Slovakia), we collected data from 49 males, 102 broods and 645 nestlings. Our data demonstrate that structural colour is a condition-related and age-sensitive signal, while males with increased weight expressed less saturated blue forehead feathers, and old males displayed more saturated cyan rump feathers than young ones. Moreover, the brood sex ratio varies with male coloration in an age-dependent manner. The plumage colour of young males did not affect the brood sex ratio, whereas old males with increasing intensity of cyan rump had more sons than duller ones. Neither single ornamental trait nor age predicted breeding output of kingfisher males. Nevertheless, our results indicate that the blue structural plumage of kingfisher males may serve as an indicator of age and a certain kind of quality with a consequence on adaptive sex allocation in this species. [ABSTRACT FROM AUTHOR]

Evolutionary radiations provide important insights into species diversification, which is especially true of adaptive radiations. New World wood warblers (Parulidae) are a family of small, insectivorous, forest-dwelling passerine birds, often considered an exemplar of adaptive radiation due to their rapid diversification followed by a slowdown. However, they deviate from the expectations of an adaptive radiation scenario due to the lack of conspicuous morphological and ecological differentiation. We fitted several macroevolutionary models to trait data in 105 species of wood warblers. We tested whether morphological traits underwent an early burst of evolution (suggesting adaptation to new ecological niches in adaptive radiations) and whether song and colour underwent a diversity-dependent acceleration of trait evolutionary rate (consistent with reproductive interference driving signal evolution). Morphology and song evolved gradually under stabilizing selection, suggesting niche conservatism, with morphology possibly acting as a constraint on song evolution. In contrast, many feather colour traits underwent a diversity-dependent burst of evolution occurring late in the clade's history. We suggest that a two-step process has led to the remarkable diversification of wood warblers. First, their early diversification probably proceeded by allopatric speciation. Second, feather colour divergence likely occurred during secondary contact after range expansion. This diversification of signalling traits might have facilitated species coexistence, in combination with behavioural niche partitioning. Wood warblers seem to present characteristics of both adaptive and non-adaptive radiations. [ABSTRACT FROM AUTHOR]

Female cichlid fish living in African great lakes are known to have sensory systems that are adapted to ambient light environments. These sensory system adaptations are hypothesized to have influenced the evolution of the diverse male nuptial coloration. In rock-dwelling Lake Malawi mbuna cichlids, however, the extent to which ambient light environments influence female sensory systems and potentially associated male nuptial coloration remains unknown. Yet, the ubiquitous blue flank coloration and UV reflection of male mbuna cichlids suggest the potential impacts of the blue-shifted ambient light environment on these cichlid's visual perception and male nuptial coloration in the shallow water depth in Lake Malawi. In the present study, we explored whether and how the sensory bias of females influences intersexual communication in the mbuna cichlid, Metriaclima zebra. A series of choice experiments in various light environments showed that M. zebra females 1) have a preference for the blue-shifted light environment, 2) prefer to interact with males in blue-shifted light environments, 3) do not show a preference between dominant and subordinate males in full-spectrum, long-wavelength filtered, and short-wavelength filtered light environments, and 4) show a "reversed" preference for subordinate males in the UV-filtered light environment. These results suggest that the visual perception of M. zebra females may be biased to the ambient light spectra in their natural habitat by local adaptation and that this sensory bias may influence the evolution of blue and UV reflective patterns in male nuptial coloration. [ABSTRACT FROM AUTHOR]

Species are the basic units in evolution and biodiversity and thus a reasonable species classification is essential to assess and protect biodiversity. The classifications of the Naumann's and dusky thrush complexes and the red-throated and black-throated thrush complexes are not well defined in Turdidae (Aves, Passeriformes). Herein, we use qualitative and quantitative morphological characters and molecular data to review the taxonomy of these thrush complexes. These four thrushes can be distinguished with qualitative features of feather color and striping. These birds cannot be divided by quantitative features, which only work on two groups of thrush complexes. Phylogenetic analysis based on mitochondrial genes indicate that all haplotypes might be divided into two monophyletic clades corresponding to two groups of thrush complexes. According to coalescence-based species delimitation and the gen-morph species concept, these two groups of thrush complexes should be separated as two distinctive species (T. naumanni and T. ruficollis) and including two subspecies per species. This species classification is also supported by gene flow analysis. There is a significant mixing between these two thrush species in the neighbor-joining (NJ) tree and the cluster analysis using a few microsatellite loci. This leads to a pattern of nuclear-mitochondrial discordance between the two birds that can be explained by several potential mechanisms. This study provides the first comprehensive classification of the two thrush complexes on a population level using morphological and molecular characteristics, which will be useful in expanding our understanding of species division among thrush complexes. [ABSTRACT FROM AUTHOR]

The genetic foundation of chicken body plumage color has been extensively studied. However, little attention has been paid to the inheritance patterns and molecular mechanisms underlying the formation of distal feather colors (tail and wingtip). Differences in these colors are common; for example, the Chinese Huiyang Beard chicken has black tail feathers, but yellow body plumage. Here, the hybrid offspring of Huiyang Beard and White Leghorn chickens were used to study the inheritance patterns of tail‐feather color. The expression levels of pigment genes in differently colored feather follicles were analyzed using quantitative real‐time PCR. The results showed that genetic regulation of tail‐feather color was independent of body‐plumage color. The Dominant White locus inhibited eumelanin synthesis in tail feathers without affecting the formation of yellow body plumage, whereas the Silver locus had the opposite effect. The expression of agouti signaling protein (ASIP) gene class 1 transcripts was significantly lower in black tail‐feather follicles than in yellow body follicles, whereas tyrosinase‐related protein 1 (TYRP1) gene expression was significantly higher in black tail feathers. These differentially expressed genes were confirmed to exert an effect on eumelanin and pheomelanin formation in feathers, thus influencing the regulation of chicken tail‐feather color. In conclusion, this study lays the foundation for further research on the genetic mechanisms of regional differences in feather color, contributing to a better understanding of plumage pigmentation in chickens. [ABSTRACT FROM AUTHOR]

This article provides a list of recently published books and articles on various topics related to Rhode Island history. It covers subjects such as skiing in Rhode Island, the Brown University Band, Rhode Island election tickets, birds of Rhode Island, the Civilian Conservation Corps camps, Newport's Catholics, Puritanism in England and America, and constitutionalism in the American Revolution. The article aims to give library patrons a brief overview of these resources for further research. Additionally, there is an article titled "Timeline of the Formation and Service of the 1st Rhode Island Regiment - Part I" that offers a detailed timeline of the activities and formation of the 1st Rhode Island Regiment from October 1777 to December 1778. It includes an overview essay by the website's creators, a video interview with historian James Oakes, and numerous primary source documents. This resource is particularly valuable for researchers interested in the early years of the American Revolution, with a focus on the experiences of African and Indigenous soldiers. [Extracted from the article]

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. [ABSTRACT FROM AUTHOR]

This article is a review of the book "Audubon as Artist: A New Look at The Birds of America" by Roberta J. M. Olson. The book focuses on the life and artistic accomplishments of John James Audubon, particularly his work on "The Birds of America." The author, an art historian, provides a detailed account of Audubon's early life, his development as an artist, and his interactions with other naturalists and artists. The book includes numerous illustrations of Audubon's bird depictions and compares them to the works of other artists. While the book provides a comprehensive look at Audubon's artistic achievements, it does not discuss his later work on "The Viviparous Quadrupeds of North America" or the controversial aspects of his life, such as his ownership of enslaved people. Overall, the book offers valuable insights into Audubon's art and his impact on subsequent generations of painters. [Extracted from the article]