title: Drivers of time-activity budget variability during breeding in a pelagic seabird.
abstract: During breeding, animal behaviour is particularly sensitive to environmental and food resource availability. Additionally, factors such as sex, body condition, and offspring developmental stage can influence behaviour. Amongst seabirds, behaviour is generally predictably affected by local foraging conditions and has therefore been suggested as a potentially useful proxy to indicate prey state. However, besides prey availability and distribution, a range of other variables also influence seabird behavior, and these need to be accounted for to increase the signal-to-noise ratio when assessing specific characteristics of the environment based on behavioural attributes. The aim of this study was to use continuous, fine-scale time-activity budget data from a pelagic seabird (Cape gannet, Morus capensis) to determine the influence of intrinsic (sex and body condition) and extrinsic (offspring and time) variables on parent behaviour during breeding. Foraging trip duration and chick provisioning rates were clearly sex-specific and associated with chick developmental stage. Females made fewer, longer foraging trips and spent less time at the nest during chick provisioning. These sex-specific differences became increasingly apparent with chick development. Additionally, parents in better body condition spent longer periods at their nests and those which returned later in the day had longer overall nest attendance bouts. Using recent technological advances, this study provides new insights into the foraging behaviour of breeding seabirds, particularly during the post-guarding phase. The biparental strategy of chick provisioning revealed in this study appears to be an example where the costs of egg development to the female are balanced by paternal-dominated chick provisioning particularly as the chick nears fledging.
authors.affiliation: DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology, Nelson Mandela Metropolitan University, Summerstrand, South Africa.
authors.forename: Gavin M
authors.initials: GM
authors.lastname: Rishworth
authors.affiliation: Institut de Recherche pour le Développement (IRD), UMR EME-212 Exploited Marine Ecosystems, Centre de Recherche Halieutique Méditerranéenne et Tropicale, Sète cedex, France; Instituto del mar del Peru (IMARPE), Esquina Gamarra y gal Valle s/n Chucuito Callao, Peru.
authors.forename: Yann
authors.initials: Y
authors.lastname: Tremblay
authors.affiliation: DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology, Nelson Mandela Metropolitan University, Summerstrand, South Africa.
authors.forename: David B
authors.initials: DB
authors.lastname: Green
authors.affiliation: DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology, Nelson Mandela Metropolitan University, Summerstrand, South Africa.
authors.forename: Maëlle
authors.initials: M
authors.lastname: Connan
authors.affiliation: DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology, Nelson Mandela Metropolitan University, Summerstrand, South Africa.
authors.forename: Pierre A
authors.initials: PA
authors.lastname: Pistorius
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology*; D049628:Body Size; D001947:Breeding; D005247:Feeding Behavior; D005260:Female; D008297:Male; D009425:Nesting Behavior; D012737:Sex Factors; D012726:Sexual Behavior, Animal; D013019:South Africa; D013997:Time Factors