Thinking about Feathers: Adaptations of Golden Eagle Rectrices

  title={Thinking about Feathers: Adaptations of Golden Eagle Rectrices},
  author={David H. Ellis and James W. Lish},
ABSTRACT “Happy is the man whose lot it is to know The secrets of the earth.” Euripides Abstract The striking black and white plumage of the juvenile Golden Eagle (Aquila chrysaetos) provides an excellent opportunity to examine the possible selective forces influencing the strategic placement of dark pigment in birds. The conflict between opposing selective pressures (first, toward large white patches, which may allay aggression in adults, and second, toward dark plumage to promote camouflage… 
Predefinitive Plumage in the Golden Eagle (Aquila chrysaetos): A Signal of Aggression or Submission?
An additional selection pressure is proposed for the evolution of distinct immature plumage in Golden Eagles, which is termed the ‘‘aggression hypothesis’’ because inexperienced young Golden Eagles may have difficulties hunting live prey during harsh winter conditions in the northern hemisphere.
The importance of white on black: unmelanized plumage proportion predicts display complexity in birds
  • I. Galván
  • Biology
    Behavioral Ecology and Sociobiology
  • 2008
It is hypothesized that, given that the efficacy of visual displays basically depends on conspicuousness and level of performance, species with low levels of conspicuousness may be forced to perform more complex varieties of a given display to get the same signal efficiency than other more conspicuous species.
Sexually dimorphic melanin‐based colour polymorphism, feather melanin content, and wing feather structure in the barn owl (Tyto alba)
It is concluded that differently coloured individuals produce wing feathers of different strengths to adopt alternative behavioural and life history strategies, and wear resistance increases with darkness, whereas feathers of lighter coloured birds may bend less easily.
On the Uniqueness of Color Patterns in Raptor Feathers
Previous claims that complex color patterns in feather pairs are fingerprint-identical (and therefore that molted feathers from wild raptors can be used to identify breeding adults from year to year with certainty) were found to be untrue.
A bstrAct .- From fieldwork begun in 1979 and continuing intermittently until the present, we show the range in variation in pigmentation of Peregrine Falcons ( Falco peregrinus ) native to the
Condition-dependence of pheomelanin-based coloration in nuthatches Sitta europaea suggests a detoxifying function: implications for the evolution of juvenile plumage patterns
The detoxifying capacity of pheomelanin under low stress levels should be considered as an explanation for the evolution of both adult-like and distinctively juvenile plumage patterns.
A review of Gloger's rule, an ecogeographical rule of colour: definitions, interpretations and evidence
  • K. Delhey
  • Environmental Science
    Biological reviews of the Cambridge Philosophical Society
  • 2019
Since humidity seems to be the core climatic variable behind Gloger's rule, it is suggested that the two most plausible mechanisms are camouflage and protection against parasites/pathogens, the latter possibly through pleiotropic effects on the immune system.
First-Year Dispersal of Golden Eagles from Natal Areas in the Southwestern United States and Implications for Second-year Settling
Abstract Knowledge of dispersal from natal areas by pre-breeding-age Golden Eagles (Aquila chrysaetos) in North America is sparse, though crucial for conservation planning. During 2010–2015, we used


Color Convergence: Is it Only Mimetic?
This work is arguing that physical constraints can also produce convergence of color and pattern, and presents four examples that illustrate how physical constraints may operate.
Plumage Changes in the Golden Eagle
This paper is a preliminary report in which the process of molting as it occurs in this species and the individual and age variations which have made the study of this form so difficult are described.
The Mechanism of Feather Replacement during Natural Molt
The evidence to be presented in this paper indicates that this latter mechanism of feather replacement is more widespread among birds than previously believed and that natural molt is actively concerned only with the incoming generation.
Feather Pigmentation and Abrasion: Test of a Hypothesis
GOUDY, W. H., R. C. KLETZLY, & J. C. RIEFFENBERGER. 1970. Characteristics of a heavily hunted woodcock population in West Virginia. Trans. North Amer. Wildl. Nat. Res. Conf. 35: 183-195. MARTIN, F.
It is shown that feather-degrading bacteria degrade unmelanized white feathers more quickly and completely than melanized black feathers, and improves the understanding of these roles.
Melanin and the abrasion resistance of feathers
The pelagic smooth, C. lumpsucker, Aptocyclus ventricosus (Pallas), in the 1977, in the Aleutian Basin, p. 227-260.
Female plumage spottiness signals parasite resistance in the barn owl (Tyto alba)
This study is the first one showing that a heritable secondary sexual characteristics displayed by females reflects parasite resistance, and suggests that the ability to resist parasites covaries with the extent of female plumage spottiness.
Ptilochronology: Feather Growth Bars as Indicators of Nutritional Status
It is concluded that male Downy Woodpeckers normally have a better nutritional status than females during the winter, and Hypotheses that predict even minor variation in the nutritional status of birds should become accessible to testing.
The Handicap Principle: A Missing Piece of Darwin's Puzzle
The authors convincingly demonstrate that when an animal acts altruistically, it handicaps itself-assumes a risk or endures a sacrifice-not primarily to benefit its kin or social group but to increase its own prestige within the group and thus signal its status as a partner or rival.
Coat Color and Solar Heat Gain in Animals
A recent analysis of the relation between animal coat color and solar heat gain stated "there still is a question as to whether dark or light plumage is more effective in utilization of direct solar