Play it again: the use of video records in behavioural studies with small cetaceans

Some difficulties arise in studying the behaviour of marine mammals at their natural habitat mainly because they spend most of their time underwater and have complex behaviours. Therefore, many protocols and sample methods are available to better assess the behavioural ecology of this animals. Here, we compared two behavioural recording methods. The first one was the direct visual observation. The second one was recording using a digital video recorder. We hypothesise that the possibility of watching recorded videos repeatedly leads to a higher quantification of behaviours compared with the direct observation method. We found a slight variation in the frequency of behaviours according to the method used. Furthermore, we found that the video recordings should not be used as a replacement for the direct observation method. Finally, we highlighted the strengths and weaknesses of both methods. We recommend that in behavioural research, the use of video recording should be careful; it is preferable that an experienced researcher uses the direct observation method, while it is best for a person with low know–how to the use the video recording method.