Behaviourally mediated predation avoidance in penguin prey:<i>in situ</i>evidence from animal-borne camera loggers

Handley, Jonathan; Thiebault, Andréa; Stanworth, Andrew; Schutt, David; Pistorius, Pierre A.

doi:10.1098/rsos.171449

Cited by 26 publications

(24 citation statements)

References 41 publications

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“…2006, Handley & Pistorius, 2016, Handley et al . 2018), fisheries (Votier et al . 2013), conspecifics (Takahashi et al .…”

Section: Collection Of Digital Imagerymentioning

confidence: 99%

“…2014, Handley et al . 2018). Battery power is a greater limitation than data storage capacity for cameras connected to a transmitter because the data can be relayed to a remote downloading station (Moll et al .…”

Section: Collection Of Digital Imagerymentioning

confidence: 99%

“…Cameras on seabirds have been particularly useful for providing insight into foraging behaviours. This includes foraging habitat selection (Watanuki et al 2008), movement patterns (Ponganis et al 2000, and interactions with prey (Gr emillet et al 2006, Handley & Pistorius, 2016, Handley et al 2018, fisheries (Votier et al 2013), conspecifics (Takahashi et al 2004, Yoda et al 2011 and other predator species during foraging (Sakamoto et al 2009, Yoda et al 2011.…”

Section: Animal-borne Camerasmentioning

confidence: 99%

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Applications of digital imaging and analysis in seabird monitoring and research

Edney

Wood

2020

Ibis

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Rapid advances in digital imaging technology offer efficient and cost‐effective methods for measuring seabird abundance, breeding success, phenology, survival and diet. These methods can facilitate understanding of long‐term population trends, and the design and implementation of successful conservation strategies. This paper reviews the suitability of satellites, manned aircraft, unmanned aerial vehicles (UAVs), and fixed‐position, handheld and animal‐borne cameras for recording digital photographs and videos used to measure seabird demographic and behavioural parameters. It considers the disturbance impacts, accuracy of results obtained, cost‐effectiveness and scale of monitoring possible compared with ‘traditional’ fieldworker methods. Given the ease of collecting large amounts of imagery, image processing is an important step in realizing the potential of this technology. The effectiveness of manual, semi‐automated and automated image processing is also reviewed. Satellites, manned aircraft and UAVs have most commonly been used for population counts. Spatial resolution is lowest in satellites, limiting monitoring to large species and those with obvious signs of presence, such as penguins. Conversely, UAVs have the highest spatial resolution, which has allowed fine‐scale measurements of foraging behaviour. Time‐lapse cameras are more cost‐effective for collecting time‐series data such as breeding success and phenology, as human visits are only required infrequently for maintenance. However, the colony of interest must be observable from a single vantage point. Handheld, animal‐borne and motion‐triggered cameras have fewer cost‐effective uses but have provided information on seabird diet, foraging behaviour and nest predation. The last of these has been important for understanding the impact of invasive mammals on seabird breeding success. Advances in automated image analysis are increasing the suitability of digital photography and videography to facilitate and/or replace traditional seabird monitoring methods. Machine‐learning algorithms, such as Pengbot, have allowed rapid identification of birds, although training requires thousands of pre‐annotated photographs. Digital imaging has considerable potential in seabird monitoring, provided that appropriate choices are available for both image capture technology and image processing. These technologies offer opportunities to collect data in remote locations and increase the number of sites monitored. The potential to include such solutions in seabird monitoring and research will develop as the technology evolves, which will be of benefit given funding challenges in monitoring and conservation.

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“…2006, Handley & Pistorius, 2016, Handley et al . 2018), fisheries (Votier et al . 2013), conspecifics (Takahashi et al .…”

Section: Collection Of Digital Imagerymentioning

confidence: 99%

Section: Collection Of Digital Imagerymentioning

confidence: 99%

Section: Animal-borne Camerasmentioning

confidence: 99%

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Applications of digital imaging and analysis in seabird monitoring and research

Edney

Wood

2020

Ibis

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“…Since only a small proportion of the observed capture attempts were preceded with a vocalisation, they cannot be a prerequisite for efficient prey capture, but rather are probably used in some specific situations. Vocalisations could potentially be used in response to a prey escaping or showing avoidance behaviour (Handley et al, 2018). For example, in one instance we recorded a King penguin successively emitting three vocalisations in what seemed like a repeated prey capture attempt (Video S4).…”

Section: Underwater Vocalisations For Capturing Prey?mentioning

confidence: 99%

First evidence of underwater vocalisations in hunting penguins

Thiebault

Charrier

Aubin

et al. 2019

PeerJ

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Seabirds are highly vocal on land where acoustic communication plays a crucial role in reproduction. Yet, seabirds spend most of their life at sea. They have developed a number of morphological, physiological and behavioural adaptations to forage in the marine environment. The use of acoustic signals at sea could potentially enhance seabirds’ foraging success, but remains largely unexplored. Penguins emit vocalisations from the sea surface when commuting, a behaviour possibly associated with group formation at sea. Still, they are unique in their exceptional diving abilities and feed entirely underwater. Other air-breathing marine predators that feed under water, like cetaceans, pinnipeds and marine turtles, are known to emit sound underwater, but such behaviour has not yet been described in seabirds. We aimed to assess the potential prevalence and diversity of vocalisations emitted underwater by penguins. We chose three study species from three different genera, and equipped foraging adults with video cameras with built-in microphones. We recorded a total of 203 underwater vocalisation from all three species during 4 h 43 min of underwater footage. Vocalisations were very short in duration (0.06 s on average), with a frequency of maximum amplitude averaging 998 Hz, 1097 Hz and 680 Hz for King, Gentoo and Macaroni penguins, respectively. All vocalisations were emitted during feeding dives and more than 50% of them were directly associated with hunting behaviour, preceeded by an acceleration (by 2.2 s on average) and/or followed by a prey capture attempt (after 0.12 s on average). The function of these vocalisations remain speculative. Although it seems to be related to hunting behaviour, these novel observations warrant further investigation.

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“…Previous studies have highlighted conflicting outcomes of group behaviour on foraging success. For example, where some species may be seen to benefit from group foraging due to information transfer or prey capture facilitation (Thiebault et al, 2014) others suggest that group foraging is just a response to the spatially aggregated prey, leading to intra-specific competition (Handley et al, 2018;Sutton, Hoskins & Arnould, 2015). While group foraging is thought to benefit some, less is known about how multi-predator feeding associations may influence prey capture success.…”

Section: Introductionmentioning

confidence: 99%

Multi-predator assemblages, dive type, bathymetry and sex influence foraging success and efficiency in African penguins

Sutton

Pichegru

Botha

et al. 2020

PeerJ

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Marine predators adapt their hunting techniques to locate and capture prey in response to their surrounding environment. However, little is known about how certain strategies influence foraging success and efficiency. Due to the miniaturisation of animal tracking technologies, a single individual can be equipped with multiple data loggers to obtain multi-scale tracking information. With the addition of animal-borne video data loggers, it is possible to provide context-specific information for movement data obtained over the video recording periods. Through a combination of video data loggers, accelerometers, GPS and depth recorders, this study investigated the influence of habitat, sex and the presence of other predators on the foraging success and efficiency of the endangered African penguin, Spheniscus demersus, from two colonies in Algoa Bay, South Africa. Due to limitations in the battery life of video data loggers, a machine learning model was developed to detect prey captures across full foraging trips. The model was validated using prey capture signals detected in concurrently recording accelerometers and animal-borne cameras and was then applied to detect prey captures throughout the full foraging trip of each individual. Using GPS and bathymetry information to inform the position of dives, individuals were observed to perform both pelagic and benthic diving behaviour. Females were generally more successful on pelagic dives than males, suggesting a trade-off between manoeuvrability and physiological diving capacity. By contrast, males were more successful in benthic dives, at least for Bird Island (BI) birds, possibly due to their larger size compared to females, allowing them to exploit habitat deeper and for longer durations. Both males at BI and both sexes at St Croix (SC) exhibited similar benthic success rates. This may be due to the comparatively shallower seafloor around SC, which could increase the likelihood of females capturing prey on benthic dives. Observation of camera data indicated individuals regularly foraged with a range of other predators including penguins and other seabirds, predatory fish (sharks and tuna) and whales. The presence of other seabirds increased individual foraging success, while predatory fish reduced it, indicating competitive exclusion by larger heterospecifics. This study highlights novel benthic foraging strategies in African penguins and suggests that individuals could buffer the effects of changes to prey availability in response to climate change. Furthermore, although group foraging was prevalent in the present study, its influence on foraging success depends largely on the type of heterospecifics present.

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Behaviourally mediated predation avoidance in penguin prey:in situevidence from animal-borne camera loggers

Cited by 26 publications

References 41 publications

Applications of digital imaging and analysis in seabird monitoring and research

Applications of digital imaging and analysis in seabird monitoring and research

First evidence of underwater vocalisations in hunting penguins

Multi-predator assemblages, dive type, bathymetry and sex influence foraging success and efficiency in African penguins

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