- Sri Lanka’s largest city, Colombo, is home to the only known urban population of fishing cats throughout their global range.
- Using tracking data, scientists are studying how these felines, about twice the size of a domestic cat, are navigating this built-up environment in one of the most densely populated cities on Earth.
- They’ve found that the urban cats have a smaller range than their rural counterparts, and raid fish ponds and poultry pens for food.
- The adaptability of Colombo’s fishing cats has given researchers optimism about the species’ survival in an increasingly urbanized world, but further studies will be needed to aid in their conservation.
COLOMBO — At his home in Thimbirigasyaya, a highly residential area in the heart of Sri Lanka’s commercial capital Colombo, Eshan Witana keeps expensive Japanese koi fish, a species of carp (Cyprinus rubrofuscus), in a pond.
But to his dismay, these fish started to disappear after nightfall. So he set up security cameras trained on the pond, and soon identified the thief: a young fishing cat, Prionailurus viverrinus.
Recognizing the opportunity to study the behavior of this wild cat in an urban setting, Anya Ratnayaka of the Urban Fishing Cat Conservation Project started stocking Tudawe’s pond with less expensive fish. A few weeks later, the same fishing cat got stuck in a nearby drainpipe and was rescued by a team from Sri Lanka’s Department of Wildlife Conservation (DWC).
Conservation officials fitted the cat with a radio collar before releasing it. Over the next six months, until the collar fell off, the tracker would provide valuable data about the cat’s movements. It showed, Ratnayaka found, that the cat made use of built-up areas and canal systems in this busy area to lie low. It also showed the cat sheltering by day in human structures, even in the attics of houses.
“The closest wetland to the location is about 4.5 kilometers [2.8 miles] away, so this fishing cat thrives entirely on this highly urban area,” Ratnayaka told Mongabay. “It is a sub-adult male, so could be pushed into marginal habitat by adults to find in this urban setting.”
Ratnayaka and a team from the DWC also collared four other fishing cats — two translocated cats and two residential cats that now live in the 24-hectare (59-acre) Diyasaru Park and 449-hectare (1,110-acre) Jayawardenapura Wetland Sanctuary in Colombo — to learn about how these felines, twice the size of a domestic cat, survive in one of the most densely populated cities on Earth.
“To our knowledge, this is the first fishing cat-focused GPS collar study in an urban landscape,” Ratnayaka said.
Resourceful fishing cats
Ratnayaka and her fellow researchers recently published the results of their 2013-2019 tracking efforts. Among the key findings: urban fishing cats have a smaller home range than rural ones, and females have the smallest ranges of all, possibly due to a preference for a safer known habitat closer to food sources to raise their young.
The fishing cat, as its name suggests, is a wetland-dependent species, but the study found that Colombo’s urban fishing cats spend more time in built-up areas than in wetlands. Here, too, the tendency is more pronounced among males of the species.
By day, they appear to favor wetland habitats, and by night venture into human-modified urban areas. Ratnayaka said the cats are extremely resourceful and have adapted to urban settings better than previously thought.
“We tend to think animals in natural areas have more food and shelter, but it is not always the case,” she said. “For example, a fishing cat in a typical Sri Lankan jungle would have to compete with the leopard and jackal for food and safety. The saltwater crocodile would be the only natural predator for mature fishing cats in Colombo, and they can find food by expending less energy by catching ornamental fish and birds.”
However, in their quest for food, fishing cats often raid poultry pens, triggering conflict with humans. People are also fearful of fishing cats when they come out at night. Ratnayaka said she takes a lot of time to educate the public about fishing cats through awareness programs to promote co-existence.
Fatal road accidents
The researchers had a heartbreaking moment when one of the translocated animals was run over on an expressway, about 6 km (4 mi) away from its release site, while trying to find its way back to its original home range. The fate of the other translocated cat is unknown after its collar stopped emitting signals six months after being fitted.
“The results also tell us the importance of trying to prevent translocations, and if it cannot be prevented, careful action should be taken such as keeping the fishing cat in a large enclosure where it is to be released, helping them to settle in the area,” Ratnayaka said.
Researchers and residents have long suspected that fishing cats frequent the urban jungle of Colombo. Past reports of “mystery cats” and the occasional accidental killing of fishing cats on the outskirts of the city pointed to that possibility.
The first proper study of Sri Lanka’s fishing cats were conducted by Eric Wikramanayake in the 1990s. His camera traps captured many images of the elusive cats, but the research had to be halted due to security concerns due to the Sri Lankan civil war that only ended in 2009. The main study sites, such as the Sri Jayewardenapura marshes and the Bellanwila-Attidiya wetlands, were located near the country’s parliament and a military airport, respectively, making them prime targets for possible attacks.
Determined to study Colombo’s fishing cats while taking actions to conserve the species, Ratnayaka in 2013 founded the Urban Fishing Cat Conservation Project in Colombo. To confirm the cats’ presence in the city, the team set remote camera traps in selected wetland habits around Colombo, snapping photos of the cats in many different locations.
Colombo was in 2018 accredited as a RAMSAR wetland city, despite losing more than 60% of its wetlands since the 1980s. Its current rate of wetland loss is around 1.2% per year. Ratnayaka said it’s important to protect these remaining wetlands to secure the future of Colombo’s urban fishing cats, though some could adapt to a fully urban setting.
While the species occurs throughout South and Southeast Asia, Colombo is home to the only known urban population of fishing cats.
“But based on our observations,” Ratnayaka said, “it is possible that other urban populations exist elsewhere without getting themselves noticed.”
Citation:
Ratnayaka, A. A. W, Serieys, L. E. K, Prasad, T., Leighton, G. R. M, Sanderson, J. G, & Leung L. K. P. (2021). Urban habitat use and home ranges of fishing cats in Colombo, Sri Lanka. Mammalian Biology. doi:10.1007/s42991-021-00198-z
Banner image of a fishing cat captured at the Royal Colombo Golf Club courtesy of the Urban Fishing Cat Conservation Project.