First Unmanned Aerial Vehicle Observation of Epimeletic Behavior in Indo-Pacific Humpback Dolphins

Abstract

Epimeletic behavior has been reported in various species of cetaceans and sometimes in wild populations during vessel-based surveys. Epimeletic behavior in cetaceans involves complex social interactions which have been described using observational and acoustic studies. The recent advances in unmanned aerial vehicle (UAV) technology allowed its application in wildlife research and frequently in cetaceans in conjunction with vessel-based surveys. This article is the first report of intraspecific epimeletic behavior of Indo-Pacific humpback dolphins (Sousa chinensis) in Hong Kong waters using a combination of UAV- and vessel-based photography. Using both techniques, we were able to observe and qualitative analyze the individual body condition, group behavior, and swimming pattern during the epimeletic event. This study highlighted that UAVs can be used to observe the complex social behaviors and interactions of cetaceans from the aerial angle while keeping a minimal level of disturbance to the animals. Aerial footage can also be quantitatively analyzed to provide further insights on the group behaviors of cetaceans. The application allows efficient assessment of health, behavior, and ecology of wild animals, offering valuable opportunities for researchers working on free-ranging populations.

Unmanned Aerial Vehicles (UAVs) in Marine Mammal Research: A Review of Current Applications and Challenges

“…Megaptera novaeangliae [45,46] Balaenoptera physalus [47] Grampus griseus [48] Tursiops truncatus [49] Lagenorhynchus obscurus [50,51] Sousa chinensis [52] Habitat study Phoca vitulina [53] DJI Phantom 4 Pro…”

“…Moreover, the aerial perspective offers the possibility of observing subsurface behaviours, leading to more accurate interpretations of behavioural states and monitoring of animal movements, which reduces the likelihood of losing sight of target individuals [31,45,[48][49][50]65,102,127,135]. This advantageous perspective also allows for research on poorly studied behaviours, such as the reproductive behaviours of dugongs [108] or epimeletic behaviour in cetaceans [52], as well as observations of previously undocumented behaviours, like synchronous lunge-feeding of humpback whale mother-calf pairs [46] or pilot whale placental expulsion [146]. However, the success of this approach depends on several factors such as the depth of dives, water clarity, and the angle of the sunlight [31,50,74,127].…”