{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,1,29]],"date-time":"2025-01-29T05:32:27Z","timestamp":1738128747867,"version":"3.33.0"},"reference-count":39,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2025,1,28]],"date-time":"2025-01-28T00:00:00Z","timestamp":1738022400000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Marine Science Department Summer Research Bursary","award":["UO-00701437"],"award-info":[{"award-number":["UO-00701437"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>The use of animal-borne cameras enables scientists to observe behaviours and interactions that have until now, gone unseen or rarely documented. Researchers can now analyse prey preferences and predator-prey interactions with a new level of detail. New technology allows researchers to analyse prey features before they are captured, adding a new dimension to existing prey analysis techniques, which have primarily relied on examining partially or fully digested prey through stomach flushing. To determine prey size, the video footage captured needs a correction factor (pixel:mm ratio) that allows researchers to measure prey dimensions using image measuring software and convert the pixels to actual measurements. This in turn will help estimating the prey energy content. This method requires a reference object with known dimensions (such as beak measurements) to ground truth your distance. Using PenguCams we determined the correction factor by measuring a 2 cm section of 1 mm grid paper from video footage taken at known distances (10, 20, 30, 40, 50, 60 cm) in different salinities ranging from air and fresh water, up to 35 psu in 5 psu increments while controlling for temperature and pressure. We found no significant difference between correction factors of water at different salinities. However, due to their considerable differences in refraction index, correction factors contrast between water and air. Linear equations modelled from correction factors at tested distances help predict correction factors between tested distances and, therefore, enable a wider application of this research. We provide examples from PenguCam footage taken of Humboldt (<jats:italic>Spheniscus humboldti<\/jats:italic>), Tawaki (<jats:italic>Eudyptes pachyrhynchus<\/jats:italic>) and King (<jats:italic>Aptenodytes patagonicus<\/jats:italic>) penguins to illustrate the use of identified correction factors. This study provides a tool for researchers to further enhance their understanding of predator-prey interactions.<\/jats:p>","DOI":"10.7717\/peerj.18598","type":"journal-article","created":{"date-parts":[[2025,1,28]],"date-time":"2025-01-28T08:00:27Z","timestamp":1738051227000},"page":"e18598","source":"Crossref","is-referenced-by-count":0,"title":["Correction factors for prey size estimation from PenguCams"],"prefix":"10.7717","volume":"13","author":[{"given":"Owen","family":"Dabkowski","sequence":"first","affiliation":[{"name":"Department of Marine Science, University of Otago, Dunedin, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ursula","family":"Ellenberg","sequence":"additional","affiliation":[{"name":"Department of Marine Science, University of Otago, Dunedin, New Zealand"},{"name":"The Tawaki Trust, Dunedin, New Zealand"},{"name":"Global Penguin Society, Chubut, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thomas","family":"Mattern","sequence":"additional","affiliation":[{"name":"The Tawaki Trust, Dunedin, New Zealand"},{"name":"Global Penguin Society, Chubut, Argentina"},{"name":"Department of Zoology, University of Otago, Dunedin, New Zealand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Klemens","family":"P\u00fctz","sequence":"additional","affiliation":[{"name":"Antarctic Research Trust, c\/o Z\u00fcrich, Z\u00fcrich, Switzerland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Pablo","family":"Garcia Borboroglu","sequence":"additional","affiliation":[{"name":"The Tawaki Trust, Dunedin, New Zealand"},{"name":"Global Penguin Society, Chubut, Argentina"},{"name":"Centro Nacional Patag\u00f3nico (CONICET), Chubut, Argentina"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"4443","published-online":{"date-parts":[[2025,1,28]]},"reference":[{"key":"10.7717\/peerj.18598\/ref-1","doi-asserted-by":"publisher","first-page":"211","DOI":"10.1007\/978-3-031-24097-3_9","article-title":"Refraction","volume-title":"Light and waves: a conceptual exploration of physics","author":"Andrews","year":"2023"},{"key":"10.7717\/peerj.18598\/ref-2","article-title":"gridExtra: miscellaneous functions for grid graphics","author":"Auguie","year":"2017","edition":"2.3"},{"key":"10.7717\/peerj.18598\/ref-3","doi-asserted-by":"publisher","DOI":"10.21236\/ada024800","volume-title":"The index of refraction of seawater","author":"Austin","year":"1976"},{"issue":"3","key":"10.7717\/peerj.18598\/ref-4","doi-asserted-by":"publisher","first-page":"555","DOI":"10.12928\/telkomnika.v9i3.748","article-title":"An approach to minimising estimated pincushion camera distortions","volume":"9","author":"Ayinde","year":"2011","journal-title":"Telecommunication Computing Electronics and Control"},{"issue":"2","key":"10.7717\/peerj.18598\/ref-5","doi-asserted-by":"publisher","first-page":"305","DOI":"10.1093\/icb\/45.2.305","article-title":"Physiological ecology in the 21st century: advancements in biologging science","volume":"45","author":"Block","year":"2005","journal-title":"Integrative and Comparative Biology"},{"issue":"8","key":"10.7717\/peerj.18598\/ref-6","doi-asserted-by":"publisher","first-page":"1626","DOI":"10.1111\/1365-2435.13605","article-title":"Quantifying prey availability using the foraging plasticity of a marine predator, the little penguin","volume":"34","author":"Cavallo","year":"2020","journal-title":"Functional Ecology"},{"issue":"7","key":"10.7717\/peerj.18598\/ref-7","doi-asserted-by":"publisher","first-page":"106","DOI":"10.1007\/s00227-021-03916-w","article-title":"Ancillary data from animal-borne cameras as an ecological survey tool for marine communities","volume":"168","author":"Chapple","year":"2021","journal-title":"Marine Biology"},{"key":"10.7717\/peerj.18598\/ref-8","doi-asserted-by":"publisher","first-page":"92","DOI":"10.3389\/fevo.2018.00092","article-title":"Biologging physiological and ecological responses to climatic variation: new tools for the climate change era","volume":"6","author":"Chmura","year":"2018","journal-title":"Frontiers in Ecology and Evolution"},{"key":"10.7717\/peerj.18598\/ref-9","article-title":"Seeing the sea through the eyes of Humboldt penguins - 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