title: Wood duck hatch date: relationship to pairing chronology, plasma luteinizing hormone, and steroid hormones during autumn and winter.
abstract: We examined variation in courtship activity and hormone levels of male and female wood ducks (Aix sponsa) in relation to hatch date. Young wood ducks were assigned in groups of 8 (4 males and 4 females) to 4 experimental pens; 2 pens contained early-hatched ducks (3-12 April) and 2 pens contained late-hatched ducks (7-16 June). Courtship behaviors occurred less frequently in October and November than in December and January-February for both early- and late-hatched groups. Early-hatched wood ducks participated in courtship more frequently and formed pair bonds sooner than late-hatched individuals. Testosterone (T) and androstenedione (AD) levels of males did not differ between treatment groups; however, average levels of luteinizing hormone (LH) were greater for early-hatched males. Differences in LH occurred in 2 of 12 samples (6 October and 3 November); otherwise, LH did not vary by treatment. Levels of T and LH in males varied temporally, but there was no significant temporal variation in AE levels. Temporal variation in hormone levels was similar for early- and late-hatched males. Estradiol (E), progesterone (P), and LH levels of females did not differ between treatment groups. There was temporal variation in levels of E and LH, but not of P; this variation was similar for early- and late-hatched females. These data indicate that behavioral differences occurring temporally and between early- and late-hatched wood ducks were not related to corresponding differences in hormone levels.
authors.affiliation: Department of Zoology and Wildlife Science, Auburn University, Alabama 36849-5414.
authors.forename: G R
authors.initials: GR
authors.lastname: Hepp
authors.forename: P
authors.initials: P
authors.lastname: Connolly
authors.forename: R A
authors.initials: RA
authors.lastname: Kennamer
authors.forename: W F
authors.initials: WF
authors.lastname: Harvey
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology*; D004967:Estrogens / Q000097:blood; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D010152:Pair Bond; D012621:Seasons; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013739:Testosterone / Q000097:blood
chemical_list: D004967:Estrogens; D012739:Gonadal Steroid Hormones; D013739:Testosterone; D007986:Luteinizing Hormone