Impacts of experimentally increased foraging effort on the family: offspring sex matters

• Published in: Animal behaviour Vol. 78; no. 2; pp. 321 - 328
• Main Authors: Harding, A.M.A., Kitaysky, A.S., Hamer, K.C., Hall, M.E., Welcker, J., Talbot, S.L., Karnovsky, N.J., Gabrielsen, G.W., Grémillet, D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01-08-2009; Elsevier; Harcourt Brace Jovanovich Ltd
• Subjects: Alle alle; Animal ethology; Animal reproduction; Aves; Biological and medical sciences; Birds; compensatory care; dovekie; Fundamental and applied biological sciences. Psychology; little auk; parental investment; Predation; provisioning decision; Psychology. Psychoanalysis. Psychiatry; sex allocation theory; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; provisioning decision; Alle alle; dovekie; compensatory care; sex allocation theory; little auk; parental investment; Social environment; Sex allocation; Feeding behavior; Theory; Sex; Foraging behavior; Breeding behavior; Decision; Marine environment; Aquatic environment; Progeny; Reproduction; Vertebrata; Family environment; Parental investment; Aves
• ISSN: 0003-3472; 1095-8282
• DOI: 10.1016/j.anbehav.2009.05.009

We examined how short-term impacts of experimentally increased foraging effort by one parent reverberate around the family in a monomorphic seabird (little auk,
Alle alle), and whether these effects depend on offspring sex. In many species, more effort is required to rear sons successfully than daughters. However, undernourishment may have stronger adverse consequences for male offspring, which could result in a lower fitness benefit of additional parental effort when rearing a son. We tested two alternative hypotheses concerning the responses of partners to handicapping parents via feather clipping: partners rearing a son are (1) more willing or able to compensate for the reduced contribution of their mate, or (2) less willing or able to compensate, compared to those rearing a daughter. Hypothesis 1 predicts that sons will be no more adversely affected than daughters, and the impact on parents will be greater when rearing a son. Hypothesis 2 predicts that sons will be more adversely affected than daughters, and parents raising a son less affected. Although experimental chicks of both sexes fledged in poorer condition than controls, sons attained higher mass and more rapid growth than daughters in both groups. Clipped parents lost a similar proportion of their initial mass regardless of chick sex, whereas partners of clipped birds lost more mass when rearing a son. These results support hypothesis 1: impacts of increased foraging effort by one parent were felt by offspring, regardless of their sex, and by the partners of manipulated birds, particularly when the offspring was male.