• Publications
  • Influence
The "Challenge Hypothesis": Theoretical Implications for Patterns of Testosterone Secretion, Mating Systems, and Breeding Strategies
A combination of field and laboratory investigations has revealed that the temporal patterns of testosterone (T) levels in blood can vary markedly among populations and individuals, and even withinExpand
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Testosterone and Aggression in Birds
The familiar spring sound of birdsongs heralds the onset of territory formation and a complex sequence of interrelated events that make up the breeding period. Such songs are an integral part of theExpand
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Hormones, developmental plasticity and adaptation
Phenotypic plasticity is the extent to which an organism can change its physiology, behaviour, morphology and/or development in response to environmental cues. Environmentally induced differences inExpand
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The role of sex steroids in the acquisition and production of birdsong
Male birdsong is generally regarded as a secondary sexual characteristic under the control of gonadal steroids1,2. Song typically waxes and wanes with the seasonal cycle of testicular growth andExpand
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Vocal communication in the domestic chicken: II. Is a sender sensitive to the presence and nature of a receiver?
Abstract As a test of the automaticity of the food calling behaviour of cockerels, their sensitivity to the presence and nature of an audience was explored. Males were presented with either a highlyExpand
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Vocal communication in the domestic chicken: I. Does a sender communicate information about the quality of a food referent to a receiver?
Abstract Male domestic chickens produce ‘food calls’, when they are presented with food. Experiments, conducted under controlled conditions, on the responses of cockerels to the presentation ofExpand
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Sex determination of Red‐tailed Hawks (Buteo jamaicensis calurus) using DNA analysis and morphometrics
ABSTRACT Currently, the sex of Red-tailed hawks (Buteo jamaicensis) cannot be determined by in-hand methods. Males and females do not differ in plumage and overlap in size. We collected featherExpand
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Testosterone and survival: A cost of aggressiveness?
  • A. Dufty
  • Biology, Medicine
  • Hormones and Behavior
  • 1 June 1989
Free-living male brown-headed cowbirds were captured during the breeding season, implanted with testosterone-filled Silastic tubing, and released. Radioimmunoassay verified that the implantsExpand
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VARIATION IN THE STABLE-HYDROGEN ISOTOPE COMPOSITION OF NORTHERN GOSHAWK FEATHERS: RELEVANCE TO THE STUDY OF MIGRATORY ORIGINS
Abstract The analysis of stable-hydrogen isotope ratios in feathers (δDf) allows researchers to investigate avian movements and distributions to an extent never before possible. Nonetheless, naturalExpand
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