A sample of prebreeding season gonads of northern phalaropes showed a high ovarian ratio of testosterone/estradiol, and a greater concentration of testosterone in the ovaries than in the testes. These features correspond to those found in the gonads of Wilson's phalarope and differ from those found in the gonads of four other species of birds. In conjunction with the earlier demonstration that the nuptial plumage in this species is androgen-dependent, these facts explain the more colorful nuptial plumage of the female compared to that of the male northern phalarope.
An American White-Fronted Goose and Wilson's Phalarope in Essex County, Massachusetts
