Search results for "Plumage"
showing 10 items of 29 documents
Curse of the black spot: spotting negatively correlates with fitness in black grouseLyrurus tetrix
2016
There is growing evidence that achromatic plumage can act as honest indicators of male quality. In some species with areas of white plumage, black melanin spots can be found on parts of the feathers. The functional significance of these spots and the relationship with male quality is yet poorly understood. We investigated the relationship between black melanin spots in an otherwise totally white ornament, the undertail covert, in relation to age, fitness and covariance with past and present expression of sexual traits, in the lekking black grouse Lyrurus tetrix. We found that spots at tips of feathers (tip spots) were negatively related to survival and reproductive success, and covaried neg…
Gray plumage color is more cryptic than brown in snowy landscapes in a resident color polymorphic bird
2020
Abstract Camouflage may promote fitness of given phenotypes in different environments. The tawny owl (Strix aluco) is a color polymorphic species with a gray and brown morph resident in the Western Palearctic. A strong selection pressure against the brown morph during snowy and cold winters has been documented earlier, but the selection mechanisms remain unresolved. Here, we hypothesize that selection favors the gray morph because it is better camouflaged against predators and mobbers in snowy conditions compared to the brown one. We conducted an online citizen science experiment where volunteers were asked to locate a gray or a brown tawny owl specimen from pictures taken in snowy and snow…
Elevated oxidative stress in pied flycatcher nestlings of eumelanic foster fathers under low rearing temperatures
2019
Striking variation in melanin coloration within natural populations is likely due to the different fitness outcomes of alternative phenotypes in varying environmental conditions. There are two types of melanin: eumelanins yield blackish hues, whereas pheomelanins yield reddish hues. The production of eumelanins requires low levels of glutathione (GSH), which is the most important intracellular antioxidant, whereas the production of pheomelanins requires high levels of GSH. We investigated the oxidative status of male pied flycatchers (Ficedula hypoleuca) with different degrees of melanin coloration under different temperatures during the nestling period. Moreover, we assessed the oxidative …
Sex-ratio and male sexual characters in a population of Blue tits Parus caeruleus
2005
Sex allocation theory proposes that parents should bias the sex ratio of their offspring if the reproductive value of one sex is greater than that of the other. In the monogamous blue tit (Parus caeruleus), males have a greater variance in reproductive success than females, and high-quality males have higher reproductive success than high-quality females due to extrapair paternity. Consequently, females mating with attractive males are expected to produce broods biased toward sons, as sons benefit more than daughters from inheriting their father’s characteristics. Song and plumage color in birds are secondary sexual characters indicating male quality and involved in female choice. We used t…
Iridescent structurally based coloration of eyespots correlates with mating success in the peacock.
2007
Gaudy plumage coloration is a widespread ornamental trait in birds and thought to be sexually selected. Although much attention has been devoted to structural coloration reflecting in UV, the signaling function of structural colors lacking UV reflectance and those that exhibit iridescence coloration are poorly documented. The train of the peacock (Pavo cristatus), a classical example of a sexually selected trait, is composed of iridescent structurally colored eyespots not reflecting in UV. Until today, the role played by the structural color of the eyespots in female mate choice has never been investigated using spectrometry. We measured eyespot coloration from a stationary angle (static co…
Seasonal changes in some thermoregulatory variables of the house sparrow (Passer domesticus L.)
1975
Abstract 1. The body weight, plumage, insulation, oxygen consumption and body lipids were studied seasonally in the house sparrow, Passer domesticus L. 2. The weights of body and plumage were greater in autumn and winter than in summer. 3. The insulative property of the plumage was better in autumn and winter birds than in summer birds. 4. The oxygen consumption of young birds was higher than that of plucked and adult birds. 5. The amount of subcutaneous depot fat tissue and its lipid content was greatest in autumn. The C18-unsaturated fatty acids were most prominent in the subcutaneous fat. Palmitic acid was the most prevalent fatty acid in the liver. The relative amount of C18-unsaturated…
Sexing adult Cory's Shearwater by discriminant analysis of body measurements on Linosa Island (Sicilian Channel), Italy
2001
-Males and females of many avian species may show no plumage dimorphism, but often can be sexed by differences in body measurements. Sex determination of many Cory's Shearwaters Calonectris diomedea, was possible by multiplying bill length by bill depth. In this study, discriminant analysis of six measurements (bill length, bill depth, wing, tail, tarsus and mass) was performed on Cory's Shearwaters breeding on Linosa Island (Sicilian Channel), Italy and the efficiency of sex determination was compared with the univariate method. Results show the advantages of the discriminant functions. Bill depth is the best parameter (up to 92% correct classification), followed by mass (84% correct class…
Genome-Wide Analyses Identifies Known and New Markers Responsible of Chicken Plumage Color
2020
Simple Summary In order to assess sources of variation related to Polverara breed plumage color (black vs. white), we carried out genome-wide analyses to identify the genomic regions involved in this trait. The present work has revealed new candidate genes involved in the phenotypic variability in local chicken populations. These results also contribute insights into the genetic basis for plumage color in poultry, and confirm the great complexity of the mechanisms that control this trait. Abstract Through the development of the high-throughput genotyping arrays, molecular markers and genes related to phenotypic traits have been identified in livestock species. In poultry, plumage color is a…
Ultraviolet reflection and female mate choice in the pied flycatcher, Ficedula hypoleuca
2002
In pied flycatchers females seem to prefer male territory quality rather than male characteristics, and the results of female mate choice experiments are divergent. In this outdoor aviary study, we examined how altering the ultraviolet reflection of males affects female mate choice behaviour. We chose pairs of males with similar human-visible dorsal colour and morphological traits. We then reduced the proportional ultraviolet reflectance in one male with sunscreen chemicals. The other male was treated with a chemical that slightly increased the ultraviolet reflectance of the plumage. In the experiment females clearly preferred males with slightly increased ultraviolet reflection. Our result…
Carry-over effects of conditions at the wintering grounds on breeding plumage signals in a migratory bird : roles of phenotypic plasticity and select…
2016
To understand the consequences of ever-changing environment on the dynamics of phenotypic traits, distinguishing between selection processes and individual plasticity is crucial. We examined individual consistency/plasticity in several male secondary sexual traits expressed during the breeding season (white wing and forehead patch size, UV reflectance of white wing patch and dorsal melanin coloration) in a migratory pied flycatcher (Ficedula hypoleuca) population over an 11-year period. Furthermore, we studied carry-over effects of three environmental variables (NAO, a climatic index; NDVI, a vegetation index; and rainfall) at the wintering grounds (during prebreeding moult) on the expressi…