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Flexibility in the parental effort of an Arctic-breeding seabird

TitleFlexibility in the parental effort of an Arctic-breeding seabird
Publication TypeJournal Article
Year of Publication2009
AuthorsHarding, AMA, Kitaysky, AS, Hall, ME, Welcker, J, Karnovsky, NJ, Talbot, SL, Hamer, KC, Gremillet, D
JournalFunctional Ecology

1.Parental investment strategies are considered to represent a trade-off between the benefits ofinvestment in current offspring and costs to future reproduction. Due to their high residual reproductivevalue, long-lived organisms are predicted to be more reluctant to increase parental effort.2.We tested the hypothesis that breeding little auks (Alle alle) have a fixed level of reproductiveinvestment, and thus reduce parental effort when costs associated with reproduction increase.3.To test this hypothesis we experimentally increased the flight costs of breeding little auks viafeather clipping. In 2005 we examined changes in the condition of manipulated parents, of themates of manipulated parents, and of their chick as direct measures of change in parental resourceallocation between self-maintenance and current reproduction. In 2007 we increased sample sizesto determine whether there was a physiological cost (elevated corticosterone, CORT) associatedwith the manipulation.4.We found that: (i) clipped birds and their mates lost more body mass than controls, but there wasno difference in mass loss between members of a pair; (ii) clipped birds had higher CORT levels thancontrol birds; (iii) there were no inter-annual differences in body mass and CORT levels betweenclipped individuals and their mates at recapture, and (iv) chicks with a clipped parent had lowerpeak and fledging mass, and higher CORT levels than control chicks in both years.5.Contrary to our hypothesis, the reduction in body mass of partners to clipped birds suggests thatlittle auks can increase parental effort to some extent. Nonetheless, the lower fledging mass andhigher CORT of chicks with a clipped parent indicates provisioning rates may not have been fullymaintained.6.As predicted by life-history theory, there may be a threshold to the additional reproductive costsbreeders will accept, with parents prioritizing self-maintenance over increased provisioning effortwhen foraging costs become too high.

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