title: Melatonin delays clutch initiation in a wild songbird.
abstract: The hormone melatonin is known to play an important role in regulating many seasonal changes in physiology, morphology and behaviour. In birds, unlike in mammals, melatonin has thus far been thought to play little role in timing seasonal reproductive processes. This view is mainly derived from laboratory experiments on male birds. This study tests whether melatonin is capable of influencing the timing of clutch initiation in wild female songbirds. Free-living female great tits (Parus major) treated with melatonin-filled implants prior to the breeding season initiated their first clutch of the season significantly later than females carrying an empty implant. Melatonin treatment did not affect clutch size. Further, melatonin treatment did not delay the onset of daily activity in the wild nor adversely affect body mass in captivity compared with controls. These data suggest a previously unknown role for this hormone in regulating the timing of clutch initiation in the wild.
authors.affiliation: Department of Migration and Immuno-ecology, Max Planck Institute for Ornithology, Radolfzell, Germany. tgreives@orn.mpg.de
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Greives
authors.forename: Sjouke A
authors.initials: SA
authors.lastname: Kingma
authors.forename: Giulia
authors.initials: G
authors.lastname: Beltrami
authors.forename: Michaela
authors.initials: M
authors.lastname: Hau
mesh_terms: D000818:Animals; D001835:Body Weight; D052284:Clutch Size; D005260:Female; D005858:Germany; D008550:Melatonin / Q000378:metabolism*; D009043:Motor Activity; D012098:Reproduction; D012621:Seasons; D020308:Songbirds / Q000502:physiology*; D013997:Time Factors
chemical_list: D008550:Melatonin