title: Mothers under stress? Hatching sex ratio in relation to maternal baseline corticosterone in the common tern (Sterna hirundo).
abstract: Sex ratio of progeny should be balanced if costs and benefits of rearing sons and daughters are equal. However, shifts in sex ratio have been demonstrated across bird species and it was suggested that females are able to adjust the primary sex ratio. One possible mechanism is the glucocorticoid corticosterone which rises under stressful conditions and can be deposited into egg yolk by mothers. We analysed primary sex ratio of common terns Sterna hirundo from 2006 to 2008 and related it to maternal baseline corticosterone level, laying date and year. Therefore, we took 101 blood samples of 71 breeding females via blood sucking bugs, a method with negligible stress for the birds. Sex ratio did not differ from parity in any of the analysed years, which were characterized by poor food availability and breeding success. Only within 1 year there was a tendency for more females in the last hatched chick. Neither corticosterone level nor laying date or year showed an influence on hatching sex ratio. The negative result concerning primary sex ratio and maternal baseline corticosterone level might suggest conditions to be good enough for mothers to prevent them from depositing high levels of corticosterone into eggs.
authors.affiliation: Institute of Avian Research, "Vogelwarte Helgoland", An der Vogelwarte 21, 26386 Wilhelmshaven, Germany. juliane.riechert@ifv-vogelwarte.de
authors.forename: Juliane
authors.initials: J
authors.lastname: Riechert
authors.forename: Olivier
authors.initials: O
authors.lastname: Chastel
authors.forename: Peter H
authors.initials: PH
authors.lastname: Becker
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D015415:Biomarkers / Q000097:blood; D001947:Breeding; D046091:Charadriiformes / Q000097:blood*; D003345:Corticosterone / Q000097:blood*; D004530:Egg Yolk / Q000378:metabolism*; D005260:Female; D008297:Male; D008425:Maternal Behavior; D009752:Nutritional Status; D010298:Parity; D019849:Sex Determination Processes; D012744:Sex Ratio; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D015415:Biomarkers; D003345:Corticosterone
references.citation: Physiol Zool. 1997 Jan-Feb;70(1):68-73
references.pmid: 9231378
references.citation: Proc Biol Sci. 2006 May 7;273(1590):1093-8
references.pmid: 16600886
references.citation: J Evol Biol. 2007 Jul;20(4):1522-30
references.pmid: 17584245
references.citation: Comp Biochem Physiol A Mol Integr Physiol. 2005 Jan;140(1):73-9
references.pmid: 15664315
references.citation: Gen Comp Endocrinol. 2012 Sep 1;178(2):391-9
references.pmid: 22750538
references.citation: Gen Comp Endocrinol. 2004 Feb;135(3):365-71
references.pmid: 14723888
references.citation: Mol Ecol. 2000 Aug;9(8):1123-9
references.pmid: 10964231
references.citation: Science. 1973 Jan 5;179(4068):90-2
references.pmid: 4682135
references.citation: Gen Comp Endocrinol. 2009 Sep 1;163(1-2):208-13
references.pmid: 19135999
references.citation: Nature. 2001 Aug 2;412(6846):498-9
references.pmid: 11484039
references.citation: Horm Behav. 2008 Jan;53(1):140-8
references.pmid: 17991465
references.citation: Biol Rev Camb Philos Soc. 2003 Nov;78(4):553-74
references.pmid: 14700391
references.citation: Proc Biol Sci. 1999 Aug 22;266(1429):1655-61
references.pmid: 10501037
references.citation: J Anim Ecol. 2006 Nov;75(6):1379-86
references.pmid: 17032370
references.citation: Proc Natl Acad Sci U S A. 1999 Jan 19;96(2):570-3
references.pmid: 9892674
references.citation: J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2011 Oct;197(10):1009-20
references.pmid: 21735224
references.citation: J Anim Ecol. 2007 Nov;76(6):1181-91
references.pmid: 17922714
references.citation: Proc Biol Sci. 2006 Sep 7;273(1598):2227-31
references.pmid: 16901843
references.citation: Physiol Biochem Zool. 2007 May-Jun;80(3):283-92
references.pmid: 17390284
references.citation: Am Nat. 2005 Dec;166(6):751-66
references.pmid: 16475090
references.citation: Gen Comp Endocrinol. 2000 Apr;118(1):113-22
references.pmid: 10753573
references.citation: Ecology. 2007 Oct;88(10):2496-504
references.pmid: 18027753
references.citation: Trends Ecol Evol. 2009 Nov;24(11):634-42
references.pmid: 19679371