How Fishing Cats Prionailurus viverrinus fish: Describing a felid's strategy to hunt aquatic prey

Abstract

Hunting strategies are key to carnivore survival (Krebs and Davies 2009;Kamil et al. 2012;Michalko and Pekar 2016). Fishing Cats (Prionailurus viverrinus) persistence in the semi-aquatic niche (Kitchener et al. 2010) despite felids being terrestrial carnivores in general (>95%) (Hunter 2019) suggests the evolution of a successful hunting strategy. Its further suggest selection for hunting in wetlands. What energy conserving strategies did the Fishing Cat borrow from its family and how were these adapted to optimize energy gained from hunting fish, its primary prey? We attempt to answer this by analyzing 197 video footages collected opportunistically from a participatory science initiative conducted over 2.5 years. We found that the felid switches between stationary and active modes of searching for prey depending on the depth of water and the corresponding loss of body heat/energy. For example, diving in deeper waters requires the submergence of the upper portions of the body and loss of more body heat/energy. Our analysis shows that the cat spent much of its time (~52%) sitting and waiting for prey (fish) to come nearer and then took limited attempts to dive into deeper water (2.78%). We suggest that this is a strategy to optimize the net energy gain. In shallow waters where the cat could forage without submerging the upper body it adopted a predominantly active mode of hunting (~96%) to flush out prey. Thus, prominent hunting strategies in the small cat lineage like sit-and-wait and active foraging is adapted to hunt in the water. We recorded a 60% hunting success in deeper waters but did not detect a successful hunt in shallow waters due to the low sample size of data from shallow water hunting. The major caveat in our study is the post-hoc analysis of opportunistically collected data as opposed to data derived from a structured design with predefined objectives. With more sampling from various seasons and landscapes, finer details can be explored which would have conservation implications. For example, we would expect variations in attempts to hunt during cold seasons because heat loss might be less of a challenge in the latter. Quantifying attempts to hunt and successful hunts across seasons could help focus management interventions to minimize negative interactions between fish cultivators and Fishing Cat. The strictly nocturnal activity of fishing cat as demonstrated in our study could be a strategy taken by the cat to avoid humans. Our approach of using participatory-science is relevant for conducting research on mammal behavior in human dominated landscapes.