Testosterone increases display behaviors but does not stimulate growth of adult plumage in male golden-collared manakins ( Manacus vitellinus)

• Published in: Hormones and behavior Vol. 49; no. 2; pp. 223 - 232
• Main Authors: Day, Lainy B., McBroom, Jennifer T., Schlinger, Barney A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01-02-2006; Elsevier; Elsevier BV
• Subjects: Animal ethology; Animals; Aves; Behavioral psychophysiology; Biological and medical sciences; Birds; Birds - physiology; Courtship display; Drug Implants; Feathers - drug effects; Feathers - growth & development; Female; Fundamental and applied biological sciences. Psychology; Hormones and behavior; Lek; Male; Manacus; Manacus vitellinus; Manakins; Plumage; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Regeneration - drug effects; Sex Characteristics; Sexual Behavior, Animal - drug effects; Stimulation, Chemical; Testosterone; Testosterone - pharmacology; Vertebrata; Vocalization, Animal - drug effects; Testosterone; Lek; Courtship display; Birds; Plumage; Manacus; Manakins; Human; Androgen; Growth; Sexual behavior; Male; Courtship behavior; Breeding behavior; Vertebrata; Adult; Testicular hormone; Sex steroid hormone; Aves
• ISSN: 0018-506X; 1095-6867
• DOI: 10.1016/j.yhbeh.2005.07.006

In order to attract females, male golden-collared manakins gather in leks and perform a complex display consisting of acrobatics accompanied by loud “wingsnapping”. During this display, males show off their yellow beard and yellow, black, and green plumage that is striking in comparison to the dull green plumage of young males and females. We investigated the role of testosterone (T) in activating the display of manakins and in stimulating the growth of the adult male plumage. T regulates song, copulation, and territorial aggression in temperate species. In tropical species, however, T levels can be relatively low year round, which has raised questions about the involvement of T in courtship display and male aggression in these species. In neither temperate nor tropical species has the role of hormones in the shift from juvenile to adult plumage been well studied. Therefore, we implanted green-plumaged birds and adult males with either a T pellet or an inert pellet (controls) and observed the display behaviors of these birds in the field and in captivity. In captive birds, we also plucked feathers from sexually dimorphic regions and observed color and regeneration rate of new feathers. We found that birds implanted with T increased several display behaviors compared to controls. All plucked feathers grew back the same color as prior to treatment; however, we observed some differences in feather growth rate between T-treated birds and controls.