title: Environmental influences on Adelie penguin breeding schedules, endocrinology, and chick survival.
abstract: To understand how the social and physical environment influences behaviour, reproduction and survival, studies of underlying hormonal processes are crucial; in particular, interactions between stress and reproductive responses may have critical influences on breeding schedules. Several authors have examined the timing of breeding in relation to environmental stimuli, while others have independently described endocrine profiles. However, few studies have simultaneously measured endocrine profiles, breeding behaviour, and offspring survival across seasons. We measured sex and stress hormone concentrations (oestrogens, testosterone, and corticosterone), timing of breeding, and chick survival, in Adelie penguins (Pygoscelis adeliae) at two colonies in two different years. Clutch initiation at Cape Bird South (CBS; year 1, ~14,000 pairs) occurred later than at Cape Crozier East (CCE; year 2, ~ 25,000 pairs); however, breeding was more synchronous at CBS. This pattern was probably generated by the persistence of extensive sea ice at CBS (year 1). Higher corticosterone metabolite and lower sex hormone concentrations at CBS correlated with later breeding and lower chick survival compared to at CCE - again, a likely consequence of sea ice conditions. Within colonies, sub-colony size (S, 50-100; M, 200-300; L, 500-600; XL, >1000 pairs) did not influence the onset or synchrony of breeding, chick survival, or hormone concentrations. We showed that the endocrine profiles of breeding Adelie penguins can differ markedly between years and/or colonies, and that combining measures of endocrinology, behaviour, and offspring survival can reveal the mechanisms and consequences that different environmental conditions can have on breeding ecology.
authors.affiliation: Department of Biological Sciences, University of Waikato, Hamilton 3240, New Zealand. calum.ninnes@gmail.com
authors.forename: C E
authors.initials: CE
authors.lastname: Ninnes
authors.forename: J R
authors.initials: JR
authors.lastname: Waas
authors.forename: N
authors.initials: N
authors.lastname: Ling
authors.forename: S
authors.initials: S
authors.lastname: Nakagawa
authors.forename: J C
authors.initials: JC
authors.lastname: Banks
authors.forename: D G
authors.initials: DG
authors.lastname: Bell
authors.forename: A
authors.initials: A
authors.lastname: Bright
authors.forename: P W
authors.initials: PW
authors.lastname: Carey
authors.forename: J
authors.initials: J
authors.lastname: Chandler
authors.forename: Q J
authors.initials: QJ
authors.lastname: Hudson
authors.forename: J R
authors.initials: JR
authors.lastname: Ingram
authors.forename: K
authors.initials: K
authors.lastname: Lyall
authors.forename: D K J
authors.initials: DK
authors.lastname: Morgan
authors.forename: M I
authors.initials: MI
authors.lastname: Stevens
authors.forename: J
authors.initials: J
authors.lastname: Wallace
authors.forename: E
authors.initials: E
authors.lastname: Möstl
mesh_terms: D000818:Animals; D001947:Breeding; D003345:Corticosterone / Q000378:metabolism; D004704:Endocrinology; D004967:Estrogens / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D005260:Female; D007124:Immunoenzyme Techniques; D008297:Male; D012098:Reproduction / Q000502:physiology*; D046429:Spheniscidae / Q000378:metabolism / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism
chemical_list: D004967:Estrogens; D013739:Testosterone; D003345:Corticosterone