Those of us who co-occur with domestic felids either in the capacity of pets or tolerate their occasional visits to our abodes, know about their great affinity for fish. But we also know that they hate water and the thought of getting wet. So, they would never venture into water despite finding fishes palatable. This is so for most cats in the animal kingdom except, perhaps, for the tiger and the Pantanal jaguar. But again, in neither of them exist physical adaptations suited to rule the habitat that exists at the junction of land and water – wetlands.
Out of about 40 wild cat species, nature has cherry-picked and bestowed characteristic features on just two cats, to enable them to colonise and thrive in wetlands – one is the flat-headed cat, endemic to Southeast Asia and the other is the fishing cat which is distributed in parts of South and Southeast Asia. In India, the fishing cat (Prionailurus viverrinus) is majorly found in the floodplains of major rivers such as Ganga and Brahmaputra and in mangroves and coastal deltas along India’s eastern coast . In a family that otherwise dominates our imagination as magnificent terrestrial predators, fishing cat stands out as a fascinating anomaly. It has partial webbing in its paws like a duck and a coat that is double-layered enabling the skin underneath to stay dry even when hunting fish.
A fishing cat caught on a camera trap. The fishing cat boasts of unique physical adaptations that help it thrive in wetland habitats. Photo credit: The Fishing Cat Project
So how exactly does the fishing cat hunt? Does it dive underwater submerging the body completely while going after schools of fishes? Does it disappear like a grebe only to resurface meters away? Our research suggests that the fishing cat has effectively learnt the traditional techniques of hunting from its felid counterparts in the course of evolution. Small cats hunt on terra firma in two ways – they lie in ambush waiting for the prey to venture close enough to catch it by surprise (the sit-and-wait strategy), or they actively flush out the prey before attempting to catch it. But, the fishing cat has modified these techniques to suit a semi-aquatic lifestyle.
A fishing cat typically waits at the water’s edge and plunges its forepaws or mouth first into the water to catch fish while anchoring its hind-legs into the mud. Or it dives into the water to catch the fish, which wets its upper body. During such hunts, these cats spend most of their time sitting in a location waiting for fish to come close and then after a certain period of time will move to a different location only to ‘sit and wait’ again.
They spend roughly 52 percent of their time sitting and waiting and about 38 percent of their time patrolling all possible hunting locations. They continue to move between water bodies in their territory until they detect movement in water, and only when they are very certain of making a kill do they launch an attack, which accounts for only four percent of the total time invested in hunting. Such a strategy that involves devoting a very small percentage of time to attacking tells us that they want to conserve energy because with each plunge the body’s mechanical energy starts to deplete. In addition, each unsuccessful plunge would also alert the potential prey and scare them away. It is a mental permutation and combination of all these factors which guide the intuition of the fishing cat.
However, like all predators, fishing cats too do not boast of a 100 percent hunting success rate. Imagine what would happen if all predators managed to successfully catch their prey all the time! We found that fishing cats were successful in about half their hunting attempts.
Video credit: The Fishing Cat Project
Now, the question is why would such a hunting strategy be supported by natural evolution? Why would a wild cat belonging to a family of marvelously successful terrestrial hunters evolve to catch fish? Furthermore, small cats get maximum metabolisable energy from rodents. Fishing cat, being a small cat, still prefers fish over rodents. Why? For this we need to tease apart and balance the costs associated with hunting at each stage. The ‘sit-and-wait’ approach to hunt prey has been adopted by many felids in the pre-kill stage as an energy conserving strategy, which also increases the probability of successfully ambushing unwary prey. Post-kill stages of fish consumption include subduing prey, processing, consuming, and digesting. Once caught, fish are easy to subdue compared with terrestrial prey. Additionally, there is minimal cost of processing fish kills. Imagine how much time would go into peeling off feathers to actually get to the bird meat. In case of a rodent kill, its fur and bones would have to be processed internally which again costs energy. In comparison, fish protein is easily digestible and unprocessed fish scales are simply excreted out as undigested matter.
All these findings have emerged from our sustained studies conducted over many years in human-dominated landscapes – mainly in three study sites including Howrah District in the lower Gangetic floodplains of West Bengal and two coastal wetlands in the Mahanadi floodplains along the eastern coast – Paradip and Chilika. Uniquely, we resorted to gathering data through a citizen-science initiative. The participatory conservation initiative is called ‘Know Thy Neighbours’ in which residents sharing space with fishing cats were engaged in documenting and monitoring the cats in their backyards using camera traps.
Going forward, hunting success rates need to be examined in various seasons. For example, during winter, fishes become inactive. How does that affect the fishing cats? In contrast, summers provide wonderful foraging opportunities when oxygen levels drop in the waters at night and fish frequently surface. Understanding this aspect of the fishing cat’s behaviour will help develop relevant and more effective human-fishing cat conflict mitigation measures, as sometimes fishing cats and small-scale fish farmers do get into conflict with each other.
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About the Authors:
Tiasa Adhya is the co-founder of The Fishing Cat Project, a partner to the Fishing Cat Conservation Alliance and a member of the IUCN Species Survival Commission.
Divyajyoti Ganguly is pursuing his postgraduate degree in Wildlife Biology and Conservation from National Centre for Biological Sciences, Bengaluru, India.
Disclaimer: The views and opinions expressed in the article are the authors’ own and do not necessarily reflect the views and opinions of Wildlife Conservation Trust.
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