Seaweed provisioning behaviour confers thermal benefit for nesting Australasian gannets (Morus serrator).

Matthews, J. L., Ismar, Stefanie M. H. and Hauber, M. E. (2008) Seaweed provisioning behaviour confers thermal benefit for nesting Australasian gannets (Morus serrator). Behaviour, 145 . pp. 1823-1837. DOI 10.1163/156853908786279600.

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Abstract

Despite prolonged and obligate biparental care for a single offspring in the Australasian gannet Morus serrator, several reproductive behaviours are presumed to be sex specific and might indicate sexual dimorphism in mating and parental effort in this broadly monomorphic seabird. For instance, the delivery of seaweed as a nesting material has been typically considered a male specific trait. We assessed this assumption and determined whether the potential role of this behaviour is to serve as a nuptial trait preceeding copulation or to impart a thermal benefit for incubation. First, as predicted, all arriving individuals at the colony that mated following seaweed delivery assumed the top copulatory position, which is consistent with male behaviour in this species. In comparison, the likelihood of birds without seaweed copulating in top position upon arrival at the nest site was approx. 50%, indicating an even mix of the sexes. However, the sex of those individuals in our sample that did not copulate during our observations remains unresolved. Second, seaweed delivery was not related to copulation following arrival, as individuals arriving with seaweed in our sample had a lower probability of mating than did individuals arriving without seaweed. Third, to determine if seaweed provides thermoregulatory benefits to alleviate the physiological costs of incubation, the foot temperatures of incubating and non-incubating individuals and temperatures of nests with or without seaweed were recorded. Temperatures of the foot-webbings during incubation were significantly higher above ambient temperatures than those of non-incubating gannets at the colony. Nests that contained seaweed were significantly warmer at sunrise than those without seaweed. There was no consistent difference between the temperatures of nesting material in the evenings alone, with a large variance of evening nest temperatures. These correlative data are consistent with male specificity and thermoregulatory benefits associated with seaweed delivery in M. serrator, implying that further experimental work on known-sexed birds should focus on physiological benefits and reproductive consequences of seaweed delivery in this species

Document Type: Article
Keywords: incubation; sex-specificity; nest building; nuptial gift; thermal physiology; SULA-GRANTI; INCUBATION; INVESTMENT; EGGS; SUCCESS; MAGPIES; GROWTH
Refereed: Yes
Open Access Journal?: No
Publisher: Brill
Date Deposited: 04 Dec 2012 12:37
Last Modified: 19 Jun 2020 11:32
URI: https://oceanrep.geomar.de/id/eprint/19522

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