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Background: Poor feather growth not only affects the appearance of the organism but also decreases the feed efficiency. Methionine (Met) is an essential amino acid required for feather follicle development; yet the exact mechanism involved remains insufficiently understood. Methods: A total of 180 1-day-old broilers were selected and randomly divided into 3 treatments: control group (0.45% Met), Met-deficiency group (0.25% Met), and Met-rescue group (0.45% Met in the pre-trial period and 0.25% Met in the post-trial period). The experimental period lasted for 56 d, with a pre-trial period of 1–28 d and a post-trial period of 29–56 d. In addition, Met-deficiency and Met-rescue models were constructed in feather follicle epidermal stem cell by controlling the supply of Met in the culture medium. Results: Dietary Met-deficiency significantly (P < 0.05) reduced the ADG, ADFI and F/G, and inhibited feather follicle development. Met supplementation significantly (P < 0.05) improved growth performance and the feather growth in broilers. Met-rescue may promote feather growth in broilers by activating the Wnt/β-catenin signaling pathway (GSK-3β, CK1, Axin1, β-catenin, Active β-catenin, TCF4, and Cyclin D1). Compared with Met-deficiency group, Met-rescue significantly (P < 0.05) increased the activity of feather follicle epidermal stem cell and mitochondrial membrane potential, activated Wnt/β-catenin signaling pathway, and decreased the content of reactive oxygen species (P < 0.05). CO-IP confirmed that mitochondrial protein PGAM5 interacted with Axin1, the scaffold protein of the disruption complex of the Wnt/β-catenin signaling pathway, and directly mediated Met regulation of Wnt/β-catenin signaling pathway and feather follicle development. Conclusions: PGAM5 binding to Axin1 mediates the regulation of Wnt/β-catenin signaling pathway, and promotes feather follicle development and feather growth of broiler chickens through Met supplementation. These results provide theoretical support for the improvement of economic value and production efficiency of broiler chickens. [ABSTRACT FROM AUTHOR]

Simple Summary: Skin appendages, such as hair and feathers, are characteristic traits of mammals and birds, respectively. They are prototypes for a much broader range of skin appendages including also scales, claws, scutes and beaks, which develop in land-dwelling vertebrates. All these skin appendages have in common that they consist of dead cells which are tightly packed with specific proteins. This review provides an overview of the protein components of skin appendages characterized so far and identifies gaps of knowledge that need to be addressed by future studies. In particular, keratins and proteins encoded by genes of the so-called epidermal differentiation complex are highlighted as critical contributors to the architecture of feathers, scales and claws. As many skin appendage proteins have been predicted but not fully characterized yet with regard to their three-dimensional structure, interactions with other proteins and distribution in skin cells, they are important topics of ongoing research. Reptiles, birds, mammals and amphibians, together forming the clade tetrapods, have a large diversity of cornified skin appendages, such as scales, feathers, hair and claws. The skin appendages consist of dead epithelial cells that are tightly packed with specific structural proteins. Here, we review the molecular diversity and expression patterns of major types of skin appendage proteins, namely keratin intermediate filament proteins, keratin-associated proteins (KRTAPs) and proteins encoded by genes of the epidermal differentiation complex (EDC), including corneous beta-proteins, also known as beta-keratins. We summarize the current knowledge about the components of skin appendages with a focus on keratins and EDC proteins that have recently been identified in reptiles and birds. We discuss gaps of knowledge and suggest directions of future research. [ABSTRACT FROM AUTHOR]

Bonelli's Eagle is an endangered species with little information on its ectoparasites. We studied their chewing lice (Phthiraptera: Amblycera, Ischnocera) infestations by visually searching the plumage of 64 wild and captive specimens. Three different species were identified: Degeeriella sp., Colpocephalum impressum and Laemobothrion maximum. This is the first case of Laemobothrion maximum on Bonelli's Eagle described. We also observe its haematophagous behavior. Due to the low prevalence of infestations, no alterations in the host health are described. [ABSTRACT FROM AUTHOR]

Simple Summary: A feather-degrading bacterium, Bacillus velezensis PN1, was isolated, and solid-state fermentation conditions were optimized. The resulting fermented feather meal (FFM) was evaluated for bioavailability in broilers. B. velezensis PN1 showed the highest feather degradation rate, with optimal fermentation achieved at 37 °C for 48–72 h. FFM2, produced with 65% moisture at 37 °C for 48 h, was compared with FFM1 (produced at 27 °C) and commercial hydrolyzed feather meal (HFM). FFM2 was found to be more suitable for large-scale production due to its amino acid profile and fermentation efficiency. In a broiler growth trial, diets containing 5% FFM2 showed no significant difference in body weight, feed conversion ratio, or performance efficiency compared to the 5% HFM group (p > 0.05). However, both FFM2 and HFM groups showed lower weight gain than the 5% fish meal (FM) group (p < 0.05). Without supplemental amino acids, growth performance did not differ between FFM2 and HFM groups (p > 0.05). In conclusion, FFM produced by B. velezensis PN1 can completely replace HFM when included at 5% in broiler diets. In this study, an effective feather-degrading bacterium was isolated and the solid-state fermentation condition for feather degradation was optimized. The resulting fermented feather meal (FFM) was evaluated for its bioavailability in broilers. Four Bacillus strains were examined for feather degradation rates, with Bacillus velezensis PN1 exhibiting the highest rate (83.24%, p < 0.05). A 3 × 3 × 3 factorial design was used to test substrate moisture content (45%, 55%, 65%), temperature (27 °C, 37 °C, 47 °C), and incubation time (24, 48, 72 h) for optimized fermentation conditions. In vitro pepsin digestibility (IVPD) revealed a significant interaction between temperature and time (p < 0.05), and the optimal performance was achieved at 37 °C for 72 h, followed by 37 °C for 48 h. Considering production time and cost, FFM2 (produced with 65% moisture at 37 °C for 48 h) was further compared with FFM1 (produced under the same conditions but at a lower temperature of 27 °C), and commercial hydrolyzed feather meal (HFM). IVPD did not differ significantly between FFM1, FFM2, and HFM, as they all showed significantly higher digestibility compared to raw feathers (RFs). FFM1, as well as FFM2, had significantly higher histidine and lysine concentrations than RF (p < 0.05), while FFM2 had a significantly lower cysteine content (p < 0.05). Based on fermentation conditions and amino acid composition, FFM2 was considered more suitable for large-scale production and was used in a broiler growth trial. The inclusion of 5% FFM2 in the broiler diet did not significantly affect body weight at 35 days compared to the 5% HFM group (p > 0.05), although both groups showed significantly lower weight gain than the 5% fish meal (FM) group (p < 0.05). The feed conversion ratio and performance efficiency factor did not differ significantly between the FFM2, HFM, and FM groups (p > 0.05). In groups fed diets without supplemental crystalline amino acids, growth performance did not significantly differ between the HFM and FFM2 groups (p > 0.05), although both performed significantly worse than groups with amino acid supplementation. In conclusion, FFM produced by B. velezensis PN1 through solid-state fermentation enhances feather bioavailability in poultry and can completely replace HFM when included at 5% in broiler diets, offering a potential sustainable alternative for poultry nutrition on a commercial scale. [ABSTRACT FROM AUTHOR]

Feather is a sort of commonly used noninvasive material that can provide DNA and hormones for the research， monitoring and management of birds. However， feather vane is a fully keratinized tissue with very low content of DNA and hormones that often challenges the extraction. In the study， we developed a novel method to co-extract DNA and corticoste⁃ roid from feather vane， named DH-CoEx. The extraction efficiency and usability of DH-CoEx were evaluated by using feath⁃ ers from large feathers represented by the red crowned crane (Grus japonensis) and green peafowl (Pavo muticus) ， and small feathers represented by the chestnut bunting (Emberiza rutila) and little bunting (E. pusilla). The results showed that DH-CoEx could co-extracted total DNA and corticosteroid (cortisol) from feather vanes. The copy number of mitochondrial DNA (mtDNA) extracted from 5 mg feather reached 104 ， that could support amplification of 1，350 bp fragments. The nuclear DNA (nuDNA) could support genotyping of microsatellites with a success rate of 98. 11% - 99. 60% success rate for alleles less than 200 bp. The yield of cortisol co-extracted reach the level of normal single extraction approaches and supportive for physiological analysis. These results suggest that DH-CoEx is a simple and effective method to co-extract DNA and corticosteroids from a fully keratinized feather to support analysis of genetic markers and stress hormone in a broad range of application. [ABSTRACT FROM AUTHOR]

Anthropogenic activities have contributed to the increase of heavy metals and to the alteration of their natural cycles in the environment. Mercury (Hg) is now considered to be one of the most toxic elements whose levels need to be monitored in abiogenic and biogenic environmental compartments. It can enter the body of animal in several ways, mainly through contaminated food. In this study, we compared mercury levels in mouse hair and songbird feathers from Zhongar Alatau National Park in Kazakhstan and from national parks in Slovakia. We sampled mice of the genus Apodemus and songbirds of three genera – Parus, Phylloscopus and Turdus. Total mercury concentrations were measured using DMA-80. The results showed higher levels of Hg bioaccumulation in Slovakia than in Kazakhstan in both songbirds and mice. The three songbird species from Kazakhstan showed differences due to different feeding niches. High levels were found in thrushes, which are considered insectivorous ground feeders, whereas the lowest mercury concentrations were detected in tits, which are considered more generalist feeders. In Slovakia, the trend was different, with tits having similar levels of Hg to thrushes, a reflection of the different levels of contamination of environmental components. Mice showed overall lower concentrations than birds at both sites.

Studies on the distribution characteristics and environmental relevance of per- and polyfluoroalkyl substances (PFAS) in waterbird feathers are scarce. In the present study, the concentrations of twenty-three PFAS in the remiges, coverts, body, down, and tail feathers of three common species of Ardeidae (little egret, grey heron, and Chinese pond-heron) in Poyang Lake were investigated. The total PFAS concentrations in the pinna and scapus were 38 – 42 ng/g dry weight (dw) and 21 – 38 ng/g dw, respectively; long-chain C9–14 perfluorocarboxylic acids were abundant in all feathers. Most PFAS accumulated in the pinna; however, perfluorohexane sulfonic acid and perfluorooctane sulfonamide were predominant in the scapus. The PFAS concentrations were higher in the tail and flight feathers than in the cover and body feathers. Furthermore, the concentrations of PFAS in waterbird feathers were comparable with those in fish and higher than those in benthic invertebrates, all of which originated from Poyang Lake. The PFAS profiles in feathers were significantly and positively correlated with those in fish (r > 0.71) and benthos (r > 0.43). These results suggest that waterbird feather is a suitable biomonitor of PFAS contamination in regional freshwater ecosystems.

Non-invasive proxies, such as fur and feathers, are likely to be increasingly used to assess the potential exposure of chemicals, including trace metals and metalloids. However, the amount of external contamination is usually unknown, and there is no standard method for removing external contamination of trace metals in fur or feathers. To date, 40 % of studies published related to the measurement of trace metal levels in fur or the hair of non-human mammals and 24 % of studies in feathers do not state any washing methods or did not wash the samples before analysis. We assessed three washing techniques to remove external contamination of arsenic (As), lead (Pb), and zinc (Zn) from bat fur. We selected the three most frequently used fur washing methods from literature. To test these methods, fur samples from great flying foxes (Pteropus neohibernicus neohibernicus, n=15 individuals) from Papua New Guinea preserved over eight decades (AMNH, USA) were used. Percentages of trace metal removed are 87.19 % (SD= 12.28), 92.99 % (SD= 5.5) and 88.57 % (SD= 9.33) for As, 54.72 % (SD= 31.64), 55.89 % (SD= 37.87), and 53.93 % (SD= 41.28) for Pb, and 74.03 % (SD= 22.96), 22.93 % (SD= 73), and 24.95 % (SD= 49.5) for Zn using M2, M3, and M4, respectively. We also assessed four washing techniques to remove external contamination of arsenic (As), mercury (Hg), and zinc (Zn) from bird feathers. We identified the four most prevalent washing techniques in the literature used for feathers. We used feathers from the great horned owl (Bubo virginianus) and the great blue heron (Ardea herodias) to test these methods. Percentages of trace metal removed are 34.35 % (SD= 44.22), 69.22 % (SD= 36.5), 62.59 % (SD= 48.37), and 80.89 % (SD= 14.54) for As, 66.97 % (SD= 13.26), 29.4 % (SD= 67.06), 49.68 % (SD= 42.33), and 28.88 % (SD= 69) for Hg, and

Bird plumage coloration is a complex and multifactorial process that involves both genetic and environmental factors. Diverse pigment groups contribute to plumage variation in different birds. In parrots, the predominant green color results from the combination of 2 different primary colors: yellow and blue. Psittacofulvin, a pigment uniquely found in parrots, is responsible for the yellow coloration, while blue is suggested to be the result of light scattering by feather nanostructures and melanin granules. So far, genetic control of melanin-mediated blue coloration has been elusive. In this study, we demonstrated that feather from the yellow mutant rose-ringed parakeet displays loss of melanosome granules in spongy layer of feather barb. Using whole genome sequencing, we found that mutation in SLC45A2, an important solute carrier protein in melanin synthetic pathway, is responsible for the sex-linked yellow phenotype in rose-ringed parakeet. Intriguingly, one of the mutations, P53L found in yellow Psittacula krameri is already reported as P58A/S in the human albinism database, known to be associated with human OCA4. We further showed that mutations in SLC45A2 gene affect melanin production also in other members of Psittaculidae family such as alexandrine and plum-headed parakeets. Additionally, we demonstrate that the mutations associated with the sex-linked yellow phenotype, localized within the transmembrane domains of the SLC45A2 protein, affect the protein localization pattern. This is the first evidence of plumage color variation involving SLC45A2 in parrots and confirmation of associated mutations in the transmembrane domains of the protein that affects its localization. [ABSTRACT FROM AUTHOR]

Geographic distribution models of environmentally stable isotopes (the so‐called "isoscapes") are widely employed in animal ecology, and wildlife forensics and conservation. However, the application of isoscapes is limited to elements and regions for which the spatial patterns have been estimated. Here, we focused on the ubiquitous yet less commonly used stable sulfur isotopes (δ34S). To predict the European δ34S isoscape, we used 242 feather samples from Eurasian Reed Warbler (Acrocephalus scirpaceus) formed at 69 European wetland sites. We quantified the relationships between sample δ34S and environmental covariates using a random forest regression model and applied the model to predict the geographic distribution of δ34S. We also quantified within‐site variation in δ34S and complementarity with other isotopes on both individual and isoscape levels. The predicted feather δ34S isoscape shows only slight differences between the central and southern parts of Europe while the coastal regions were most enriched in 34S. The most important covariates of δ34S were distance to coastline, surface elevation, and atmospheric concentrations of SO2 gases. The absence of a systematic spatial pattern impedes the application of the δ34S isoscape, but high complementarity with other isoscapes advocates the combination of multiple isoscapes to increase the precision of animal tracing. Feather δ34S compositions showed considerable within‐site variation with highest values in inland parts of Europe, likely attributed to wetland anaerobic conditions and redox sensitivity of sulfur. The complex European geography and topography as well as using δ34S samples from wetlands may contribute to the absence of a systematic spatial gradient of δ34S values in Europe. We thus encourage future studies to focus on the geographic distribution of δ34S using tissues from diverse taxa collected in various habitats over large land masses in the world (i.e., Africa, South America, or East Asia). [ABSTRACT FROM AUTHOR]

Feathers cause environmental problems worldwide when poultry processing industries produce it as a waste of billions of tons yearly. This waste is not easily decomposed by natural agents in a short time. Currently, Streptomyces spp. are known as a highly enzymatic activity species which can efficiently degrade feathers to products. Therefore, the aim of this study was to screen for Streptomyces strains with high feather-degrading activity. A total of 46 strains of Streptomyces spp. were isolated from different soils of Danang city and other vicinities, in which 13 isolates showed the ability to degrade casein and gelatin. The protease activity of H3, N5, and N7 isolates were higher than others. In particular, N7 strain had the highest protease activity with 70.33 U/mL and degraded 97.79% feather after 5 days of cultivation. Based on the sequence analysis of 16S rRNA, N7 was identified as homologous to Streptomyces anandii.

As a nondestructive means of environmental monitoring, bird feathers have been used to analyze levels of per- and polyfluoroalkyl substances (PFASs) in specific environments. In this study, feather samples from 10 waterbird species around Poyang Lake were collected, and a pretreatment method for PFASs in feathers was optimized. The results showed that a combined cleaning method using ultrapure water and n-hexane effectively removed external PFASs. Twenty-three legacy and emerging PFASs were identified in the feathers of waterbirds, of which hexafluoropropylene oxides (HFPOs), chlorinated polyfluoroalkyl ether sulfonates (Cl-PFESAs), and sodium p-perfluorinated noneoxybenzene sulfonate (OBS) were reported for the first time, with their concentrations ranging from 0.060–2.4 ng·g−1 dw, 0.046–30 ng·g−1 dw, and lower than the method detection limit to 30 ng·g−1 dw, respectively. Compound- and species-specific bioaccumulation of PFASs was observed in the feathers of different waterbird species, suggesting that different PFAS types can be monitored through the selection of different species. Moreover, the concentrations of most PFCAs (except perfluorobutyric acid), perfluorooctane sulfonate (PFOS), and perfluorooctane sulfonamide (FOSA) were significantly positively correlated with δ15N (p < 0.05), while the concentrations of HFPOs, Cl-PFESAs, and OBS had significant positive correlations with δ13C. This indicates that the bioaccumulation of legacy and emerging PFASs in waterbird feathers is affected by their trophic level, feeding habits, and foraging area.

Abstract Geographic distribution models of environmentally stable isotopes (the so‐called “isoscapes”) are widely employed in animal ecology, and wildlife forensics and conservation. However, the application of isoscapes is limited to elements and regions for which the spatial patterns have been estimated. Here, we focused on the ubiquitous yet less commonly used stable sulfur isotopes (δ34S). To predict the European δ34S isoscape, we used 242 feather samples from Eurasian Reed Warbler (Acrocephalus scirpaceus) formed at 69 European wetland sites. We quantified the relationships between sample δ34S and environmental covariates using a random forest regression model and applied the model to predict the geographic distribution of δ34S. We also quantified within‐site variation in δ34S and complementarity with other isotopes on both individual and isoscape levels. The predicted feather δ34S isoscape shows only slight differences between the central and southern parts of Europe while the coastal regions were most enriched in 34S. The most important covariates of δ34S were distance to coastline, surface elevation, and atmospheric concentrations of SO2 gases. The absence of a systematic spatial pattern impedes the application of the δ34S isoscape, but high complementarity with other isoscapes advocates the combination of multiple isoscapes to increase the precision of animal tracing. Feather δ34S compositions showed considerable within‐site variation with highest values in inland parts of Europe, likely attributed to wetland anaerobic conditions and redox sensitivity of sulfur. The complex European geography and topography as well as using δ34S samples from wetlands may contribute to the absence of a systematic spatial gradient of δ34S values in Europe. We thus encourage future studies to focus on the geographic distribution of δ34S using tissues from diverse taxa collected in various habitats over large land masses in the world (i.e., Africa, South America, or East Asia).

The present study evaluated the potential utility of feather samples for the convenient and accurate detection of avian influenza virus (AIV) in commercial poultry. Feather samples were obtained from AIV-negative commercial layer facilities in Iowa, USA. The feathers were spiked with various concentrations (106 to 100) of a low pathogenic strain of H5N2 AIV using a nebulizing device and were evaluated for the detection of viral RNA using a real-time RT-PCR assay immediately or after incubation at −20, 4, 22, or 37 °C for 24, 48, or 72 h. Likewise, cell culture medium samples with and without the virus were prepared and used for comparison. In the spiked feathers, the PCR reliably (i.e., 100% probability of detection) detected AIV RNA in eluates from samples sprayed with 103 EID50/mL or more of the virus. Based on half-life estimates, the feathers performed better than the corresponding media samples (p < 0.05), particularly when the samples were stored at 22 or 37 °C. In conclusion, feather samples can be routinely collected from a poultry barn as a non-invasive alternative to blood or oropharyngeal–cloacal swab samples for monitoring AIV. [ABSTRACT FROM AUTHOR]

Feathers are most important parts of avian and commonly found at scene of crime. The identification of species from feather samples could help in crime investigation particularly wildlife trafficking cases. Analysis of such evidence can provide a link between the criminal and the crime scene and thereby be utilized as associative evidence in the court of law. In the present study, twelve feather samples of Galliformes bird has been analysed using ATR-FTIR spectroscopy. Chemometric methods such as Principal Component Analysis (PCA) and Linear Discrimination Analysis (LDA) were performed on the obtained spectra for objective interpretation of results. PC1, PC2, PC3, and PC4 were able to explain a variance of 93 %, 4 %, 2 %, and 1 % respectively. The score plots showed separate clusters for all twelve bird species. The LDA model classified all the twelve species into their respective categories with a 100 % accuracy. Overall, the presented methodology has shown a potential for application in forensic casework

Immature feathers are known replication sites for high pathogenicity avian influenza viruses (HPAIVs) in poultry. However, it is unclear whether feathers play an active role in viral transmission. This study aims to investigate the contribution of the feather epithelium to the dissemination of clade 2.3.4.4b goose/Guangdong/1996 lineage H5 HPAIVs in the environment, based on natural and experimental infections of domestic mule and Muscovy ducks. During the 2016–2022 outbreaks, H5 HPAIVs exhibited persistent and marked feather epitheliotropism in naturally infected commercial ducks. Infection of the feather epithelium resulted in epithelial necrosis and disruption, as well as the production and environmental shedding of infectious virions. Viral and feather antigens colocalized in dust samples obtained from poultry barns housing naturally infected birds. In summary, the feather epithelium contributes to viral replication, and it is a likely source of environmental infectious material. This underestimated excretion route could greatly impact the ecology of HPAIVs, facilitating airborne and preening-related infections within a flock, and promoting prolonged viral infectivity and long-distance viral transmission between poultry farms.

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The knowledge of migratory connectivity is important for understanding the potential drivers of populations and it is thus important for conservation implications. Migratory connectivity of species can be studied using exogenous, such as rings and transmitters, or endogenous markers, such as stable isotopes and trace elements. The use of trace elements has been much less frequently studied compared to stable isotopes. Trace elements can be studied from the feathers of birds and this does not necessarily require trapping of individuals. Here we studied the variation of 18 different trace elements in feathers of two long‐distance trans‐African migrants, willow warblers Phylloscopus trochilus and barn swallows Hirundo rustica, using body feathers of museum specimens of birds from Finnish breeding grounds. The trace elements were measured using laser‐ablation inductively‐coupled‐plasma mass‐spectrometry (LA‐ICP‐MS). We show that trace element concentrations were relatively stable along the rachis within the same feather except in Ni and S, which showed a quadratic pattern. In general, variation within feathers of the same individuals was smaller than in feathers between individuals for most elements. Furthermore, concentrations of 11 trace elements showed significantly higher concentrations in willow warbler feathers collected in spring than in autumn, moulted in African wintering grounds and European breeding grounds, respectively. Last, concentrations of seven trace elements were significantly higher in the spring feathers of willow warblers compared to barn swallows. This suggests that trace elements could be used to separate moulting grounds of the birds on the larger scale within the same species, but also sampling design should be carefully considered. [ABSTRACT FROM AUTHOR]

Background: A major portion of poultry feather waste is constituted by keratin, which is recalcitrant to degradation by common proteases. Feather waste contributes to a significant volume of biowaste load to the environment. Valorization of these wastes into various products has been attempted by many researchers. The present study aimed to produce peptides (molecular weight

The increase in the generation of chicken feathers, due to the large production of the poultry industry, has created the need to search for ecologically safer ways to manage these residues. As a sustainable alternative for recycling keratin waste, we investigated the ability of the bacterium Ochrobactrum intermedium to hydrolyze chicken feathers and the valorization of the resulting enzymes and protein hydrolysate. In submerged fermentation with three different inoculum sizes (2.5, 5.0, and 10.0 mg of bacterial cells per 50 mL of medium), the fastest degradation of feathers was achieved with 5.0 mg cells, in which a complete decomposition of the substrate (96 h) and earlier peaks of keratinolytic and caseinolytic activities were detected. In the resulting protein hydrolysate, we noticed antioxidant and Fe2+ and Cu2+ chelating activities. ABTS scavenging, Fe3+-reducing ability and metal chelating activities of the fermentative samples followed the same trend of feather degradation; as feather mass decreased in the media, these activities increased. Furthermore, we noticed about 47% and 60% dispersion of established 7-day biofilms formed by S. aureus after enzymatic treatment for 5 h and 24 h, respectively. These findings highlight the potential use of this bacterium as an environmentally friendly alternative to treat this poultry waste and offer valuable products. [ABSTRACT FROM AUTHOR]

A distinctive isolate was discovered and visually recognized as a member of the genus Didymella during a routine examination of Coelomycetes isolated from diverse fruit juices. Based on sequencing of the internal transcribed spacer (ITS), the fungus was identified as Didymella keratinophila since it showed a 100% identity to the type strain. The strain thrived and produced keratinase and collagenase enzymes by hydrolyzing native chicken feathers in submerged fermentation (SmF). After 10 days of fermentation at 30 °C, pH 9 using sodium nitrate as a nitrogen supply produced the highest keratinase activity of 8780 ± 620 U/mL/min, while pH 6 and beef extract produced the maximum collagenase activity of 11,230 ± 1290 U/mL/min. The partially-purified keratinase enzyme worked best at pH 7.0 and 45 °C, exhibiting a specific activity of 44,903 ± 1555 U/mg protein. The activity of the partially-purified collagenase enzyme was excellent at pH 6.0 at 35 °C, generating 15,753 ± 110 U/mg enzyme-specific activity. Mn2+ and K+ were the most efficient inhibitors of keratinases and collagenase, respectively. Both EDTA and metal ions significantly decreased the activity of keratinase and collagenase. This report identified a workable supplier of collagenase and keratinase enzymes derived from chicken feathers, offering a reliable way to exploit and manage these wastes for obtaining high-value products. [ABSTRACT FROM AUTHOR]

All living jawed vertebrates possess teeth or did so ancestrally. Integumental surface also includes the cornea. Conversely, no other anatomical feature differentiates the clades so readily as skin appendages do, multicellular glands in amphibians, hair follicle/gland complexes in mammals, feathers in birds, and the different types of scales. Tooth-like scales are characteristic of chondrichthyans, while mineralized dermal scales are characteristic of bony fishes. Corneous epidermal scales might have appeared twice, in squamates, and on feet in avian lineages, but posteriorly to feathers. In contrast to the other skin appendages, the origin of multicellular glands of amphibians has never been addressed. In the seventies, pioneering dermal–epidermal recombination between chick, mouse and lizard embryos showed that: (1) the clade type of the appendage is determined by the epidermis; (2) their morphogenesis requires two groups of dermal messages, first for primordia formation, second for appendage final architecture; (3) the early messages were conserved during amniotes evolution. Molecular biology studies that have identified the involved pathways, extending those data to teeth and dermal scales, suggest that the different vertebrate skin appendages evolved in parallel from a shared placode/dermal cells unit, present in a common toothed ancestor, c.a. 420 mya. [ABSTRACT FROM AUTHOR]

Stable isotope analysis of feathers is widely used in bird ecology. Generally, studied birds should be captured to collect feather samples in a way that clarifies the attribution of feather samples. As some endangered birds cannot be captured, feather sampling is the only feasible method for isotopic research. However, whether it can be used for research on individuals remains to be clarified. In this study, the values of d13C and d15N of the rachises and barbules of 27 feathers from 3 pigeons were measured, and cluster analysis of these samples was carried out by using the system clustering method. The results showed a significant difference between the isotope values of the rachis and barbules from the same feather. In addition, the isotope values of the rachises and barbules differed between individuals, although the food sources of the samples might be slightly different. Based on the above results, the cluster analysis was able to distinguish individuals, with the highest accuracy of 85%; the more factors that were used, the higher the accuracy of the clustering. [ABSTRACT FROM AUTHOR]

The cross-linking of structural proteins is critical for establishing the mechanical stability of the epithelial compartments of the skin and skin appendages. The introduction of isopeptide bonds between glutamine and lysine residues depends on catalysis by transglutaminases and represents the main protein cross-linking mechanism besides the formation of disulfide bonds. Here, we used a fluorescent labeling protocol to localize the activity of transglutaminases on thin sections of the integument and its appendages in mammals and birds. In human tissues, transglutaminase activity was detected in the granular layer of the epidermis, suprabasal layers of the gingival epithelium, the duct of sweat glands, hair follicles and the nail matrix. In the skin appendages of chickens, transglutaminase activity was present in the claw matrix, the feather follicle sheath, the feather sheath and in differentiating keratinocytes of feather barb ridges. During chicken embryogenesis, active transglutaminase was found in the cornifying epidermis, the periderm and the subperiderm. Transglutaminase activity was also detected in the filiform papillae on the tongue of mice and in conical papillae on the tongue of chickens. In summary, our study reveals that transglutaminase activities are widely distributed in integumentary structures and suggests that transglutamination contributes to the cornification of hard skin appendages such as nails and feathers. [ABSTRACT FROM AUTHOR]

The present study evaluated the potential utility of feather samples for the convenient and accurate detection of avian influenza virus (AIV) in commercial poultry. Feather samples were obtained from AIV-negative commercial layer facilities in Iowa, USA. The feathers were spiked with various concentrations (106 to 100) of a low pathogenic strain of H5N2 AIV using a nebulizing device and were evaluated for the detection of viral RNA using a real-time RT-PCR assay immediately or after incubation at −20, 4, 22, or 37 °C for 24, 48, or 72 h. Likewise, cell culture medium samples with and without the virus were prepared and used for comparison. In the spiked feathers, the PCR reliably (i.e., 100% probability of detection) detected AIV RNA in eluates from samples sprayed with 103 EID50/mL or more of the virus. Based on half-life estimates, the feathers performed better than the corresponding media samples (p < 0.05), particularly when the samples were stored at 22 or 37 °C. In conclusion, feather samples can be routinely collected from a poultry barn as a non-invasive alternative to blood or oropharyngeal–cloacal swab samples for monitoring AIV.

In the French Mediterranean plain, the northern extreme of its native range, the Iberian gray shrike, Lanius meridionalis, predominantly feeds on arthropods. Its type of loral plumage plays a key role in protecting its eyes while transporting large prey. The aims are to understand the role played by feathers in protecting the animal from various types of defensive prey. I combine an inspection of large insect prey types found on larders with a review of bird specimens found in museum collections to examine the morphometric characteristics of rictal feathers and culmen. In addition, precision photographs are used to observe the posture of the plumage in natura. I could identify four categories of protective feathers: clustered bristles, semi‐bristles, semi‐plumes distributed in the loral area, and semi‐plumes above the eyes. My results suggest that the Iberian gray shrike has a complex structure of loral feathers, specific to its foraging activity and prey types. The presence of these rictal bristles is probably a protection against the movements of larger prey items, which might damage loral zone of Lanius meridionalis. [ABSTRACT FROM AUTHOR]

Determining the sex of individuals in sexually monomorphic bird species outside of the breeding season is difficult. However, many monochromatic species exhibit sex differences in morphometrics, including wing chord length. For example, recent studies found that the Puget Sound ( pugetensis ) and Gambel’s ( gambelii ) subspecies of White-crowned Sparrow ( Zonotrichia leucophrys ) can be sexed reliably using wing chord length. However, the Eastern subspecies ( leucophrys ) has not been evaluated. We measured the wing chord length of Eastern White-crowned Sparrows migrating through the Long Point Bird Observatory and specimens from the Fatal Light Awareness Program to determine if this subspecies can be reliably sexed using wing chord length. We combined wing chord length measurements with molecular sexing to test the prediction that males have a significantly longer wing chord length than females. Unfortunately, we only captured one definitive-cycle female and were thus unable to test our prediction in definitive-cycle birds. Males in first-cycle plumage had significantly longer wing chord lengths than females in first-cycle plumage and, outside of an overlapping range (74–76 mm), this subspecies can be reliably sexed using wing chord length. Our results support the use of wing chord length as a tool for bird banders and researchers to determine the sex of Eastern White-crowned Sparrows in first-cycle plumage in the hand outside of their breeding season or in the absence of a cloacal protuberance or brood patch.

Plastic materials have become a necessity of human life especially in the packaging of food commodities and biomedical procedures. Bioplastic is emerging as an effective alternative to fossil oil-based materials to avoid the environmental hazards of the plastic industry. During this study, chicken feathers were used as a substrate to isolate keratin degrading bacteria. Among 14 identified isolates, Bacillus sp BAM3 was found to be the most promising isolate. Partial 16S rDNA analysis-based molecular characterization revealed it is a strain of Bacillus cereus. Bacillus sp BAM3 can grow and produce keratinase in feathers containing basal medium as the sole carbon and energy source. The maximum keratinase production (730U/ml) was achieved within 24 h under optimum reaction conditions. The optimized reaction pH and temperature were noted as 9.0 and 50 °C for crude keratinase activity, respectively. The chicken feathers were used as a substrate in 2, 5, and 10 wt% glycerol to synthesize keratin-based bioplastic with keratinolytic bacterium Bacillus cereus BAM3. Bioplastic prepared from keratin with 2% of glycerol was found to possess good mechanical properties. Therefore, the results present a novel keratinolytic isolate of Bacillus cereus BAM3, which may have potential biotechnological applications in keratin hydrolysis processes. The development of keratin-based bioplastics possessing superior crystalline morphology requires further investigations to substitute fossil oil-based materials.

Abstract Wing area, wing loading, and aspect ratio are key variables for studies of avian comparative ecology, despite the complexity of measuring wing characteristics in living and museum specimens. The systematic databases of feather photographs available on the Internet may offer an alternative way of obtaining such morphometric data. Here, we evaluate whether measurements of scanned feathers from web photograph databases may offer reliable estimates of avian morphometry. Published data on wing area were obtained for 317 bird species and feather measurements from web photograph databases for 225 of them. A variable termed “lift generation area,” a proxy for wing area, was calculated for each species on the basis of the mean length of the five distal secondary feathers and wingspan data from literature. The fit between this proposed variable and data extracted from the literature was examined by correlation, employing linear regression to explore the lack of fit among species. “Lift generation area” proved to be highly informative as a proxy for wing area for the study species as a whole (R2 > .98). Discrepancies observed between species were strongly negatively associated with the size of the original sample used to calculate wing area (p = .001) and, to a lesser extent, with bird size (p = .023), but not with aspect ratio. It was also found that the mean value of the mismatch between “lift generation area” and wing area (13.1%) among the study species as a whole was of similar magnitude to that found between sources of bibliographic wing area data for the 64 species for which two published estimates of this variable were available (15.3%). We conclude that measurements made from feather photograph databases are reliable for use in studies of avian comparative ecology, enabling the inclusion of biomechanical parameters of many more species than featured at present.

Conversion of feather and blood from chicken slaughterhouse waste for producing solid and liquid organic fertilizer excluding composting process with a variation of the mass ratio of feather and blood of a chicken has been conducted. The nitrogen, sulfur, and iron content in the solid and liquid product of the hydrothermal carbonization process were analyzed to identify and characterize the possibility of hydrolysate as a source of nitrogen, sulfur, and iron in soil fertilizer. Feather and blood of chicken waste were introduced to a hydrothermal carbonization reactor with the addition of limestone at a temperature range of 160–170 °C for the preparation of solid and liquid organic fertilizer. According to the FTIR interpretation, the solid product had functional groups such as NH, OH, CH sp3, SH, C=O, C=C, C–O–C, and C–H aromatic. The nitrogen, sulfur, and iron content of the optimal ratio in the solid phase were 4.67%, 1.63%, and 3694.56 ppm, while their contents in the liquid fertilizer were 3.76%, 1.80%, and 221.56 ppm, respectively. The vibration of 478 cm–1 is attributed to Fe–O paramagnetic (Fe2O3) confirmed by TEM images showed the diameter size less than 20 nm indicating the presence of superparamagnetic material.

Geotextiles are used for separation, drainage, filtration and anti-erosion protection sealing, as well as to improve plant vegetation conditions. The research objective of this study was to verify the influence of the addition of poultry feathers on accelerating the biodegradation of nonwovens in cultivated soil. The tests were carried out in laboratory conditions and were based on the assessment of weight loss. The experiments confirmed the positive effects of the presence of waste that was rich in keratin on the time required for the biodegradation of the tested materials (the period of biodegradation was 8–24 weeks). Additionally, the influence of the biodegradation of the tested materials on the ecotoxicity was investigated and showed no negative effects on the microbiological activity (106 cfu). The research also included the determination of the carbon to nitrogen ratio of the test medium (blank, 12–14:1; with feather addition, 19–20:1). A statistical analysis revealed a correlation between the mechanical properties and the period of biological decomposition. This research was an important step for the management of poultry feather waste in agricultural applications. The tested materials could be seen an alternative that meets all ecological criteria, which seems to be a golden solution that not only allows the delivery of important nutrients to the soil, but also manages waste in an environmentally safe manner. [ABSTRACT FROM AUTHOR]

The validation of the use of primary cell lines from non-lethal matrixes of feathers and blood of nestlings of a wild bird species, the tawny owl (Strix aluco) is described. Tawny Owl Feather Fibroblast (TOFF) cells and peripheral blood mononuclear cells (PBMCs) were isolated and cultured from the pulp of the secondary wing feathers and whole blood respectively from free-living tawny owl nestlings. Cell growth was registered up until 48 h for both the PBMC cells and the TOFFs. The validation of these primary cell lines in free-living birds has the potential to advance the assessment of immunotoxicological effects in wildlife via non-lethal manner. They provide a key tool with which to study cell toxicity and responses to environmental stressors on a cellular level in wild bird species of interest. [ABSTRACT FROM AUTHOR]

Simple Summary: This study seeks to test the effect of burial/exposure, sediment type, the addition of feather-degrading microbes, and the addition of minerals on feather preservation, and for the first time, compares these states in ambient vs. elevated CO2 atmospheres to test the effect of CO2 on degradation and/or preservation under various depositional settings. The exceptional preservation of feathers in the fossil record has led to a better understanding of both phylogeny and evolution. Here we address factors that may have contributed to the preservation of feathers in ancient organisms using experimental taphonomy. We show that the atmospheres of the Mesozoic, known to be elevated in both CO2 and with temperatures above present levels, may have contributed to the preservation of these soft tissues by facilitating rapid precipitation of hydroxy- or carbonate hydroxyapatite, thus outpacing natural degradative processes. Data also support that that microbial degradation was enhanced in elevated CO2, but mineral deposition was also enhanced, contributing to preservation by stabilizing the organic components of feathers. [ABSTRACT FROM AUTHOR]

Sex determination of of straw-headed bulbul offspring was carried out from 27 offspring's plucked feather samples in a captive breeding program. Using direct PCR, this study provided more evidences that feather samples are reliable as a source of DNA for non-invasive and effective molecular sexing. The study also revealed that the offspring sex ratio of straw-headed bulbul was slightly inclined towards males, but there was no significant difference from the value of 0.5. [ABSTRACT FROM AUTHOR]

Soil samples were collected from the feather dumped area where Bacillus pumilus was isolated and used for keratinase production and keratinolytic activity. In the optimization study, optimal condition for enzyme production was observed at 144 h, pH 7, temperature 37°C. The organism was utilized for feather degradation study. The maximum degradation of 57% was obtained at 37°C, pH 7 and 6 days incubation. The size of keratinase was determined by SDS- PAGE and was observed as 52 KDa.

This study was conducted to explore the regulatory role of methionine (Met) in feather follicle and feather development during the embryonic period of chicks. A total of 280 fertile eggs (40 eggs/group) were injected with 0, 5, 10, 20 mg of L-Met or DL-Met/per egg on embryonic day 9 (E9), and whole-body feather and skin tissues were collected on E15 and the day of hatching (DOH). The whole-body feather weight was determined to describe the feather growth, and the skin samples were subjected to hematoxylin and eosin staining and Western blotting for the evaluation of feather follicle development and the expressions of Wingless/Int (Wnt)/β-catenin signaling pathway proteins, respectively. The results showed that L- or DL-Met did not affect the embryo weight (P > 0.05), but increased the absolute and relative whole-body feather weights. Specifically, 5 and 10 mg of L-Met and 5, 10, and 20 mg of DL-Met significantly increased the absolute feather weight at E15 (P 0.05). The levels of L- and DL-Met were quadratically correlated with the absolute and relative feather weights of chicks on the DOH (P

All living jawed vertebrates possess teeth or did so ancestrally. Integumental surface also includes the cornea. Conversely, no other anatomical feature differentiates the clades so readily as skin appendages do, multicellular glands in amphibians, hair follicle/gland complexes in mammals, feathers in birds, and the different types of scales. Tooth-like scales are characteristic of chondrichthyans, while mineralized dermal scales are characteristic of bony fishes. Corneous epidermal scales might have appeared twice, in squamates, and on feet in avian lineages, but posteriorly to feathers. In contrast to the other skin appendages, the origin of multicellular glands of amphibians has never been addressed. In the seventies, pioneering dermal–epidermal recombination between chick, mouse and lizard embryos showed that: (1) the clade type of the appendage is determined by the epidermis; (2) their morphogenesis requires two groups of dermal messages, first for primordia formation, second for appendage final architecture; (3) the early messages were conserved during amniotes evolution. Molecular biology studies that have identified the involved pathways, extending those data to teeth and dermal scales, suggest that the different vertebrate skin appendages evolved in parallel from a shared placode/dermal cells unit, present in a common toothed ancestor, c.a. 420 mya.

A distinctive isolate was discovered and visually recognized as a member of the genus Didymella during a routine examination of Coelomycetes isolated from diverse fruit juices. Based on sequencing of the internal transcribed spacer (ITS), the fungus was identified as Didymella keratinophila since it showed a 100% identity to the type strain. The strain thrived and produced keratinase and collagenase enzymes by hydrolyzing native chicken feathers in submerged fermentation (SmF). After 10 days of fermentation at 30 °C, pH 9 using sodium nitrate as a nitrogen supply produced the highest keratinase activity of 8780 ± 620 U/mL/min, while pH 6 and beef extract produced the maximum collagenase activity of 11,230 ± 1290 U/mL/min. The partially-purified keratinase enzyme worked best at pH 7.0 and 45 °C, exhibiting a specific activity of 44,903 ± 1555 U/mg protein. The activity of the partially-purified collagenase enzyme was excellent at pH 6.0 at 35 °C, generating 15,753 ± 110 U/mg enzyme-specific activity. Mn2+ and K+ were the most efficient inhibitors of keratinases and collagenase, respectively. Both EDTA and metal ions significantly decreased the activity of keratinase and collagenase. This report identified a workable supplier of collagenase and keratinase enzymes derived from chicken feathers, offering a reliable way to exploit and manage these wastes for obtaining high-value products.

Avians have evolved many different modes of flying as well as various types of feathers for adapting to varied environments. However, the protein content and ratio of protein secondary structures (PSSs) in mature flight feathers are less understood. Further research is needed to understand the proportions of PSSs in feather shafts adapted to various flight modes in different avian species. Flight feathers were analyzed in chicken, mallard, sacred ibis, crested goshawk, collared scops owl, budgie, and zebra finch to investigate the PSSs that have evolved in the feather cortex and medulla by using nondestructive attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). In addition, synchrotron radiation-based, Fourier transform infrared microspectroscopy (SR-FTIRM) was utilized to measure and analyze cross-sections of the feather shafts of seven bird species at a high lateral resolution to resolve the composition of proteins distributed within the sampled area of interest. In this study, significant amounts of α-keratin and collagen components were observed in flight feather shafts, suggesting that these proteins play significant roles in the mechanical strength of flight feathers. This investigation increases our understanding of adaptations to flight by elucidating the structural and mechanistic basis of the feather composition.

The poultry industry produces millions of tons of feathers waste that can be transformed into valuable products through bioprocess. The study describes the enhanced keratinase and feather hydrolysate production by Bacillus subtilis AMR. The metabolism of each microorganism is unique, so optimization tools are essential to determine the best fermentation parameters to obtain the best process performance. The evaluation of different propagation media indicated the constitutive production of two keratinases of approximately 80 kDa. The combination of Mn2+, Ca2+, and Mg2+ at 0.5 mM improved the keratinolytic activity and feather degradation 1.5-fold, while Cu2+ inhibited the enzymatic activity completely. Replace yeast extract for sucrose increased the feather hydrolysate production three times. The best feather concentration for hydrolysate production was 1.5% with an inoculum of 108 CFU/mL and incubation at 30 °C. None of the inorganic additional nitrogen sources tested increased hydrolysate production, although (NH4)2SO4 and KNO3 improved enzymatic activity. The optimization process improved keratinolytic activity from 205.4 to 418.7 U/mL, the protein concentration reached 10.1 mg/mL from an initial concentration of 3.9 mg/mL, and the feather degradation improved from 70 to 96%. This study characterized keratinase and feather hydrolysate production conditions offering valuable information for exploring and utilizing AMR keratinolytic strain for feather valorization. [ABSTRACT FROM AUTHOR]

Carotenoids are pigments responsible for most bright yellow, red, and orange hues in birds. Their distribution has been investigated in avian plumage, but the evolution of their expression in skin and other integumentary structures has not been approached in detail. Here, we investigate the expression of carotenoid‐consistent coloration across tissue types in all extant, nonpasserine species (n = 4022) and archelosaur outgroups in a phylogenetic framework. We collect dietary data for a subset of birds and investigate how dietary carotenoid intake may relate to carotenoid expression in various tissues. We find that carotenoid‐consistent expression in skin or nonplumage keratin has a 50% probability of being present in the most recent common ancestor of Archosauria. Skin expression has a similar probability at the base of the avian crown clade, but plumage expression is unambiguously absent in that ancestor and shows hundreds of independent gains within nonpasserine neognaths, consistent with previous studies. Although our data do not support a strict sequence of tissue expression in nonpasserine birds, we find support that expression of carotenoid‐consistent color in nonplumage integument structures might evolve in a correlated manner and feathers are rarely the only region of expression. Taxa with diets high in carotenoid content also show expression in more body regions and tissue types. Our results may inform targeted assays for carotenoids in tissues other than feathers, and expectations of these pigments in nonavian dinosaurs. In extinct groups, bare‐skin regions and the rhamphotheca, especially in species with diets rich in plants, may express these pigments, which are not expected in feathers or feather homologues. [ABSTRACT FROM AUTHOR]

ABSTRACT: The feather corticosterone concentration (fCORT) is increasingly used to assess long-term stress in birds as this indicator provides the potential to retrospectively evaluate the adrenocortical activity of a bird during the growth period of a feather over several weeks in one sample. However, there is still a lack of knowledge concerning external factors which can potentially influence fCORT in birds. The aim of the present study was to determine whether fCORT in laying hens is affected by previous fecal contamination of the plumage. Fully grown primaries 5 (P5s) of laying hens (n = 40) were used for the study. To test the effects of fecal contamination on fCORT, freshly defecated droppings from laying hens were collected and mixed manually. In order to simulate practical and at the same time standardized contamination, the upper surface of the previously determined middle third of the right P5 of each hen then was evenly coated with the paste prepared from fresh feces. The treated feathers were stored for 24 h protected from light at room temperature under a film cover to prevent evaporation. Thereafter, the applied layer of excreta was removed manually. Contralateral P5s of the same individuals were stored under identical conditions and served as controls. Both treatment and control feathers were washed in an aqueous soap solution, rinsed several times in pure water and air-dried subsequently. After pulverization and methanolic extraction, fCORT was analyzed by ELISA. The mean fCORT of treatment P5s (reference ‘feather length’: 12.88 ± 3.16 pg/mm; reference ‘feather weight’: 7.81 pg/mg ± 1.86 pg/mg) were significantly higher (P < 0.001) than those of control P5s (reference ‘feather length’: 9.76 ± 2.42 pg/mm; reference ‘feather weight’: 5.93 ± 1.44 pg/mg). Our results show that previous contamination with excreta can increase fCORT, which was detectable even after a washing procedure prior to analysis. In conclusion, fecal contamination of feathers is a significant influencing factor that has to be considered when applying fCORT measurements.

Mercury (Hg), a persistent potent neurotoxin, poses a serious hazard to human and wildlife health. Although highly elevated concentrations were documented in the environmental compartments of China, very few investigations were conducted regarding Hg bioaccumulation in terrestrial vertebrates, particularly avian species at the top trophic position. To assess to what degree the predatory raptors are subject to Hg contamination, we measured feather Hg concentrations from two diurnal raptors, two nocturnal owls, and one predatory passerine, collected from Northeast China. Results showed that the feather Hg concentrations were not greater than 3.67 mg/kg. Notably, there is a significant difference in feather Hg among species: Brown Shrike > Amur Falcon = Common Kestrel > Long-eared Owl > Little Owl. Brown Shrike had the highest feather Hg (1.27 ± 0.91 mg/kg), approximately three times higher compared to the diurnal predators (0.41 ± 0.33 mg/kg), and about seven-folds higher than the owls (0.18 ± 0.19 mg/kg). There were no differences in Hg concentrations between the tips of primary and tail feathers, but their correlations were significantly positive (between 0.45 and 0.96). Overall, the primary Hg = 0.15 + 0.74 × tail Hg (R2 = 0.61). Specifically, a great correlation between the primaries and tails in owls, while a weaker but significant correlation found in falcons/shrikes, provides insight into Hg content in feather tracts for biomonitoring. Our research is among the few studies regarding Hg contamination in the terrestrial predatory avian population in China. We discussed the influencing factors, the ecotoxicological risks to the terrestrial/marine avian population, and the limitations of this research.

Non-invasive proxies, such as fur and feathers, are likely to be increasingly used to assess the potential exposure of chemicals, including trace metals and metalloids. However, the amount of external contamination is usually unknown, and there is no standard method for removing external contamination of trace metals in fur or feathers. To date, 40 % of studies published related to the measurement of trace metal levels in fur or the hair of non-human mammals and 24 % of studies in feathers do not state any washing methods or did not wash the samples before analysis. We assessed three washing techniques to remove external contamination of arsenic (As), lead (Pb), and zinc (Zn) from bat fur. We selected the three most frequently used fur washing methods from literature. To test these methods, fur samples from great flying foxes (Pteropus neohibernicus neohibernicus , n=15 individuals) from Papua New Guinea preserved over eight decades (AMNH, USA) were used. Percentages of trace metal removed are 87.19 % (SD= 12.28), 92.99 % (SD= 5.5) and 88.57 % (SD= 9.33) for As, 54.72 % (SD= 31.64), 55.89 % (SD= 37.87), and 53.93 % (SD= 41.28) for Pb, and 74.03 % (SD= 22.96), 22.93 % (SD= 73), and 24.95 % (SD= 49.5) for Zn using M2, M3, and M4, respectively. We also assessed four washing techniques to remove external contamination of arsenic (As), mercury (Hg), and zinc (Zn) from bird feathers. We identified the four most prevalent washing techniques in the literature used for feathers. We used feathers from the great horned owl (Bubo virginianus) and the great blue heron (Ardea herodias) to test these methods. Percentages of trace metal removed are 34.35 % (SD= 44.22), 69.22 % (SD= 36.5), 62.59 % (SD= 48.37), and 80.89 % (SD= 14.54) for As, 66.97 % (SD= 13.26), 29.4 % (SD= 67.06), 49.68 % (SD= 42.33), and 28.88 % (SD= 69) for Hg, and <0 % (SD= 80.1), 0 % (SD= 29.55), 11.23 % (SD= 47.73), and 57.09 % (SD= 21.2) for Zn using M2, M3, M4, and M5, respectively. This study shows the importance of washing fur and feather samples prior to trace metals analyses in ecotoxicology and biomonitoring studies. • External contamination overestimates metal levels without prior washing • Acetone and detergent are the most effective reagents • Washing reagents on these matrices prior to metal analyses is metal specific • No washing procedure has yet ensured total removal of exogenous contamination [ABSTRACT FROM AUTHOR]

Abstract Measuring corticosterone in feathers has become an informative tool in avian ecology, enabling researchers to investigate carry‐over effects and responses to environmental variability. Few studies have, however, explored whether corticosterone is the only hormone expressed in feathers and is the most indicative of environmental stress. Essential questions remain as to how to compare hormone concentrations across different types of feathers and whether preening adds steroids, applied after feather growth. We used liquid chromatography coupled to tandem mass spectrometry to quantify a suite of 11 steroid hormones in back, breast, tail, and primary feathers naturally grown at overlapping time intervals by rhinoceros auklet Cerorhinca monocerata captive‐reared fledglings and wild‐caught juveniles. The captive‐reared birds were raised on either a restricted or control diet. Measured steroids included intermediates in the adrenal steroidogenesis pathway to glucocorticoids and the sex steroids pathway to androgens and estrogens. Corticosterone was detected in the majority of feathers of each type. We also detected cortisone in back feathers, androstenedione in breast feathers, and testosterone in primary feathers. Captive fledglings raised on a restricted diet had higher concentrations of corticosterone in all four feather types than captive fledglings raised on a control diet. Corticosterone concentrations were reliably repeatable across feather types when standardized for feather mass, but not for feather length. Of the seven hormones looked for in uropygial gland secretions, only corticosterone was detected in one out of 23 samples. We conclude that corticosterone is the best feather‐steroid biomarker for detection of developmental nutritional stress, as it was the only hormone to manifest a signal of nutritional stress, and that exposure to stress can be compared among different feather types when corticosterone concentrations are standardized by feather mass.