Evol Ecol Res 13: 19-33 (2011)     Full PDF if your library subscribes.

Male-biased reproductive effort in a long-lived seabird

Robert A. Mauck1, Jennifer L. Zangmeister1, Jack C. Cerchiara1, Charles E. Huntington2 and Mark F. Haussmann1

1Biology Department, Kenyon College, Gambier, Ohio, USA and  2Biology Department, Bowdoin College, Brunswick, Maine, USA

Correspondence: R.A. Mauck, Biology Department, Kenyon College, Gambier, OH 43022, USA.
e-mail: mauckr@kenyon.edu


Background: In dimorphic seabirds, the larger sex tends to provision more than the smaller sex. In contrast, monogamy and biparental care are often associated with equal effort between the sexes. However, the few studies that have tested sex-specific effort in monomorphic seabirds have primarily examined the details of foraging at sea.

Hypotheses: Parental effort is also sex-biased in a monomorphic seabird mating system for one of two reasons: (1) If females enter the period of parental care less able to invest in care due to the cost of egg production, male-biased effort may be necessary to avoid reproductive failure. (2) Alternatively, female-biased effort may occur due to the initial disparity in gamete size, particularly in species with internal fertilization.

Organism: Leach’s storm-petrel (Oceanodroma leucorhoa), a monomorphic seabird with true monogamy and obligate biparental care.

Site: A breeding colony of Oceanodroma leucorhoa at the Bowdoin Scientific Station on Kent Island, Bay of Fundy, New Brunswick, Canada.

Methods: Across multiple breeding seasons, we assessed incubation behaviour and chick-rearing behaviour through one manipulative and multiple observational studies. We assessed energetic investment by inducing feather replacement and measuring the resulting rate of feather growth during both the incubation and chick-rearing phases of parental care.

Conclusions: We observed male-biased effort. Males incubated the egg for a greater proportion of time than did females and, when faced with an egg that would not hatch, males continued to incubate past the point when females abandoned it. Males made a higher percentage of total food deliveries to chicks than did females, resulting in greater mean daily food provisioning by males than by females. During chick rearing, males grew replacement feathers more slowly than did females, indicating that males were more likely to reduce their own nutritional condition while raising chicks than were females. These results support the hypothesis that females enter the period of parental care at a nutritional deficit and males must compensate to avoid reproductive failure.

Keywords: life-history trade-offs, parental effort, ptilochronology, sex-specific reproductive effort.

IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.


        © 2011 Robert A. Mauck. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

       Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.

       All copies of abstracts and articles must preserve their copyright notice without modification.