Mattern Thomas, McPherson Michael D, Ellenberg Ursula, van Heezik Yolanda, Seddon Philipp J
Department of Zoology, University of Otago, Dunedin, Otago, New Zealand.
Global Penguin Society, Puerto Madryn, Chubut, Argentina.
PeerJ. 2018 Sep 19;6:e5459. doi: 10.7717/peerj.5459. eCollection 2018.
Camera loggers are increasingly used to examine behavioural aspects of free-ranging animals. However, often video loggers are deployed with a focus on specific behavioural traits utilizing small cameras with a limited field of view, poor light performance and video quality. Yet rapid developments in consumer electronics provide new devices with much improved visual data allowing a wider scope for studies employing this novel methodology. We developed a camera logger that records full HD video through a wide-angle lens, providing high resolution footage with a greater field of view than other camera loggers. The main goal was to assess the suitability of this type of camera for the analysis of various aspects of the foraging ecology of a marine predator, the yellow-eyed penguin in New Zealand. Frame-by-frame analysis allowed accurate timing of prey pursuits and time spent over certain seafloor types. The recorded video footage showed that prey species were associated with certain seafloor types, revealed different predator evasion strategies by benthic fishes, and highlighted varying energetic consequences for penguins pursuing certain types of prey. Other aspects that could be analysed were the timing of breathing intervals between dives and observe exhalation events during prey pursuits, a previously undescribed behaviour. Screen overlays facilitated analysis of flipper angles and beat frequencies throughout various stages of the dive cycle. Flipper movement analysis confirmed decreasing effort during descent phases as the bird gained depth, and that ascent was principally passive. Breathing episodes between dives were short (<1 s) while the majority of the time was devoted to subsurface scanning with a submerged head. Video data recorded on free-ranging animals not only provide a wealth of information recorded from a single deployment but also necessitate new approaches with regards to analysis of visual data. Here, we demonstrate the diversity of information that can be gleaned from video logger data, if devices with high video resolution and wide field of view are utilized.
摄像记录器越来越多地用于研究自由放养动物的行为特征。然而，通常在部署视频记录器时，会利用视野有限、光线性能差和视频质量不佳的小型摄像机，专注于特定的行为特征。不过，消费电子产品的快速发展提供了视觉数据有很大改进的新设备，为采用这种新方法的研究提供了更广阔的空间。我们开发了一种摄像记录器，它通过广角镜头记录全高清视频，提供高分辨率的画面，视野比其他摄像记录器更宽。主要目标是评估这种类型的摄像机对于分析海洋捕食者——新西兰黄眼企鹅觅食生态各个方面的适用性。逐帧分析能够准确记录捕食猎物的时间以及在特定海底类型上花费的时间。记录的视频画面显示，猎物种类与特定海底类型相关联，揭示了底栖鱼类不同的躲避捕食者策略，并突出了企鹅追捕某些类型猎物时不同的能量消耗后果。其他可以分析的方面包括潜水之间呼吸间隔的时间，以及观察捕食猎物时的呼气事件，这是一种以前未被描述过的行为。屏幕叠加有助于分析潜水周期各个阶段的鳍部角度和拍打频率。鳍部运动分析证实，随着企鹅下潜深度增加，下降阶段的用力逐渐减少，且上升主要是被动的。潜水之间的呼吸时间很短（<1秒），而大部分时间用于头部浸没在水下进行海面下扫描。记录自由放养动物的视频数据不仅从单次部署中提供了丰富的信息，而且在视觉数据分析方面也需要新的方法。在这里，我们展示了如果使用具有高分辨率和宽视野的设备，可以从视频记录器数据中收集到的信息的多样性。
