Habitat-specific foraging strategies in australasian gannets

• Main Authors: MR Wells, LP Angel, John Arnould
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2016
• Subjects: Other biological sciences not elsewhere classified; Science & Technology; Life Sciences & Biomedicine; Biology; Life Sciences & Biomedicine - Other Topics; Bio-logging; Camera; GPS; Foraging ecology; Local enhancement; Seabirds; PORT-PHILLIP BAY; LONG-TERM TRENDS; MORUS-SERRATOR; SOUTHERN-OCEAN; CAPE GANNETS; INDIVIDUAL SPECIALIZATION; PHENOTYPIC PLASTICITY; COMMERCIAL FISHERIES; CLIMATE-CHANGE; NEW-ZEALAND; 060201 Behavioural Ecology; 060205 Marine and Estuarine Ecology (incl Marine Ichthyology); 970106 Expanding Knowledge in the Biological Sciences; School of Life and Environmental Sciences; 3103 Ecology; 3109 Zoology; Southern Ocean; New Zealand
• Online Access: http://hdl.handle.net/10536/DRO/DU:30084282; https://figshare.com/articles/journal_contribution/Habitat-specific_foraging_strategies_in_australasian_gannets/20879998

ABSTRACT Knowledge of top predator foraging adaptability is imperative for predicting their biological response to environmental variability. While seabirds have developed highly specialised techniques to locate prey, little is known about intraspecific variation in foraging strategies with many studies deriving information from uniform oceanic environments. Australasian gannets (Morus serrator) typically forage in continental shelf regions on small schooling prey. The present study used GPS and video data loggers to compare habitat-specific foraging strategies at two sites of contrasting oceanographic regimes (deep water near the continental shelf edge, n=23; shallow inshore embayment, n=26), in south-eastern Australia. Individuals from the continental shelf site exhibited pelagic foraging behaviours typical of gannet species, using local enhancement to locate and feed on small schooling fish; in contrast only 50% of the individuals from the inshore site foraged offshore, displaying the typical pelagic foraging strategy. The remainder adopted a strategy of searching sand banks in shallow inshore waters in the absence of conspecifics and other predators for large, single prey items. Furthermore, of the individuals foraging inshore, 93% were male, indicating that the inshore strategy may be sex-specific. Large inter-colony differences in Australasian gannets suggest strong plasticity in foraging behaviours, essential for adapting to environmental change.