Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support

Testosterone and Daylength-Dependent Development of Comb Size and Breeding Plumage of Male Willow Ptarmigan (Lagopus lagopus lagopus)

Karl-Arne Stokkan
The Auk
Vol. 96, No. 1 (Jan., 1979), pp. 106-115
Stable URL: http://www.jstor.org/stable/4085405
Page Count: 10
  • Read Online (Free)
  • Download ($15.00)
  • Subscribe ($19.50)
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
Testosterone and Daylength-Dependent Development of Comb Size and Breeding Plumage of Male Willow Ptarmigan (Lagopus lagopus lagopus)
Preview not available

Abstract

Photostimulation of male Willow Ptarmigan resulted in a rapid molt from the white winter plumage to the pigmented plumage of the breeding bird. In castrated ptarmigan the breeding plumage was omitted, resulting in a slow molt from white to pigmented summer (post-nuptial) plumage. Feathers were plucked from the head and back of castrated and intact birds kept on short daylength to investigate the effects of testosterone on feather pigmentation. Both castration and testosterone treatment resulted in pigmentation of regenerating feathers, while the untreated, intact birds regenerated white feathers. Pigmented feathers that regenerated on short daylengths in castrated or testosterone-treated birds were similar to each other, but were not the same as any type of pigmented feather seen in intact or castrated birds exposed to long daylengths. Pigmented feathers that generated in testosterone-treated intact or castrated birds on long daylengths were the same as feathers in breeding males. When compared with control birds, testosterone treatment shortened the interval between photostimulation and the beginning of the molt, while castration markedly lengthened this interval. Together with the photostimulated development of pigmented breeding plumage in intact males, there was a 100% increase of comb height. Castrates did not show any comb growth, whereas testosterone treatment always resulted in a rapid comb growth, both in intact males on short daylengths and in castrates on short daylengths and on long daylengths. In the male Willow Ptarmigan, testosterone and perhaps gonadotrophins (LH) affect the pigment producing system. There is a daylength dependent testosterone induction of molt from winter to breeding plumage, and a testosterone-stimulated and a testosterone-dependent comb growth.

Page Thumbnails

  • Thumbnail: Page 
106
    106
  • Thumbnail: Page 
107
    107
  • Thumbnail: Page 
108
    108
  • Thumbnail: Page 
109
    109
  • Thumbnail: Page 
110
    110
  • Thumbnail: Page 
111
    111
  • Thumbnail: Page 
112
    112
  • Thumbnail: Page 
113
    113
  • Thumbnail: Page 
114
    114
  • Thumbnail: Page 
115
    115