Dabkowski Owen, Ellenberg Ursula, Mattern Thomas, Pütz Klemens, Garcia Borboroglu Pablo
Department of Marine Science, University of Otago, Dunedin, New Zealand.
The Tawaki Trust, Dunedin, New Zealand.
PeerJ. 2025 Jan 28;13:e18598. doi: 10.7717/peerj.18598. eCollection 2025.
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 (), Tawaki () and King () 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.
使用动物携带的摄像头使科学家能够观察到迄今为止未被看到或很少被记录的行为和互动。研究人员现在可以更详细地分析猎物偏好和捕食者与猎物的互动。新技术使研究人员能够在猎物被捕获之前分析其特征，为现有的猎物分析技术增添了新的维度，而现有技术主要依靠通过洗胃检查部分或完全消化的猎物。为了确定猎物的大小，拍摄的视频片段需要一个校正因子（像素：毫米比率），使研究人员能够使用图像测量软件测量猎物尺寸并将像素转换为实际测量值。这反过来将有助于估计猎物的能量含量。这种方法需要一个具有已知尺寸的参考物体（如喙的测量值）来确定你的距离的实际情况。使用企鹅摄像头，我们通过在不同盐度（从空气和淡水到高达35 psu，以5 psu为增量）、控制温度和压力的情况下，从在已知距离（10、20、30、40、50、60厘米）拍摄的视频片段中测量1毫米网格纸的2厘米部分，确定了校正因子。我们发现不同盐度的水的校正因子之间没有显著差异。然而，由于它们在折射率上有相当大的差异，水和空气之间的校正因子存在差异。根据测试距离的校正因子建立的线性方程有助于预测测试距离之间的校正因子，因此能够更广泛地应用这项研究。我们提供了从洪堡企鹅、塔瓦基企鹅和王企鹅的企鹅摄像头视频片段中获取的例子，以说明所确定的校正因子的使用。这项研究为研究人员提供了一个工具，以进一步增强他们对捕食者与猎物互动的理解。
