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Investigation of foraging decisions can help understand how animals efficiently gather and exploit food. Prey chase and handling times are important aspects of foraging efficiency, influencing the net energy gain derived from a prey item. However, these metrics are often overlooked in studies of foraging behaviour due to the difficulty in observing them. The present study used animal-borne cameras to investigate the type, duration and energetic consequences of predator-prey interactions in little penguins ( Eudyptula minor ) ( n = 32) from two colonies in Bass Strait, south-eastern Australia. A total of seven main prey items were observed and consumed by little penguins. Penguins were observed to consume prey types and use strategies that have not been previously documented. These included consumption of bellowsfish ( Macroramphosus scolopax ) and other fish species captured sheltering around jellyfish or extracted dead from the tentacles. Chase and handling time varied with prey type and lasted approximately 2 s for most prey. Profitability varied among prey types, with a greater amount of low profitable prey being consumed, suggesting a trade-off between minimizing energetic costs, and increasing capture rates. These results highlight the use of animal-borne video data loggers to further understand the foraging adaptations of important predators in the marine environment., Competing Interests: We declare we have no competing interests., (© 2023 The Authors.)

Quantifying prey characteristics is important for understanding the foraging behaviour of predators, which ultimately influence the structure and function of entire ecosystems. However, information available on prey is often at magnitudes which cannot be used to infer the fine-scale behaviour of predators, especially so in marine environments where direct observation of predator-prey interactions is rarely possible. In the present study, animal-borne video data loggers were used to determine the influence of prey type and patch density on the foraging behaviour of the little penguin ( Eudyptula minor ), an important predator in southeastern Australia. We found that numerical density positively influenced time spent foraging at a patch. However, when accounting for calorific value in density estimates, individuals spent longer at dense patches of low-quality prey. This may reflect a trade-off between capture effort and calorific gain as lower quality prey were captured at higher rates. During the breeding season, foraging trip distance and duration is constrained by the need to return to the colony each day to feed offspring. The results of the study suggest that, under these spatio-temporal constraints, little penguins maximize foraging performance by concentrating efforts at larger quantities of prey, irrespective of their calorific quality., (© 2022 The Authors.)

Effective conservation assessments require detailed information of species' ecological niches during the whole annual cycle. For seabirds, this implies investigating the at-sea distribution and foraging behaviour during both the breeding and non-breeding periods. However, until recently, collecting information about small species has been precluded by the excessive size of the required devices. This lack of knowledge is exacerbated in the case of polytypic genera with species sharing very similar appearance and behaviour, such as the super-abundant prions ( Pachyptila spp.). The present study investigates the year-round at-sea distribution and foraging ecology of the fairy prion ( Pachyptila turtur ) in southeastern Australia. Miniaturized GPS loggers during the breeding season and geolocators (GLS) during the non-breeding period were used over 4 consecutive years (2017-2021), with results that highlight the importance of the continental shelf-edge waters for fairy prions throughout the year. In addition, contrary to previous assumptions, the GLS data revealed an unsuspected post-breeding migration to the waters south of Australia, during which individuals probably undergo a rapid moult of flight feathers. Understanding the at-sea distribution and ecology of prions during the whole annual cycle will be fundamental to their conservation as it can reveal species- or population-specific threats that have been overlooked because of their status as abundant species., (© 2022 The Authors.)

Knowledge of factors affecting a species' breeding biology is crucial to understanding how environmental variability impacts population trajectories and enables predictions on how species may respond to global change. The Australian fur seal ( Arctocephalus pusillus doriferus , AUFS) represents the largest marine predator biomass in southeastern Australia, an oceanic region experiencing rapid warming that will impact the abundance and distribution of prey. The present study (1997-2020) investigated breeding phenology and pup production in AUFS on Kanowna Island, northern Bass Strait. The pupping period varied by 11 days and the median pupping date by 8 days and were negatively correlated to 1- and 2-year lagged winter zonal winds, respectively, within Bass Strait. While there was no temporal trend over the study period, annual pup production (1386-2574 pups) was negatively correlated to 1-year lagged summer zonal winds in the Bonney Upwelling region and positively correlated to the current-year Southern Oscillation Index (SOI). In addition, a fecundity index (ratio of new-born pups to adult females at the median pupping date) was positively correlated with current-year Southern Annular Mode (SAM) conditions. Periods of positive SOI and positive SAM conditions are forecast to increase in coming decades, suggesting advantageous conditions for the Kanowna Island AUFS population., Competing Interests: The authors declare no competing interests., (© 2022 The Authors.)

The highly dynamic nature of the marine environment can have a substantial influence on the foraging behaviour and spatial distribution of marine predators, particularly in pelagic marine systems. However, knowledge of the susceptibility of benthic marine predators to environmental variability is limited. This study investigated the influence of local-scale environmental conditions and large-scale climate indices on the spatial distribution and habitat use in the benthic foraging Australian fur seal ( Arctocephalus pusillus doriferus ; AUFS). Female AUFS provisioning pups were instrumented with GPS or ARGOS platform terminal transmitter tags during the austral winters of 2001-2019 at Kanowna Island, south-eastern Australia. Individuals were most susceptible to changes in the Southern Oscillation Index that measures the strength of the El Niño Southern Oscillation, with larger foraging ranges, greater distances travelled and more dispersed movement associated with 1-yr lagged La Niña-like conditions. Additionally, the total distance travelled was negatively correlated with the current year sea surface temperature and 1-yr lagged Indian Ocean Dipole, and positively correlated with 1-yr lagged chlorophyll- a concentration. These results suggest that environmental variation may influence the spatial distribution and availability of prey, even within benthic marine systems., (© 2021 The Authors.)

Most Procellariform seabirds are pelagic, breed in summer when prey availability peaks, and migrate for winter. They also display a dual foraging strategy (short and long trips) and sex-specific foraging. The Westland petrel Procellaria westlandica , a New Zealand endemic, is one of the rare seabirds breeding in winter. Preliminary findings on this large and sexually dimorphic petrel suggest a foraging behaviour with no evidence of a dual strategy, within a narrow range and with shared areas between sexes. To investigate further this unusual strategy, the present study determined the fine-scale at-sea behaviours (global positioning system and accelerometer data loggers) and trophic niches (stable isotopes in whole blood) of chick-rearing individuals (16 males and 13 females). All individuals foraged on the shelf-slope of the west coast of New Zealand's South Island with short, unimodal trips. Both sexes foraged at similar intensity without temporal, spatial or isotopic niche segregation. These findings suggest the presence of a winter prey resource close to the colony, sufficient to satisfy the nutritional needs of breeding without increasing the foraging effort or intra-specific competition avoidance during winter. Additional data are needed to assess the consistency of foraging niche between the sexes and its reproductive outcomes in view of anticipated environmental changes., Competing Interests: We have no competing interests., (© 2020 The Authors.)

The non-breeding period plays a major role in seabird survival and population dynamics. However, our understanding of the migratory behaviour, moulting and feeding strategies of non-breeding seabirds is still very limited, especially for small-sized species. The present study investigated the post-breeding behaviour of three distant populations (Kerguelen Archipelago, southeastern Australia, New Zealand) of the common diving petrel (CDP) ( Pelecanoides urinatrix ), an abundant, widely distributed zooplanktivorous seabird breeding throughout the southern Atlantic, Indian and Pacific oceans. The timing, geographical destination and activity pattern of birds were quantified through geolocator deployments during the post-breeding migration, while moult pattern of body feathers was investigated using stable isotope analysis. Despite the high energetic cost of flapping flight, all the individuals quickly travelled long distances (greater than approx. 2500 km) after the end of the breeding season, targeting oceanic frontal systems. The three populations, however, clearly diverged spatially (migration pathways and destinations), and temporally (timing and duration) in their post-breeding movements, as well as in their period of moult. Philopatry to distantly separated breeding grounds, different breeding phenologies and distinct post-breeding destinations suggest that the CDP populations have a high potential for isolation, and hence, speciation. These results contribute to improving knowledge of ecological divergence and evolution between populations, and inform the challenges of conserving migratory species., Competing Interests: We declare we have no competing interests., (© 2020 The Authors.)

Foraging is a behaviour that can be influenced by multiple factors and is highly plastic. Recent studies have shown consistency in individual foraging behaviour has serious ecological and evolutionary implications within species and populations. Such information is crucial to understand how species select habitats, and how such selection might allow them to adapt to the environmental changes they face. Five foraging metrics (maximum distance from the colony, bearing from the colony to the most distal point, tortuosity index, total number of dives and mean vectorial dynamic body acceleration were obtained using GPS tracking and accelerometry data in adult Australasian gannets ( Morus serrator ) from two colonies in southeastern Australia. Individuals were instrumented over two breeding seasons to obtain data to assess factors influencing foraging behaviour and behavioural consistency over multiple timescales (consecutive trips, breeding stages and years) and habitats (pelagic, mixed pelagic and inshore, and inshore). Colony, breeding stage and year were the factors which had the greatest influence on foraging behaviour, followed by sex. Behavioural consistency, measured as the contribution of the individual to the observed variance, was low to moderate for all foraging metrics (0.0-27.05%), with the higher values occurring over shorter timescales. In addition, behavioural consistency was driven by spatio-temporal factors rather than intrinsic characteristics. Behavioural consistency was higher in individuals foraging in inshore than pelagic habitats or mixed pelagic/inshore strategy, supporting suggestions that consistency is favoured in stable environments., Competing Interests: The authors of this manuscript declare no competing interests., (© 2020 The Authors.)

While marine top predators can play a critical role in ecosystem structure and dynamics through their effects on prey populations, how the predators function in this role is often not well understood. In the Benguela region of southern Africa, the Cape fur seal ( Arctocephalus pusillus pusillus ) population constitutes the largest marine top predator biomass, but little is known of its foraging ecology other than its diet and some preliminary dive records. Dive information was obtained from 32 adult females instrumented with dive recorders at the Kleinsee colony (29°34.17' S, 16°59.80' E) in South Africa during 2006-2008. Most dives were in the depth range of epipelagic prey species (less than 50 m deep) and at night, reflecting the reliance of Cape fur seals on small, vertically migrating, schooling prey. However, most females also performed benthic dives, and benthic diving was prevalent in some individuals. Benthic diving was significantly associated with the frequency with which females exceeded their aerobic dive limit. The greater putative costs of benthic diving highlight the potential detrimental effects to Cape fur seals of well-documented changes in the availability of epipelagic prey species in the Benguela., Competing Interests: The author and co-authors of this manuscript have no competing interests., (© 2019 The Authors.)