hoskins-utilisationofintensive-2015.pdf (4.14 MB)
Utilisation of intensive foraging zones by female Australian fur seals
journal contributionposted on 2015-01-01, 00:00 authored by Andrew Hoskins, D P Costa, John ArnouldJohn Arnould
Within a heterogeneous environment, animals must efficiently locate and utilise foraging patches. One way animals can achieve this is by increasing residency times in areas where foraging success is highest (area-restricted search). For air-breathing diving predators, increased patch residency times can be achieved by altering both surface movements and diving patterns. The current study aimed to spatially identify the areas where female Australian fur seals allocated the most foraging effort, while simultaneously determining the behavioural changes that occur when they increase their foraging intensity. To achieve this, foraging behaviour was successfully recorded with a FastLoc GPS logger and dive behaviour recorder from 29 individual females provisioning pups. Females travelled an average of 118 ± 50 km from their colony during foraging trips that lasted 7.3 ± 3.4 days. Comparison of two methods for calculating foraging intensity (first-passage time and first-passage time modified to include diving behaviour) determined that, due to extended surface intervals where individuals did not travel, inclusion of diving behaviour into foraging analyses was important for this species. Foraging intensity 'hot spots' were found to exist in a mosaic of patches within the Bass Basin, primarily to the south-west of the colony. However, the composition of benthic habitat being targeted remains unclear. When increasing their foraging intensity, individuals tended to perform dives around 148 s or greater, with descent/ascent rates of approximately 1.9 m•s-1 or greater and reduced postdive durations. This suggests individuals were maximising their time within the benthic foraging zone. Furthermore, individuals increased tortuosity and decreased travel speeds while at the surface to maximise their time within a foraging location. These results suggest Australian fur seals will modify both surface movements and diving behaviour to maximise their time within a foraging patch.
SeasonArticle Number : e0117997
Pagination1 - 19
PublisherPublic Library of Science (PLOS)
LocationSan Francisco, Calif.
Publication classificationC Journal article; C1 Refereed article in a scholarly journal
Copyright notice2015, Public Library of Science (PLOS)
CategoriesNo categories selected
AnimalsAustraliaBehavior, AnimalDivingFeeding BehaviorFemaleFur SealsGeographyScience & TechnologyMultidisciplinary SciencesScience & Technology - Other TopicsAREA-RESTRICTED SEARCHSOUTHERN ELEPHANT SEALSLIONS PHOCARCTOS-HOOKERIAEROBIC DIVE LIMITOPTIMAL PATCH USE1ST PASSAGE TIMEMARINE PREDATORDIVING BEHAVIOR1ST-PASSAGE TIMEHABITAT USE