The involvement of prolactin in avian molt: The effects of gender and breeding success on the timing of molt in Mute swans (Cygnus olor)

Abstract

The aim of the study was to test the hypothesis that decreasing plasma prolactin stimulates or permits the initiation of avian molt. Changes in the concentration of plasma prolactin in Mute swans (Cygnus olor) were compared in non-breeding singletons and breeding pairs. In breeding swans, the onset of molt is delayed compared to non-breeders, and is delayed further in breeding males compared to their female partners. The seasonal decrease in prolactin in non-breeding birds of both sexes started at the end of May and was associated with the initiation of molt 4 weeks later. The decrease in plasma prolactin in incubating females was more pronounced, as a consequence of increased prolactin secretion associated with incubation behaviour, but also started at end of May, and was associated the onset of moult 6 weeks later. In breeding males, plasma prolactin increased at the end of May when they started to care for their newly hatched cygnets. Correspondingly, prolactin began to decrease 3-5 weeks later in males than in females. These males started to molt in mid August, at least 4 weeks later than females. It is concluded that molt is related to decreasing plasma prolactin, and is inhibited when plasma prolactin is increasing or high.

Relationships among plumage coloration, blood selenium concentrations, and immune responses of adult and nestling tree swallows

“…One possibility is that brighter white females obtain nest sites located closer to prime foraging areas and are in better condition and able to mount a stronger immune response as a result. At a proximate level, it is possible that sex differences in the timing of molt (Hemborg, 1999;Dawson et al, 2009), seasonal hormone concentrations (Dawson et al, 2009;Small and Schoech, 2015) or immunity (Hasselquist, 2007) lead to different relationships between coloration and immunity in males and females.…”

Does prolactin mediate parental and life-history decisions in response to environmental conditions in birds? A review

“…Prolactin levels drop at the end of the parental phase when parental activities decrease or even stop and the post-breeding molt life-history stage starts a few days after (Crossin et al, 2012). For instance, Deviche et al (2000) showed that both the post-breeding decrease in prolactin levels and the onset of molt occur earlier in young Dark-eyed juncos relative to older juncos and Dawson et al (2009) found that both the decrease in prolactin levels and the onset of molt were delayed in males relative to females in mute swans. Dawson and Fig.…”

Calcineurin/Nfatc1 signaling links skin stem cell quiescence to hormonal signaling during pregnancy and lactation

“…Prl can control skin molting in newts (Dent et al 1973) and feather molting in avian species (Dawson and Sharp 1998;Dawson et al 2009;Crossin et al 2012). Seasonal Prl in combination with other hormones is thought to modulate annual changes in hair growth of several species, including sheep, deer, and voles (Duncan and Goldman 1984;Curlewis et al 1988;Smale et al 1990;Dicks et al 1996;Nixon et al 2002;Randall 2007).…”

“…In humans, patients with elevated serum Prl levels (or hyperprolactinemia) can experience hair loss (Orfanos and Hertel 1988;Foitzik et al 2009;Lutz 2012). Additionally, Prl has been implicated in the regulation of epidermal appendage growth in several avian and mammalian species (Duncan and Goldman 1984;Pearson et al 1996;Dawson and Sharp 1998;Nixon et al 2002;Dawson et al 2009). Prl receptors (Prlrs) are expressed within the HF in both mice and humans, and Prl can induce follicle death in cultured skin tissue from both species (Foitzik et al 2003(Foitzik et al , 2006.…”