Search

The microbiome of the uropygial gland and integuments where birds spread the uropygial secretion may play crucial roles for their hosts, but it has been poorly studied, especially in wild species. Exploring bacterial communities associated with the uropygial secretion of birds is particularly interesting in species under strong selection pressures due to pathogenic infection. Here, by high‐throughput 16S rRNA amplicon sequencing, we characterized and compared the bacterial communities of the uropygial gland surface of three African hornbill species (Family Bucerotidae), as well as the bill and feathers of females from two of these species and the nestlings of the other one. In accordance with previous knowledge of avian microbiomes, we expected to find differences associated with species identity, age and the sampled integument. Overall, we found that: 1) the microbiome was similar among species, 2) but there were slight differences associated with the sampled body regions. Moreover, 3) we observed no consistent variation in the microbiota with age, and 4) females and nestlings sharing a nest harboured more similar gland surface microbiota compared to females and nestlings that did not share a nest. These species often reuse nest cavities, sealing them with a plug made from diverse material. Once sealed, they remain enclosed in the nest for a long period. This behaviour opens the possibility that the nest environment is key shaping the microbiota of these species and might serve as a reservoir of the sampled bacterial communities. Moreover, behavioural mechanisms such as preening may contribute to the transmission of bacteria from the uropygial gland to other body regions, enhancing bacterial similarities. This study contributes to our understanding of the role of the nest environment in structuring bacterial communities in wild birds and provides the first thorough characterization of the microbiome inhabiting different body integuments of southern African hornbills. [ABSTRACT FROM AUTHOR]

The use of cosmetic substances in communication is widespread in animals. Birds, for instance, use their uropygial secretion as a cosmetic in scenarios of sexual selection and parent-offspring communication. This secretion harbours symbiotic bacteria that could mediate the synthesis of pigments for cosmetic colouration. Here, we investigate the association between bacteria and the conspicuous yellow secretion used by spotless starling (Sturnus unicolor) nestlings to stain their mouths, and hypothesize a possible role of bacteria in the colour production. We also experimentally explore how nestling oxidizing condition influences the microbiota, suggesting that the possible bacterial-mediated coloured secretion acts as a reliable honest signal. An antioxidant supplementation experiment, previously known to affect secretion and mouth colouration, was conducted to assess its impact on the microbial community of secretions from control and experimental siblings. Antioxidant supplementation increased richness and phylogenetic diversity of the secretion's microbiota. Moreover, the microbiota's alpha and beta diversity, and the abundance of two bacterial genera (Parabacteroides and Pseudogracilibacillus), correlated with secretion colour. These findings demonstrate that antioxidant condition influences the gland microbiota of starling nestlings, and suggest a link between bacteria and the colouration of their cosmetic secretion. Alternative explanations for the detected links between bacteria and colouration are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Microscopy Research & Technique is the property of Wiley-Blackwell 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.)

As DNA sequencing technology continues to rapidly improve, studies investigating the microbial communities of host organisms (i.e., microbiota) are becoming not only more popular but also more financially accessible. Across many taxa, microbiomes can have important impacts on organismal health and fitness. To evaluate the microbial community composition of a particular microbiome, microbial DNA must be successfully extracted. Fecal samples are often easy to collect and are a good source of gut microbial DNA. Additionally, interest in the avian preen gland microbiome is rapidly growing, due to the importance of preen oil for many aspects of avian life. Microbial DNA extractions from avian fecal and preen oil samples present multiple challenges, however. Here, we describe a modified PrepMan Ultra Sample Preparation Reagent microbial DNA extraction method that is less expensive than other commonly used methodologies and is highly effective for both fecal and preen oil samples collected from a broad range of avian species. We expect our method will facilitate microbial DNA extractions from multiple avian microbiome reservoirs, which have previously proved difficult and expensive. Our method therefore increases the feasibility of future studies of avian host microbiomes. [ABSTRACT FROM AUTHOR]

The uropygial gland and the oils it produces have been shown to serve important functions in many bird species including plumage maintenance and chemical communication. Previous species comparisons of uropygial gland size have only been conducted in South American and European birds and have found little to no phylogenetic signal. Here, we document uropygial gland measurements of 34 different passerines, 1 hybrid chickadee population, and 1 Piciformes in eastern Pennsylvania, most of which are reported for the first time. Uropygial gland size is positively related to overall body size, controlling for phylogenetic relatedness. We show a significant phylogenetic signal of relative uropygial gland size and many of the species with the largest gland sizes belong to the Paridae. Overall, females show a nonsignificant but slight trend of larger relative uropygial gland sizes than males. This effect is stronger in some species than others and can also be seasonally dependent. We found no effect of relative total eggshell surface area or nest location on relative uropygial gland size. Together our results provide the first documentation of uropygial gland sizes in many of these North American species and provide interesting insight into factors influencing relative gland size including sex, season, and species. [ABSTRACT FROM AUTHOR]

Simple Summary: Feathers are essential for a bird's flight, insulation, communication, and camouflage. They degrade over time, so birds must moult regularly. This study examined how avian haemosporidian infection and the size of the uropygial gland affect feather quality and growth rate in two migratory bird species in southwestern Spain—the house martin (Delichon urbicum) and the sand martin (Riparia riparia). We found that house martins had the highest haemosporidian infection rates, likely due to their large colony size. Infection only decreased feather quality in house martins and did not affect the feather growth rate in any of the two hirundinids. Additionally, feather growth rate was positively linked to feather quality, but only in house martins. Finally, we found no connection between the uropygial gland size and feather quality or feather growth rate. These results show, for the first time, that avian haemosporidian parasites can negatively impact the feather quality of migratory birds, thus potentially affecting their flight and survival. Further research is needed to fully understand these relationships. Bird feathers have several functions, including flight, insulation, communication, and camouflage. Since feathers degrade over time, birds need to moult regularly to maintain these functions. However, environmental factors like food scarcity, stress, and parasite infections can affect feather quality and moult speed. This study examined the impact of avian haemosporidian infection and uropygial gland volume, as well as feather quality and feather growth rate in two migratory hirundine species captured in southwestern Spain—the house martin (Delichon urbicum) and sand martin (Riparia riparia). Our findings showed that the prevalence of infection varied among species, with house martins having the highest rates, possibly due to their larger colony size. Moreover, haemosporidian infection had a different impact on each species; infected house martins exhibited lower feather quality than healthy individuals, although this outcome was not observed in sand martins. Furthermore, no effect of infection on feather growth rate was observed in both hirundinids. Additionally, feather growth rate only correlated positively with feather quality in house martins. Finally, no link was observed between uropygial gland volume and feather quality or feather growth rate in any of the species in this study. These findings highlight the effect of haemosporidian infections on the plumage of migratory birds, marking, for the first time, how avian haemosporidian infection is shown to adversely impact feather quality. Even so, further research is needed to explore these relationships more deeply. [ABSTRACT FROM AUTHOR]

For a long time birds were assumed to be anosmic or at best microsmatic, with olfaction a poorly understood and seldom investigated part of avian physiology. The full viability of avian olfaction was first discovered through its functions in navigation and foraging. Subsequently, researchers have investigated the role of olfaction in different social and non‐social contexts, including reproduction, kin recognition, predator avoidance, navigation and foraging. In parallel to the recognition of the importance of olfaction for avian social behaviour, there have been advances in the techniques and methods available for the sampling and analysis of trace volatiles and odourants, leading to insights into the chemistry underlying chemical communication in birds. This review provides (i) an overview of the current state of knowledge regarding the volatile chemical composition of preen oil and feathers, its phylogenetic coverage, chemical signatures and their potential functions, and (ii) a discussion of current methods used for the isolation and detection of volatiles. Finally, lines for future research are proposed. [ABSTRACT FROM AUTHOR]

Comprehending symbiont abundance among host species is a major ecological endeavour, and the metabolic theory of ecology has been proposed to understand what constrains symbiont populations.We parameterized metabolic theory equations to investigate how bird species' body size and the body size of their feather mites relate to mite abundance according to four potential energy (uropygial gland size) and space constraints (wing area, total length of barbs and number of feather barbs). Predictions were compared with the empirical scaling of feather mite abundance across 106 passerine bird species (26,604 individual birds sampled), using phylogenetic modelling and quantile regression.Feather mite abundance was strongly constrained by host space (number of feather barbs) but not by energy. Moreover, feather mite species' body size was unrelated to the body size of their host species.We discuss the implications of our results for our understanding of the bird–feather mite system and for symbiont abundance in general. [ABSTRACT FROM AUTHOR]

Objective: This study was carried out to investigate the anatomical, morphometric, topographic, and histological features of the uropygial gland in adult male and female budgerigars (Melopsittacus undulatus). Material-Method: For this study, the uropygial glands of fourteen adult budgerigars (7 male, 7 female) were used in the study. This glandular structure located between the caudal vertebrae and pygostyle was removed by dissection. Morphological and histological characteristics of the dissected uropygial glands were determined. In addition, morphometric measurements and index calculations were performed. Tissue samples were taken to determine the histological structure of the gland, that were stained with Hematoxylin & Eosin (H&E), Masson Trichrome's and Periodic Acid Schiff-Alcian Blue. Result: In the study, it was determined that the gland structure was heart shaped and consisted of two lobes, a papilla and a draining duct system. Uropygial gland weight was determined as 1.57±0.96 g in male birds and 1.52±0.09 g in female birds. As a result of the statistical evaluation, there were significant differences between the sexes in the parameters of lobe width (p<0.05), papilla length and papilla width (p<0.01). Also, the GULI value had a statistically significant difference (p<0.05). Histological examination revealed that the gland had a two-lobed structure surrounded by a capsule composed of connective tissue. It was determined that the gland had a tubuloalveolar-holocrine structure and the epithelial layer consisted of cellular layers as germinative layer, intermediate layer, secretory layer and degenerative layer from the periphery to the centre. Conclusion: As a result of the study, it was determined that the morphological and histological structure of the uropygial gland in budgerigars showed similarities with other bird species as well as showing certain species-specific differences in general. [ABSTRACT FROM AUTHOR]

To further our knowledge of the basis of the wing-spreading behavior of cormorants, we compared the feathers of cormorants with a diving and a dabbling duck. Only the cormorant shows the division into a closed vane next to the rhachis and an open vane in the periphery of the feather. Macroscopically, the uropygial gland of the Great Cormorant (Phalacrocorax carbo) is bilobed, the papilla wears circlet feathers of type I. Histologically, the uropygial gland of the cormorant consists of tightly packed glandular tubules separated by internal septa. These tubules can be divided into three zones based on their laminar appearance. They transition into secretion-filled ducts that lead to the papilla. There is no central storage chamber. By contrast, the uropygial gland of the rock pigeon (Columba livia) contains a large central storage chamber, the glandular tissue is limited to the periphery of the gland. Thus, the histological organization of the cormorant uropygial gland is similar to many other aquatic birds. To elucidate the complex internal structure, we additionally reconstructed the uropygial gland three-dimensionally. [ABSTRACT FROM AUTHOR]

Many birds display plumage coloration and patterns that act as visual aposematic and mimetic signals for predators. Avian aposematism can also be communicated via chemical cues, where so‐called non‐host odours (NHO) emitted from the plumage, the uropygial (preen) gland or other chemical sources denote the status of birds as dangerous or unprofitable hosts for ectoparasitic and haematophagous arthropods. Avian NHO are aposematic signals that in natural concentrations repel nuisance arthropods or inhibit their attraction to hosts, as opposed to being generally unpalatable or toxic to predators. Birds that emit NHO preempt encounters with nuisance arthropods and the pathogens they transmit. Nuisance arthropods that respond to NHO avoid birds that exhibit disabling behavioural, anatomical, physiological and/or chemical defences. As with distinctive plumage patterns that evolved as visual warnings to predators, birds are selected to advertise their non‐host status to nuisance arthropods via distinctive semiochemicals. Short‐chain (C6–C10) aldehydes emitted from the plumage of some birds may act as NHO against a variety of nuisance arthropods. In some birds, the size of the uropygial gland (and presumably its secretory output) is negatively correlated with the degree of ectoparasite infestation or the incidence of malarial infection, thus implicating uropygial secretions in defence against dipteran vectors of haemosporidian pathogens. A field experiment demonstrates that volatiles emanating from the uropygial gland of the Eurasian Hoopoe Upupa epops deter some biting flies. Birds' risky habit of plucking hair from live mammals and incorporating the stolen hair tufts into their nests is hypothesized to serve as a mechanism of appropriating NHO from mammalian skin secretions for nest defence against arthropods. Feathers plucked from heterospecifics and shed snake skins that are incorporated into nests also may emit NHO. Behavioural assays measuring the repellence or attraction‐inhibition of arthropods are needed to elucidate avian NHO. Experimental efforts to elucidate the underlying defences that support avian NHO entail challenges that include the enactment of defences that are variously effective against different arthropods, and the emission of chemical signals that are variously 'understood', i.e. avoided, by different arthropods. [ABSTRACT FROM AUTHOR]

Preen gland secretions spread on the feathers contain various chemical compounds dominated by fatty acids (FAs) and volatile organic compounds (VOCs). These chemicals may significantly affect plumage condition, microbial and ectoparasitic load on feathers, and chemical communication of birds. However, how chemical composition of preen secretions varies in commercially produced chickens with respect to their genotype, sex, and feeding regime remain largely unknown, as well as the welfare implications for farmed poultry. We found that while polyunsaturated fatty acids in chicken preen secretions differed significantly with genotype (P << 0.001), saturated fatty acids and monounsaturated fatty acids varied with genotype-dependent preen gland volume (P < 0.01). Chickens of meat-type fast-growing Ross 308 genotype had reduced preen gland volume and lower proportions of all FA categories in their preen secretions compared with dual-purpose slow-growing ISA Dual chickens. A total of 34 FAs and 77 VOCs with tens of unique FAs were detected in preen secretions of both genotypes. While differences in the relative proportion of 6 of the 10 most dominant VOCs in chicken preen gland secretions were related to genotype (P < 0.001), only 1 of the 10 most dominant VOCs showed a sex effect (P < 0.01), and only 2 of the 10 most dominant VOCs showed a genotype-dependent effect of feed restriction (P < 0.05). Feed restriction had no effect on the relative proportion of any of the FAs in chicken preen gland secretions. Moreover, we found that meat-type Ross 308 preen secretions were dominated by VOCs, which are proven attractants for poultry red mite and may also increase infestation with other ectoparasites and negatively influence overall odor-mediated intraspecific communication and welfare. This study shows that no feeding management, but long-term genetic selection in commercial breeding may be the main cause of the differences in the biochemistry and function of chicken preen secretions. This might have negative consequences for chemosignaling, antiparasitic, and antimicrobial potential of preen secretions and can lead to increased susceptibility to ectoparasites, plumage care disorders, and can affect the overall condition, welfare, and productivity of commercially bred chickens. Selection-induced preen gland impairments must therefore be considered and compensated by proper management of the chicken farm and increased care about animal well-being. [ABSTRACT FROM AUTHOR]

Symbiotic bacteria on animal hosts can prevent pathogenic bacterial infections by several mechanisms. Among them, symbiotic bacteria can indirectly enhance host's immune responses or, directly, produce antimicrobial substances against pathogens. Due to differences in life-style, different host species are under different risks of microbial infections. Consequently, if symbiotic bacteria are somewhat selected by genetically determined host characteristics, we would expect the antimicrobial properties of bacterial symbionts to vary among host species and to be distributed according to risk of infection. Here we have tested this hypothesis by measuring the antimicrobial ability of the bacterial strains isolated from the uropygial-gland skin of 19 bird species differing in nesting habits, and, therefore, in risk of microbial infection. In accordance with our predictions, intensity and range of antimicrobial effects against the indicator strains assayed varied among bird species, with hole-and open-nesters showing the highest and the lowest values, respectively. Since it is broadly accepted that hole-nesters have higher risks of microbial infection than open nesters, our results suggest that the risk of infection is a strong driver of natural selection to enhance immunocompetence of animals through selecting for antibiotic-producing symbionts. Future research should focus on characterizing symbiotic bacterial communities and detecting coevolutionary processes with particular antibiotic-producing bacteria within-host species. [ABSTRACT FROM AUTHOR]

Background: Recent studies indicate that the uropygial gland produces intraspecific chemosensory cues. The jungle crow Corvus macrorhynchos, which is a type of passerine, exhibits extreme morphological variation in the gonadal gland during the breeding season. Because the uropygial gland of the jungle crow sometimes exhibits morphological changes during the breeding season, we attempted to clarify the morphological changes in the uropygial gland of the jungle crow according to development and season., Methods: Captured birds were divided into three age groups according to the color of their upper palate: <1 year, 1-2 years, and >2 years old. Paraffin sections of the uropygial gland were stained with hematoxylin and eosin, Elastica van Gieson, Giemsa, and a proliferating cell nuclear antigen antibody., Results: Sexual dimorphism was not seen in the morphology of the uropygial gland in the jungle crow. However, changes due to growth and season were identified. During the breeding season in birds>2 years old, lymphocytes formed ellipse-shaped clusters around the glandular cavity. These clusters were invaded by collagen fibers from spherical cells., Conclusions: Collagen fibers, which develop from spherical cells, seem to be related to lymphoid cluster migration. Ellipse-shaped lymphoid clusters may play a crucial role in reproductive behavior during the breeding season., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

IntroductionAvian preen oil, secreted by the uropygial gland, is an important source of volatile compounds that convey information about the sender’s identity and quality, making preen oil useful for the recognition and assessment of potential mates and rivals. Although intrinsic factors such as hormone levels, genetic background, and diet can affect preen oil volatile compound composition, many of these compounds are not the products of the animal’s own metabolic processes, but rather those of odor-producing symbiotic microbes. Social behavior affects the composition of uropygial microbial communities, as physical contact results in microbe sharing. We experimentally manipulated social interactions in captive dark-eyed juncos (Junco hyemalis) to assess the relative influence of social interactions, subspecies, and sex on uropygial gland microbial composition and the resulting preen oil odor profiles.MethodsWe captured 24 birds at Mountain Lake Biological Station in Virginia, USA, including birds from two seasonally sympatric subspecies – one resident, one migratory. We housed them in an outdoor aviary in three phases of social configurations: first in same-sex, same-subspecies flocks, then in male-female pairs, and finally in the original flocks. Using samples taken every four days of the experiment, we characterized their uropygial gland microbiome through 16S rRNA gene sequencing and their preen oil volatile compounds via GC-MS.ResultsWe predicted that if social environment was the primary driver of uropygial gland microbiome composition, and if microbiome composition in turn affected preen oil volatile profiles, then birds housed together would become more similar over time. Our results did not support this hypothesis, instead showing that sex and subspecies were stronger predictors of microbiome composition. We observed changes in volatile compounds after the birds had been housed in pairs, which disappeared after they were moved back into flocks, suggesting that hormonal changes related to breeding condition were the most important factor in these patterns.DiscussionAlthough early life social environment of nestlings and long-term social relationships have been shown to be important in shaping uropygial gland microbial communities, our study suggests that shorter-term changes in social environment do not have a strong effect on uropygial microbiomes and the resulting preen oil volatile compounds.

Avian malaria and related haemosporidian parasites can negatively impact fitness in many songbirds. Research on the malaria infection and its physiological costs on their avian hosts is heavily skewed toward native passerines, with exotic species underrepresented. However, introduced species may carry on and spread new pathogens to native species, and play a role on parasite transmission cycle in invaded bird communities as pathogen reservoir. Here, we molecularly assess the prevalence and diversity of haemosporidian parasites in three introduced wetland passerines (the Red Avadavat Amandava amandava, the Yellow-crowned Bishop Euplectes afer, and the Common Waxbill Estrilda astrild) captured during the same season in southwestern Spain. We also explored the relation between parasite infection, body condition, haematocrit, and uropygial gland volume. We detected an overall parasite prevalence of 3.55%, where Common Waxbills showed higher prevalence (6.94%) than Red Avadavats (1.51%). None Yellow-crowned Bishops were infected with haemosporidians. Almost 60% of infections were caused by Leucocytozoon, and about 40% by Plasmodium. We identified four unique lineages of Plasmodium and three of Leucocytozoon. Moreover, 91% of the identified host–parasite interactions represented new host records for these haemosporidian parasites. Parasite infection was not related to body condition, haematocrit, and uropygial gland volume of the wetland passerines. Haematocrit values varied seasonally among bird species. Additionally, haematocrit was positively related to body condition in the Yellow-crowned Bishops, but not in the other species. Red Avadavats had higher haematocrit levels than Yellow-crowned Bishops, whereas Common Waxbills showed the lower haematocrit values. The uropygial gland volume was positively correlated with body condition in all bird species. Common Waxbills showed higher uropygial gland volumes related to their body size than birds from other two species. These outcomes highlight the importance of exotic invasive species in the transmission dynamics of haemosporidian parasites.

Symbiotic bacteria on animal hosts can prevent pathogenic bacterial infections by several mechanisms. Among them, symbiotic bacteria can indirectly enhance host’s immune responses or, directly, produce antimicrobial substances against pathogens. Due to differences in life-style, different host species are under different risks of microbial infections. Consequently, if symbiotic bacteria are somewhat selected by genetically determined host characteristics, we would expect the antimicrobial properties of bacterial symbionts to vary among host species and to be distributed according to risk of infection. Here we have tested this hypothesis by measuring the antimicrobial ability of the bacterial strains isolated from the uropygial-gland skin of 19 bird species differing in nesting habits, and, therefore, in risk of microbial infection. In accordance with our predictions, intensity and range of antimicrobial effects against the indicator strains assayed varied among bird species, with hole-and open-nesters showing the highest and the lowest values, respectively. Since it is broadly accepted that hole-nesters have higher risks of microbial infection than open nesters, our results suggest that the risk of infection is a strong driver of natural selection to enhance immunocompetence of animals through selecting for antibiotic-producing symbionts. Future research should focus on characterizing symbiotic bacterial communities and detecting coevolutionary processes with particular antibiotic-producing bacteria within-host species.

BACKGROUND:The microbiome provides multiple benefits to animal hosts that can profoundly impact health and behavior. Microbiomes are well-characterized in humans and other animals in controlled settings, yet assessments of wild bird microbial communities remain vastly understudied. This is particularly true for pelagic seabirds with unique life histories that differ from terrestrial bird species. This study was designed to examine how morphological, genetic, environmental, and social factors affect the microbiome of a burrow-nesting seabird species, Leach's storm petrel (Oceanodroma leucorhoa). These seabirds are highly olfactory and may rely on microbiome-mediated odor cues during mate selection. Composition and structure of bacterial communities associated with the uropygial gland and brood patch were assessed using 16S rRNA amplicon-based Illumina Mi-Seq analysis and compared to burrow-associated bacterial communities. This is the first study to examine microbial diversity associated with multiple body sites on a seabird species. RESULTS:Results indicate that sex and skin site contribute most to bacterial community variation in Leach's storm petrels and that major histocompatibility complex (MHC) genotype may impact the composition of bacterial assemblages in males. In contrast to terrestrial birds and other animals, environmental and social interactions do not significantly influence storm petrel-associated bacterial assemblages. Thus, individual morphological and genetic influences outweighed environmental and social factors on microbiome composition. CONCLUSIONS:Contrary to observations of terrestrial birds, microbiomes of Leach's storm petrels vary most by the sex of the bird and by the body site sampled, rather than environmental surroundings or social behavior.

We performed a laboratory experiment on caged, domesticated Australian Zebra Finches (Taeniopygia guttata castanotis) to assess the effects of antimicrobial treatment applied to birds' plumage on the feather microbial loads of breeding pairs and their associated reproductive performance. Treatments included an experimental group that experienced frequent misting with a broad-spectrum antimicrobial, as well as 2 control groups. Microbial loads (colony forming units [CFUs]) sampled from the belly feathers of breeders were higher posthatching than prehatching, and experimental pairs had lower loads (one-half to one-third the CFU counts) than controls at all sampled breeding-cycle stages. Clutch size and hatching success did not differ among treatments, but experimental pairs fledged nearly 50% more offspring (mean = 3.5 per clutch) than controls (mean = 2.3 per clutch) due to experiencing much lower nestling mortality. Offspring development rate, as assessed by one metric, varied among treatments: beak color score sampled midway in the development of adult phenotype revealed that offspring of experimental pairs had more rapid development. Findings imply that experimentally reduced density of feather microbial loads on breeders decreased reproductive costs in the posthatch phase, resulting in increased offspring survival and condition. At the time offspring fledged, uropygial gland volume tended to be greater among breeders that had experienced antimicrobial application throughout the breeding cycle. These results are consistent with a growing literature showing that the feather microbiome contributes significantly to the evolution of avian life histories and behavior and indicate that Zebra Finches are a useful laboratory model for investigating in vivo effects of the feather microbiome on avian hosts. [ABSTRACT FROM AUTHOR]

Abstract Background Extra-pair paternity (EPP) in birds provides benefits in terms of more offspring, and characteristics for maintenance of this behaviour have been the subject of investigation. Microorganisms are known to be transmitted during mating, especially when mating with multiple partners, and factors reducing this cost of multiple mating are expected. Further, plumage brightness and colour intensity have been shown to be important traits to benefits from multiple mating as predicted by sexual selection. The aim of this study was to investigate the relationship between the rate of extra-pair paternity and the relative size of the uropygial gland at the interspecific level, as the uropygial gland is an exocrine gland hypothesized to produce antiparasitic substances and further identified to affect plumage brightness. Because of the expected benefits of large uropygial gland in scenarios of sexual selection, we predicted a positive correlation with EPP. Methods We collected information from the literature of uropygial gland size and frequency of extra-pair paternity of 60 avian species of different families and explored the predicted positive correlation between them. We did so with means of comparative analyses that considered phylogenetic relationship as random factor and included body mass as covariate. We used Markov chain Monte Carlo generalized linear mixed models that were weighted by number of nests used to estimate extra-pair paternity. Results We detected a positive relationship between level of extra-pair paternity and uropygial gland size at an interspecific level. This finding is consistent with the prediction. Conclusions We discuss the importance of this result in scenarios of sexual selection and argue that the detected relationship may have arisen by utilizing antiparasitic secretions through secondary sexual characters indicating parasite resistance.

Acoustic and visual signals are well known to play important roles in social communication in birds. Growing evidence suggests that many bird species, including species of songbirds, additionally have a well-developed sense of smell. However, we are still at the beginning of understanding the potential importance of chemical communication in the social lives of birds, for example in mate choice. The secretion of the preen gland may be an important contributor to the chemical phenotype of birds. Here, we report on a first characterisation of the chemical composition of the preen gland secretion of the Blue Tit (Cyanistes caeruleus), a common songbird which is an often used model species in animal behaviour and ecology, in particular also in studies of sexual selection and (extra-pair) mate choice. We found sex differences in the composition of the preen gland secretion in breeding Blue Tits. Females further tended to have a larger number of putative compounds in their secretions compared to males. We briefly discuss the possible implications of these findings and speculate that the chemical composition of the preen gland secretion may be a sexually selected trait in Blue Tits. Our preliminary findings warrant follow-up research into the patterns of within- and among individual variation in the chemical composition of the preen gland secretion as well as the identification of the main chemical compounds involved. [ABSTRACT FROM AUTHOR]

Metabolites produced by symbiotic microbes can affect the odour of their hosts, providing olfactory cues of identity, sex or other salient features.In birds, preen oil is a major source of body odour that differs between populations and sexes. We hypothesized that population and sex differences in preen oil chemistry reflect underlying differences in preen gland microbiota, predicting that these microbes also differ among populations and between the sexes. We further predicted that pairwise similarity in the community composition of preen gland microbiota would covary with that of preen oil chemical composition, consistent with the fermentation hypothesis for chemical recognition.We analysed preen oil chemistry and preen gland bacterial communities of song sparrows Melospiza melodia. Birds were sampled at sites for which population and sex differences in preen oil have been reported, and at a third site that has been less studied.Consistent with prior work in this system, we found population and sex differences in preen oil chemistry. By contrast, we found population differences but not sex differences in the community composition of preen gland microbes. Overall similarity in the community composition of preen gland microbiota did not significantly covary with that of preen oil chemistry. However, we identified a subset of six microbial genera that maximally correlated with preen oil composition.Although both preen gland microbiota and preen oil composition differ across populations, we did not observe an overall association between them that would implicate symbiotic microbes in mediating variation in olfactory cues associated with preen oil. Instead, certain subsets of microbes may be involved in mediating olfactory cues in birds, but experiments are required to test this. [ABSTRACT FROM AUTHOR]

Abstract Many waterbirds have fully (totipalmate) or partially webbed (palmate) feet that are used for locomotion in aquatic environments. If webbed feet and wings both contribute to efficient diving, we predicted a positive association between the area of webbed feet and the size of the frontal locomotor apparatus (wing area, heart mass, and breast muscle, after adjusting for any partial effects of body size). We predicted that individuals able to acquire more and better quality food due to larger webbed feet should have larger livers with higher concentrations of fat‐soluble antioxidants such as vitamin E, and invest more in immune function as reflected by the relative size of the uropygial gland than individuals with small webbed feet. Here, we examine if the area of webbed feet is correlated with locomotion, diet, and body condition in a sea‐duck, the eider (Somateria mollissima). We analyzed an extensive database of 233 eiders shot in Danish waters and at Åland, Finland during winter and early spring. Eiders with larger webbed feet had a larger locomotor apparatus, but did not have larger body size, they had larger uropygial glands that waterproof the plumage, they had larger beak volume and larger gizzards, and they had higher body condition. These findings imply that eiders with large webbed feet benefitted in terms of locomotion, feeding, and reproduction.

Abstract Background The uropygial gland is an exocrine gland located above the tail of birds that produces a diverse range of biochemicals. It has been hypothesized to be involved in chemical protection, water-proofing and maintenance of plumage brightness. Although these not necessarily mutually exclusive functions have received some empirical support, there has been little empirical research on the function of water-proofing. Methods Here we analyzed data for 229 individual eiders (Somateria mollissima) collected by Danish hunters during 2016‒2018. Results The Eider is a sea-duck that spends almost its entire life in sea water emphasizing water-proofing of the plumage. The size of the uropygial gland increased with body mass in males, but not in females, and it increased with age. The size of the uropygial gland decreased during winter. Eiders with small uropygial glands grew their feathers at a fast rate. Eiders with large wing areas had large uropygial glands. Conclusions These findings are consistent with large uropygial glands playing a role in water-proofing during molt and foraging, but also that uropygial glands may play a role in chemical defense.

We describe the morphological, histological and histochemical characteristics of the uropygial gland of the duck (Anas platyrhynchos) and pigeon (Columba livia). The weight and dimensions of the glands were recorded. The gland openings onto the papilla in ducks were surrounded by double tufts of downy feathers; the tufts were held together by an oily secretion. In the pigeon, the gland opening was onto naked skin. Samples for light and transmission electron microscopy were obtained from adult birds. Gland morphometry of the duck showed greater dimensions and relative gland weight than the pigeon. In both species the gland was lined by stratified epithelium, packed with secretary tubules and filled with oil droplets that were discharged into a central cavity. In the pigeon, the gland was branched and alveolar with a wide central lumen, whereas in the duck it was simple and branched tubular. Ultrastructural analysis of both species revealed that the fat globules tended to condense in the peripheral layers of the secretory and degenerative cells, and the nuclei exhibited pyknosis, which suggest the holocrine nature of the gland. Morphometric and histological analysis of the gland showed that the architecture is similar among birds; however, some species-specific differences suggest a functional correlation with the habitat. [ABSTRACT FROM AUTHOR]

The exchange of information between animals is crucial for maintaining social relations, individual survival, and reproduction, etc. The uropygial gland is a particular secretion gland found in birds. We speculated that uropygial gland secretions might act as a chemical signal responsible for sexual communication. We employed non-targeted metabolomic technology through liquid chromatography and mass spectrometry (LC-MS) to identifying duck uropygial gland secretions. We observed 11,311 and 14,321 chemical substances in the uropygial gland secretion for positive and negative ion modes, respectively. Based on their relative contents, principal component analysis (PCA) showed that gender significantly affects the metabolite composition of the duck uropygial gland. A total of 3831 and 4510 differential metabolites were further identified between the two sexes at the positive and negative ion modes, respectively. Of them, 139 differential metabolites were finally annotated. Among the 80 differential metabolites that reached an extremely significant difference (p < 0.01), we identified 24 volatile substances. Moreover, we further demonstrated that five kinds of volatile substances are highly repeatable in all testing ducks, including picolinic acid, 3-Hydroxypicolinic acid, indoleacetaldehyde, 3-hydroxymethylglutaric acid, and 3-methyl-2-oxovaleric acid. All these substances are significantly higher in males than in females, and their functions are involved in the reproduction processes of birds. Our data implied that these volatile substances act as sex pheromones and may be crucial olfactory clues for mate selection between birds. Our findings laid the foundation for future research on whether uropygial gland secretion can affect ducks’ reproduction and production.

Much of the growing interest in avian chemical signals has focused on the role of kin recognition or mate attraction, often with an emphasis on males, with uropygial gland secretions perhaps providing information about an individual's identity and quality. Yet, data collected to date suggest sexual dimorphism in uropygial glands and secretions are often emphasized in female, rather than in male birds. That is, when a sexual difference occurs (often during the breeding season only), it is the female that typically exhibits one of three patterns: (1) a larger uropygial gland, (2) a greater abundance of volatile or semi-volatile preen oil compounds and/or (3) greater diversity of preen oil compounds or associated microbes. These patterns fit a majority of birds studied to date (23 of 30 chemically dimorphic species exhibit a female emphasis). Multiple species that do not fit are confounded by a lack of data for seasonal effects or proper quantitative measures of chemical compounds. We propose several social functions for these secretions in female-based patterns, similar to those reported in mammals, but which are largely unstudied in birds. These include: (1) intersexual advertisement of female receptivity or quality, including priming effects on male physiology, (2) intrasexual competition, including scent marking and reproductive suppression or (3) parental behaviors, such as parent-offspring recognition and chemical protection of eggs and nestlings. Revisiting the gaps of chemical studies to quantify the existence of female social chemosignals and any fitness benefit(s) during breeding are potentially fruitful but overlooked areas of future research. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated that preen oil acts to reduce or eliminate feather‐associated bacteria. The mechanisms underlying this antibacterial activity, however, are incompletely understood. In addition to the activity of alcohols (i.e. 3,7‐dimethyloctan‐1‐ol), recent research has suggested that antimicrobial peptides may underlie the antibacterial activity of preen oil. Here, we document the presence of innate and adaptive immune proteins, lysozyme and immunoglobulin Y (IgY), in the preen oil of house sparrows Passer domesticus. We suggest lysozyme functions as an antimicrobial agent, with potentially important impacts against Gram‐positive feather degrading bacteria. Furthermore, both lysozyme and IgY likely act in local immune defence of the preen gland, and may also play a role in regulating the local microbiome, with potentially important consequences for chemical communication and signalling. Our findings suggest that the preen gland and its secretions should be considered an integral part of the body's first line of defence against invading infections. [ABSTRACT FROM AUTHOR]

Mercury is a global pollutant and potent neurotoxic metal. Its most toxic and bioavailable form, methylmercury, can have both lethal and sublethal effects on wildlife. In birds, methylmercury exposure can disrupt behavior, hormones, the neuroendocrine system, and feather integrity. Lipid-rich tissues and secretions may be particularly susceptible to disruption by lipophilic contaminants such as methylmercury. One such substance is feather preen oil, a waxy secretion of the uropygial gland that serves multiple functions including feather maintenance, anti-parasitic defense, and chemical signaling. If methylmercury exposure alters preen oil composition, it could have cascading effects on feather quality, susceptibility to ectoparasites, and mate choice and other social behaviors. We investigated whether exposure to methylmercury, either alone or in association with other stressors, affects preen oil chemical composition. We used a two-factor design to expose adult song sparrows (Melospiza melodia) to an environmentally relevant dietary dose of methylmercury and/or to another stressor (unpredictable food supply) for eight weeks. The wax ester composition of preen oil changed significantly over the 8-week experimental period. This change was more pronounced in the unpredictable food treatment, regardless of dietary methylmercury. Contrary to our prediction, we found no main effect of methylmercury exposure on preen oil composition, nor did methylmercury interact with unpredictable food supply in predicting the magnitude of chemical shifts in preen oil. While it remains critical to study sublethal effects of methylmercury on wildlife, our findings suggest that the wax ester composition of preen oil is robust to environmentally relevant doses of this contaminant. [ABSTRACT FROM AUTHOR]

The present experiment was conducted to evaluate the effect of uropygialectomy on Productive Characteristics and carcass parameters of Japanese Quails Coturnix coturnix Japonica. A total of 540, one day old quails (360 females, 180 males) were randomly distributed in to two treatment groups with 3 replicates for each. Chicks in T1 used as control, while chicks in T2 were subjected to the uropygialectomy which was done at the second day of age. All chicks were fed on standard starter diet for the first three weeks and then fed on finisher diet through out of the experimental period which was lasted for six weeks .Weekly body weight, feed consumption, feed conversion were recorded. At the end of experimental period, three male and three female from each replicate treatment were scarified and dressing percentages, carcass cuts and giblets weight were measured. The data showed that Uropygialctomy cause significant (P<0.05) improvement in some productive characteristics including the weekly body weight gaine, marketing weight, feed consumption and feed conversion ratio, .Treatment were significantly (P<0.05) increased dressing percentage, weight of carcase back but had no effect in the weight of breast, thigh, drumstick wings and neck. Eatable gieblet (heart, liver and gizzard) weight were not significantly affected by treatment. It can be concluded that uropygialectomy were significantly improved all production performance characteristics of Japanese quails. [ABSTRACT FROM AUTHOR]

Avian plumage harbors various pathogens such as feather-degrading bacteria, which have the potential to reduce host fitness. A growing body of evidence suggests that the secretion of the uropygial gland of birds—preen oil—acts as one of the first lines of defence against harmful bacteria. However, previous studies on the antimicrobial impact of preen oil have yielded controversial results. The impact of preen oil on bacterial densities of feathers was experimentally investigated in two passerine species: great tits Parus major and pied flycatchers Ficedula hypoleuca. More specifically, we tested whether the antibacterial effect of the preen oil secreted by the same individual differs from that of the preen oil originating from the gland of other species. In the laboratory, ventral feathers were treated with preen oil from (1) an individual's own gland, (2) from the gland of another passerine species, or (3) from the gland of a phylogenetically distant bird species. We detected a significant antibacterial effect of preen oil on bacteria that were attached to feathers, though the effect did not depend on whether the oil originated from the individual's own gland or from the gland of another bird species. However, treatment with preen oil suppressed the density of bacteria more in the pied flycatcher than in the great tit. This is the first study providing experimental evidence that preen oil represents an important antimicrobial mechanism against those plumage bacteria that are attached to feathers. [ABSTRACT FROM AUTHOR]

A 33-year-old male blue and gold macaw (Ara ararauna) presented with a 5-month history of an ulcerated lesion and feather loss at the tail base. Two 4-mm biopsies obtained by the primary care veterinarian were consistent with uropygial gland adenocarcinoma. The bird was examined at the Veterinary Medical Teaching Hospital, University of California, and on physical evaluation, the dorsal and ventral surface of the tail base were devoid of feathers, ulcerated and crusted without an identifiable uropygial gland. Complete blood count, plasma biochemistry panel, whole-body radiographs, and an echocardiogram were performed before surgery. The bird was anesthetized, and a complete amputation of the tail was performed. The skin was incised with a radiofrequency electrosurgical system approximately 2 mm circumferentially cranial to the diseased tissue. The musculature was transected to the level of the vertebral column, disarticulating between the second and third caudal vertebrae and transecting the spinal cord with a no. 15 blade. Lateral vertebral processes of the second vertebra were removed with a rongeur. Coccygeus lateralis muscles and tensor fasciae latae muscles and skin were closed laterolaterally with 2 layers and 3-0 polydioxanone suture. The bird recovered uneventfully and was discharged after 6 days of hospitalization. The histopathological diagnosis was adenocarcinoma with squamous differentiation, marked scirrhous response, and superficial epithelial ulceration. It was determined that narrow margins of unaffected tissue were achieved from the pathological examination of submitted material. The bird was evaluated 24 days after surgery and again 3.5 months after surgery, without evidence of complications or recurrence. Approximately 10 days after the last reexamination, the bird was euthanatized after being found minimally responsive at home. A postmortem examination was not performed. [ABSTRACT FROM AUTHOR]

Abstract Background The microbiome provides multiple benefits to animal hosts that can profoundly impact health and behavior. Microbiomes are well-characterized in humans and other animals in controlled settings, yet assessments of wild bird microbial communities remain vastly understudied. This is particularly true for pelagic seabirds with unique life histories that differ from terrestrial bird species. This study was designed to examine how morphological, genetic, environmental, and social factors affect the microbiome of a burrow-nesting seabird species, Leach’s storm petrel (Oceanodroma leucorhoa). These seabirds are highly olfactory and may rely on microbiome-mediated odor cues during mate selection. Composition and structure of bacterial communities associated with the uropygial gland and brood patch were assessed using 16S rRNA amplicon-based Illumina Mi-Seq analysis and compared to burrow-associated bacterial communities. This is the first study to examine microbial diversity associated with multiple body sites on a seabird species. Results Results indicate that sex and skin site contribute most to bacterial community variation in Leach’s storm petrels and that major histocompatibility complex (MHC) genotype may impact the composition of bacterial assemblages in males. In contrast to terrestrial birds and other animals, environmental and social interactions do not significantly influence storm petrel-associated bacterial assemblages. Thus, individual morphological and genetic influences outweighed environmental and social factors on microbiome composition. Conclusions Contrary to observations of terrestrial birds, microbiomes of Leach’s storm petrels vary most by the sex of the bird and by the body site sampled, rather than environmental surroundings or social behavior.

A five-year-old female cockatiel weighing 117 g was presented with a fast-growing mass beside the uropygial gland. Excisional biopsy was performed and the mass measured 5 × 3. 5 × 4 cm in size and weighed 30.6 g. On the surface of cut sections, the mass was yellow-brown with white or yellow colloidal substances and red exudate. Histopathology showed that the tumor mass was covered by the skin and located in the deep dermis and hypodermis. The tumor consisted of abundant vascular adipose tissue and lipoblasts with intracytoplasmic lipid droplets, which varied in size. Also, small, well-differentiated blood vessels, with varied degrees of congestion and dilation, were observed within the tumor. Histochemically, staining with Oil red O produced a positive reaction in which the lipid droplets presented a reddish color. Immunohistochemistry produced positive staining for Desmin and successfully marked the muscular layers of blood vessels. On the basis of these results, a rare case of liposarcoma with microvascular proliferation adjacent to the uropygial gland was diagnosed in a cockatiel. [ABSTRACT FROM AUTHOR]

Many waterbirds have fully (totipalmate) or partially webbed (palmate) feet that are used for locomotion in aquatic environments.If webbed feet and wings both contribute to efficient diving, we predicted a positive association between the area of webbed feet and the size of the frontal locomotor apparatus (wing area, heart mass, and breast muscle, after adjusting for any partial effects of body size). We predicted that individuals able to acquire more and better quality food due to larger webbed feet should have larger livers with higher concentrations of fat‐soluble antioxidants such as vitamin E, and invest more in immune function as reflected by the relative size of the uropygial gland than individuals with small webbed feet.Here, we examine if the area of webbed feet is correlated with locomotion, diet, and body condition in a sea‐duck, the eider (Somateria mollissima). We analyzed an extensive database of 233 eiders shot in Danish waters and at Åland, Finland during winter and early spring.Eiders with larger webbed feet had a larger locomotor apparatus, but did not have larger body size, they had larger uropygial glands that waterproof the plumage, they had larger beak volume and larger gizzards, and they had higher body condition.These findings imply that eiders with large webbed feet benefitted in terms of locomotion, feeding, and reproduction. [ABSTRACT FROM AUTHOR]

The uropygial gland has been hypothesized to play a role in sexual signaling through a "make-up" function derived from the effects of secretions from the gland on the appearance of the plumage and bare parts of the body. Here we show that plumage brightness of dorsal feathers of individual barn swallows Hirundo rustica was greater in mated than in unmated individuals. In addition, plumage brightness increased with colony size. Furthermore, plumage brightness was positively correlated with the amount of wax in the uropygial gland, negatively correlated with time of sampling of uropygial wax (perhaps because more wax is present early in the morning after an entire night of wax production without any preening), and negatively correlated with the number of chewing lice that degrade the plumage. Experimentally preventing barn swallows from access to the uropygial gland reduced plumage brightness, showing a causal link between secretions from the uropygial gland and plumage brightness. These findings provide evidence consistent with a role of uropygial secretions in signaling plumage brightness. [ABSTRACT FROM AUTHOR]

A 12-year-old female cockatiel (Nymphicus hollandicus) was presented with a squamous cell carcinoma involving the uropygial gland. Electrochemotherapy (ECT) as a minimally invasive treatment option was applied. The patient was anesthetized, a chemotherapeutic agent was injected intratumorally, and electrical pulses were delivered using plate and needle electrodes. In the first session of ECT cisplatin was used, and no change in tumor volume was observed during the following month. In a further 2 treatments 1 month apart, bleomycin was used. The tumor responded, and the mass became necrotic and eventually disappeared. Unfortunately, the tumorous mass reappeared after 3 months. Therefore, a fourth ECT using bleomycin was performed and the tumor completely regressed. No tumor growth was seen in 18 months after the last therapy. This report presents the clinical significance of ECT using cisplatin and bleomycin in treatment of uropygial gland squamous cell carcinoma in a cockatiel. [ABSTRACT FROM AUTHOR]

Abstract Although birds are hosts to a large number of microorganisms, microbes have rarely been found in avian oil glands. Here, we report on two strains of a new bacterial species from the preen oil of American barn owls (Tyto furcata). Phenotypic as well as genotypic methods placed the isolates to the genus Kocuria. Strains are non-fastidious, non-lipophilic Gram-positive cocci and can be unambiguously discriminated from their closest relative Kocuria rhizophila DSM 11926T. In phylogenetic trees, the owl bacteria formed a distinct cluster which was clearly separated from all other known Kocuria species. The same conclusion was drawn from MALDI-TOF MS analyses. Once again, the new bacterial strains were very similar to one another, but exhibited substantial differences when compared to the most closely related species. Besides, the results of the biochemical tests, optimum growth conditions and pigmentation differed from closely related Kocuria spp. Finally, ANIb values of less than 87% provided striking evidence that the isolates recovered from American barn owls represent a hitherto undescribed species, for which we propose the name Kocuria tytonicola sp. nov. The type strain is 489T (DSM 104133T = LMG 29945T, taxonumber TA00340). [ABSTRACT FROM AUTHOR]

To increase fitness, a wide range of vertebrates preferentially mate with partners that are dissimilar at the major histocompatibility complex (MHC) or that have high MHC diversity. Although MHC often can be assessed through olfactory cues, the mechanism by which MHC genes influence odour remains largely unclear. MHC class IIB molecules, which enable recognition and elimination of extracellular bacteria, have been suggested to influence odour indirectly by shaping odour‐producing microbiota, i.e. bacterial communities. However, there is little evidence of the predicted covariation between an animal's MHC genotype and its bacterial communities in scent‐producing body surfaces. Here, using high‐throughput sequencing, we tested the covariation between MHC class IIB genotypes and feather microbiota in the blue petrel (Halobaena caerulea), a seabird with highly developed olfaction that has been suggested to rely on oduor cues during an MHC‐based mate choice. First, we show that individuals with similar MHC class IIB profiles also have similar bacterial assemblages in their feathers. Then, we show that individuals with high MHC diversity have less diverse feather microbiota and also a reduced abundance of a bacterium of the genus Arsenophonus, a genus in which some species are symbionts of avian ectoparasites. Our results, showing that feather microbiota covary with MHC, are consistent with the hypothesis that individual MHC genotype may shape the semiochemical‐producing microbiota in birds. [ABSTRACT FROM AUTHOR]

Nest bacterial environment influences avian reproduction directly because it might include pathogenic- or antibiotic-producing bacteria or indirectly because predators or ectoparasites can use volatile compounds from nest bacterial metabolism to detect nests of their avian hosts. Hoopoes (Upupa epops) do not build nests. They rather reuse holes or nest-boxes that contain remains of nest-materials from previous breeding seasons. Interestingly, it has been recently described that the nest’s bacterial environment partly affects the uropygial gland microbiota of hoopoe females and eggshells. Blood-sucking ectoparasites use chemical cues to find host nests, so we experimentally tested the hypothetical effects of microorganisms inhabiting nest-material remains before reproduction regarding the intensity of ectoparasitism suffered by 8-day-old nestling hoopoes. In accordance with the hypothesis, nestlings hatched in nest-boxes with autoclaved nest-material remains from the previous reproductive seasons suffered less from ectoparasites than those hatched in the control nest-boxes with nonautoclaved nest-material. Moreover, we found a positive association between the bacterial density of nest-material during the nestling phase and ectoparasitism intensity that was only apparent in nest-boxes with autoclaved nest-material. However, contrary to our expectations, nest bacterial load was positively associated with fledgling success. These results suggest a link between the community of microorganisms of nest-material remains and the intensity of ectoparasitism, and, on the other hand, that the nest bacterial environment during reproduction is related to fledging success. Here, we discuss possible mechanisms explaining the experimental and correlative results, including the possibility that the experimental autoclaving of nest material affected the microbiota of females and nestlings’ secretion and/or nest volatiles that attracted ectoparasites, therefore indirectly affecting both the nest bacterial environment at the nestling stage and fledging success.

Chemical signaling has been well studied in invertebrates and mammals but less so in birds, due to the longstanding misconception that olfaction is unimportant or even non-existent in this taxon. However, recent findings suggest that olfaction plays an important role in avian mate choice and reproductive behavior, similar to other taxa. The leading candidate source for compounds involved in avian chemical communication is preen oil, a complex mixture secreted from the uropygial gland. Preen oil contains volatile compounds and their potential wax ester precursors, and may act as a reproductive chemosignal. Reproductive signals are generally sexually dimorphic, age-specific, seasonally variable, and may also vary geographically. We tested whether preen oil meets these expectations by using gas chromatography to examine the wax ester composition of preen oil in song sparrows (Melospiza melodia). We found that the wax ester composition of preen oil was significantly different between sexes, age classes, seasons, and populations. Collectively, our results suggest that song sparrow preen oil meets the criteria of a chemical cue that may influence mate choice and reproduction. Our findings in song sparrows, which are sexually monomorphic in plumage, also parallel patterns described for dark-eyed juncos (Junco hyemalis), a closely related songbird with sexually dimorphic plumage. Behavioral tests are needed to confirm that song sparrows attend to the cues present in preen oil, but our findings support the increasingly accepted idea that chemical communication is common and widespread in birds as it is in other taxa. [ABSTRACT FROM AUTHOR]

Abstract Two strains (pedersoliT and girotti) of a new species of bacteria were isolated from the preen glands of wild Egyptian geese (Alopochen aegyptiacus) from the river Neckar in southern Germany in two subsequent years. The strains were lipophilic, fastidious, Gram-positive rods and belonged to the genus Corynebacterium. Phylogenetically, the isolates were most closely related to Corynebacterium falsenii DSM 44353T which has been found to be associated with birds before. 16S rRNA gene sequence similarity to all known Corynebacterium spp. was significantly <97%. Corresponding values of rpoB showed low levels of similarity <87% and ANIb was <73%. G + C content of the genomic DNA was 65.0 mol% for the type strain of the goose isolates, as opposed to 63.2 mol% in Corynebacterium falsenii. MALDI-TOF MS analysis of the whole-cell proteins revealed patterns clearly different from the related species, as did biochemical tests, and polar lipid profiles. We therefore conclude that the avian isolates constitute strains of a new species, for which the name Corynebacterium heidelbergense sp. nov. is proposed. The type strain is pedersoliT (=DSM 104638T = LMG 30044T). [ABSTRACT FROM AUTHOR]

Situated at high positions on marine food webs, seabirds accumulate high concentrations of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), and hexachlorocyclohexanes (HCHs). Our previous studies proposed the usefulness of seabirds preen gland oil as a nondestructive biomonitoring tool. The present study applied this approach to 154 adult birds of 24 species collected from 11 locations during 2005-2016 to demonstrate the utility of preen gland oil as a tool for global monitoring POPs, i.e., PCBs, DDTs, and HCHs. Concentrations of the POPs were higher in the Northern Hemisphere than in the Southern Hemisphere. In particular, ∑20PCBs and∑DDTs were highly concentrated in European shags (Phalacrocorax aristotelis) and Japanese cormorants (Phalacrocorax capillatus), explainable by a diet of benthic fishes. Higher concentrations of γ-HCH were detected in species from the polar regions, possibly reflecting the recent exposure and global distillation of ∑HCHs. We examined the relationship between age and POP concentrations in preen gland oil from 20 male European shags, aged 3-16 years old. Concentrations and compositions of POPs were not related to age. We also examined sex differences in the POP concentrations from 24 streaked shearwaters (Calonectris leucomelas) and did not detect a sex bias. These results underline the importance of the geographic concentration patterns and the dietary behavior as determinants species-specific POPs concentrations in preen gland oil. [ABSTRACT FROM AUTHOR]