Hormonal changes associated with natural and manipulated incubation in the sex-role reversed Wilson's phalarope

Lewis W. Oring, Albert J. Fivizzani, Mark A. Colwell, Mohamed E. El Halawani

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45 Scopus citations


Wilson's phalarope (Phalaropus tricolor) is characterized by intense female intrasexual competition and exclusive male parental care. Females occasionally are polyandrous and no territories are defended. Prolactin (Prl) and testosterone (T) were analyzed from plasma samples obtained from individuals of different reproductive stages. Males tended to have higher plasma Prl levels than females throughout the breeding season. Prolactin levels of males declined posthatch, reaching baseline levels when chicks were approximately 9 days old-the time when chicks approach thermal independence and brooding is minimal. Testosterone levels dropped at the onset of incubation and remained low through the brooding period. Eggs were manipulated such that some males incubated clutches for shortened periods, others for extended periods. Regardless of the length of incubation, Prl levels were determined primarily by environmental events, i.e., incubation, hatching, and brooding.

Original languageEnglish (US)
Pages (from-to)247-256
Number of pages10
JournalGeneral and Comparative Endocrinology
Issue number2
StatePublished - Nov 1988

Bibliographical note

Funding Information:
The field assistance of Beverly Collier, Tammie Col-well, David Delehanty, Suzanne Fellows, Roberta Harvey, and Kim Sepanski; assistance with paper preparation of Linda Miller and Suzanne Fellows; and the laboratory assistance of Janet Silsby, Suzie Moser, and Linda Miller were invaluable. Clint Jorgenson and Phil Taylor provided logistical help. This research was supported by United States National Science Foundation Grants PCM 8315758 and DCB 8608162, and by the National Geographic Society and Canadian Wildlife Service. The comments of two anonymous reviewers benefitted this paper considerably.


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