Nests are important structures for birds to raise their offspring and for signaling.Many birds incorporate feathers into the nest,since feathers were traditionally thought to serve the function of insulation.Hypothese...Nests are important structures for birds to raise their offspring and for signaling.Many birds incorporate feathers into the nest,since feathers were traditionally thought to serve the function of insulation.Hypotheses in recent years have considered that some birds place feathers in conspicuous locations in the nest for decoration to trigger a fear response in the competitors.In this study,we investigated whether decorative feathers could deter nest usurpation by Crested Mynas(Acridotheres cristatellus)by manipulating nest box contents.The results revealed that Crested Mynas preferred black feathers to white feathers as decorations and occupied nest boxes decorated with black feathers significantly less than those decorated with white feathers,suggesting that black decorative feathers in the nest could be more effective in preventing nest usurpation by Crested Mynas and that white decorative feathers may have other functions.The black feathers in the nest are prominently placed at the edge of the nest to convey the message that“this nest is occupied”or“the owner of this nest has been preyed upon”to visitor Crested Mynas,thus effectively preventing them from usurping the nest at a later stage.展开更多
Background: Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss...Background: Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss at other times of the year and its fitness consequences remain poorly known.Methods: I used information on the number and the mass of feathers for 160 individuals belonging to 85 species of birds in general linear mixed models to analyze allometry of feathers and to investigate possible factors explaining variation in the number of feathers. A phylogenetic effect was assessed by quantifying the random effect of genus.Results: The total mass of feathers increased isometrically with body mass, while the total number of feathers and the mean mass of feathers showed negative allometry. Negative allometry implied that small-sized species had relatively many small feathers. There was a negative association between the number of feathers and migration distance. The total number of feathers initially increased during fall and winter, consistent with individuals growing more feathers later during the year or with individuals with fewer feathers selectively disappearing from the population. In contrast, the number of feathers decreased from winter through spring and summer.Conclusions: These findings suggest that thermoregulation has affected the evolution of the number and the size of feathers, there is selection against feather loss, and that the number of feathers varies across seasons.展开更多
Recent discoveries of feathered dinosaurs from Early Cretaceous deposits in Liaoning,China,have not only lent strongest support for the dinosaurian hypothesis of bird origins,but have also provided much-needed informa...Recent discoveries of feathered dinosaurs from Early Cretaceous deposits in Liaoning,China,have not only lent strongest support for the dinosaurian hypothesis of bird origins,but have also provided much-needed information about the origins of feathers and avian flight.Preliminary analysis of character evolution suggests that the major avian osteological characters were acquired during the early evolution of maniraptoran dinosaurs.The available evidence also suggests that the first feathers with a filamentous morphology probably evolved in basal coelurosaurs and pennaceous feathers(including those with aerodynamic features)were developed in non-avian maniraptorans,indicating that feathers evolved before the origin of birds and their flight.An evolutionary model is proposed here to describe the major stages of feather evolution,a process characterized by a combination of both transformational and innovative modifications.This model is different from some recent developmental models,which suggest that feathers are evolutionary novelties without a homologous relationship to reptilian scales.Although non-avian theropods are traditionally regarded as distinctly cursorial animals,recent discoveries suggest that the closest relatives of birds might be arboreal theropods.Many bird features,such as the furcula and pennaceous feathers,evolved in a terrestrial context,whereas others,such as some pedal modifications,may have evolved in an arboreal context.Consequently,arboreality may have also contributed to the origin of avian flight.展开更多
We investigated the levels of nickel in the feathers of the Western Reef Heron (Egretta gularis) and Siberian Gull (Larus heuglini) from the Hara Biosphere Reserve in southern Iran from November to December 2010. Anal...We investigated the levels of nickel in the feathers of the Western Reef Heron (Egretta gularis) and Siberian Gull (Larus heuglini) from the Hara Biosphere Reserve in southern Iran from November to December 2010. Analysis of variance shows that no significant differences in nickel levels were found between gender and age groups in either species, but it should be pointed out that the number of samples was small. Student t tests show that the amount of nickel in the feathers of the Siberian Gull was higher than in the Western Reef Heron. The level of nickel concentration in the Western Reef Heron was higher in females than in males; on the other hand, this level of concentration in the Siberian Gull was higher in males.展开更多
基金supported by the National Natural Science Foundation of China(No.31970427 and 32270526 granted to W.L.).
文摘Nests are important structures for birds to raise their offspring and for signaling.Many birds incorporate feathers into the nest,since feathers were traditionally thought to serve the function of insulation.Hypotheses in recent years have considered that some birds place feathers in conspicuous locations in the nest for decoration to trigger a fear response in the competitors.In this study,we investigated whether decorative feathers could deter nest usurpation by Crested Mynas(Acridotheres cristatellus)by manipulating nest box contents.The results revealed that Crested Mynas preferred black feathers to white feathers as decorations and occupied nest boxes decorated with black feathers significantly less than those decorated with white feathers,suggesting that black decorative feathers in the nest could be more effective in preventing nest usurpation by Crested Mynas and that white decorative feathers may have other functions.The black feathers in the nest are prominently placed at the edge of the nest to convey the message that“this nest is occupied”or“the owner of this nest has been preyed upon”to visitor Crested Mynas,thus effectively preventing them from usurping the nest at a later stage.
文摘Background: Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss at other times of the year and its fitness consequences remain poorly known.Methods: I used information on the number and the mass of feathers for 160 individuals belonging to 85 species of birds in general linear mixed models to analyze allometry of feathers and to investigate possible factors explaining variation in the number of feathers. A phylogenetic effect was assessed by quantifying the random effect of genus.Results: The total mass of feathers increased isometrically with body mass, while the total number of feathers and the mean mass of feathers showed negative allometry. Negative allometry implied that small-sized species had relatively many small feathers. There was a negative association between the number of feathers and migration distance. The total number of feathers initially increased during fall and winter, consistent with individuals growing more feathers later during the year or with individuals with fewer feathers selectively disappearing from the population. In contrast, the number of feathers decreased from winter through spring and summer.Conclusions: These findings suggest that thermoregulation has affected the evolution of the number and the size of feathers, there is selection against feather loss, and that the number of feathers varies across seasons.
文摘Recent discoveries of feathered dinosaurs from Early Cretaceous deposits in Liaoning,China,have not only lent strongest support for the dinosaurian hypothesis of bird origins,but have also provided much-needed information about the origins of feathers and avian flight.Preliminary analysis of character evolution suggests that the major avian osteological characters were acquired during the early evolution of maniraptoran dinosaurs.The available evidence also suggests that the first feathers with a filamentous morphology probably evolved in basal coelurosaurs and pennaceous feathers(including those with aerodynamic features)were developed in non-avian maniraptorans,indicating that feathers evolved before the origin of birds and their flight.An evolutionary model is proposed here to describe the major stages of feather evolution,a process characterized by a combination of both transformational and innovative modifications.This model is different from some recent developmental models,which suggest that feathers are evolutionary novelties without a homologous relationship to reptilian scales.Although non-avian theropods are traditionally regarded as distinctly cursorial animals,recent discoveries suggest that the closest relatives of birds might be arboreal theropods.Many bird features,such as the furcula and pennaceous feathers,evolved in a terrestrial context,whereas others,such as some pedal modifications,may have evolved in an arboreal context.Consequently,arboreality may have also contributed to the origin of avian flight.
基金Dr. Pourkhabbaz, Mr. Nowrouzi and Mr. Salehi for their help throughout the project
文摘We investigated the levels of nickel in the feathers of the Western Reef Heron (Egretta gularis) and Siberian Gull (Larus heuglini) from the Hara Biosphere Reserve in southern Iran from November to December 2010. Analysis of variance shows that no significant differences in nickel levels were found between gender and age groups in either species, but it should be pointed out that the number of samples was small. Student t tests show that the amount of nickel in the feathers of the Siberian Gull was higher than in the Western Reef Heron. The level of nickel concentration in the Western Reef Heron was higher in females than in males; on the other hand, this level of concentration in the Siberian Gull was higher in males.
