Unnatural Predators in a Novel Urban Ecosystem – The Wire Science


Stray dogs have invaded a hallway leading to an academic block inside IIT Madras. Photo: Prakriti (IIT Madras wildlife club)


  • In the six decades since a large part of IIT Madras was carved out of the Guindy forest, the number of people living on the campus has increased by an order of magnitude.
  • The resulting ‘urbanisation’ has degraded the habitat of chitals, bonnet macaques, blackbucks and monitor lizards and has lead to the spread of invasive species of flora and fauna.
  • The expanding human presence has accompanied an increase in the number of free-ranging domestic dogs on campus, and they have become a threat to the campus wildlife.
  • They are not predators per se because their numbers are disproportionately higher than they ‘prey’.
  • Instead, dogs are killers, with a population supported by anthropogenic activities and their free-roaming in the streets and forests justified by a faulty understanding of ecology.

“Certainly nothing is unnatural that is not physically impossible,” said Richard Brinsley Sheridan in the 18th century – and most certainly nature is malleable. But it is important to pay attention to the underlying principles of ecology when we modify, compose and recompose the environment we live in. Urban landscapes cannot be simplistically mapped onto natural landscapes. Their complex species aggregation – of exotics, invasive and natural – is adapted to severely modified urban habitats.

Free-ranging domestic dogs may well have adapted to the food waste in modern cities, and specifically have emerged as predators of remnant wildlife in Chennai’s Guindy forest. Yet they are not desirable predators that are required to keep the population of chital (Axis axis) in check. They are not even natural predators, but that is not the argument.

It is that they are a nuisance and disruptive to the urban ecosystem, and thus undesirable. The laws of the land need to be modified and wrapped around this reality. The fact that dogs took a commensal pathway1 to domestication also doesn’t justify their existence as scavengers on our cities’ streets.

Habitat degradation

In the six decades since a large part of IIT Madras was carved out of the Guindy forest (a reserve forest), the number of people living on the campus has increased by an order of magnitude. But the infrastructure supporting their lives and their work has come at the cost of the unique biodiversity legacy of the campus. The built-up area of IIT Madras, which is in the ecologically sensitive area of Guindy National Park (GNP), is today about 0.5 sq. km.

This ‘urbanisation’ has degraded the habitat of chitals, bonnet macaques (Macaca radiata), blackbucks (Antilope cervicapra) and monitor lizards (Varanus bengalensis) – to name just the large animals recorded on campus – and has lead to the spread of invasive species of flora and fauna. “If you look at the photograph of the area from the 1960s, there were only palmyrah (Borassus flabellifer) palms, thickets and grasslands,” Ranjit Daniels, a trustee at Care Earth, an NGO, said. “Trees are mostly planted and many of them are not even native. Also, the invasive Prosopis has taken over this area.”

Prosopis juliflora is a shrub-like plant that has been recognised as an invasive species on multiple continents.

The expanding human presence has accompanied an increase in the number of free-ranging domestic dogs (Canis familiaris) on campus and, predictably, they have become a threat to the campus wildlife. In 2020 alone, free-ranging dogs killed 94 animals, including “75 deer and three blackbucks”.

Wild animals and domestic dogs

IIT Madras did make an attempt to contain the population of domestic dogs through the Animal (dog) Birth Control (ABC) programme, but it did not work. In fact, in the last two decades, evidence has accumulated to demonstrate that the Indian government’s ‘official’ ABC programme hasn’t worked anywhere in the country.

The policy’s logic of catch-neutre-release (CNR) has failed not merely because of poor implementation but because of its very design, which runs counter to the principles of population dynamics.

A 2020 modeling study established that even in the best-case scenario, the CNR approach is not likely to yield the desired level of control over the population of free-ranging dogs. As such, there is a need to abrogate this unscientific dog management policy – which has also led to the filing of multiple cases against it in the Supreme Court.

Sometime in late 2020, the IIT Madras management removed free-ranging dogs to enclosures. But an NGO named People For Cattle In India filed a public interest litigation (PIL) that complained “of the plight of dogs” against the institute in Madras high court. However, the court provided relief to the IIT, which had asked for all the dogs to be removed from the campus. The court also ordered the relevant state authorities to “ensure that IITM is rid of the menace”.

The wildlife club Prakriti, formed by members of the resident community of engineers on the IIT Madras campus, has also been advocating against the dog menace on campus. They tried to implement ABC methods that “did not work because of the continuous inflow of dogs from outside into the campus,” said Susy Varughese, a member of Prakriti and a professor in the department of chemical engineering.

“Stray dog enthusiasts brought dogs from elsewhere and released them on the campus.”

According to her, Prakriti has also tried to eliminate food waste on the campus, which the dogs thrive on, and to “dog-proof” the points of entry.

Varughese was elated by the high court’s order and its implications for the campus’s wild animals. “We have a beautiful experiment with results to show. For the record, we had nine out of 11 blackbuck fawns surviving this season after stray dogs were removed,” she said. “It used to be one or two in all these years.”

The need for natural predators

Domestic dogs are known to be a threat for at least 80 species, including 31 in the Indian subcontinent that are classified as being ‘threatened’ on the IUCN Red List. In spite of this awareness, however, these dogs have not been recognised as an invasive species in India.

Even locally, in the small and isolated Guindy forest, the survival of the population of blackbucks – which enjoys the highest level of protection afforded by the Wildlife (Protection) Act 1972 – is threatened by domestic dogs. So there exists a strong ecological reason for the scientific community to propose that domestic dogs be declared ‘invasive’ and for all policy recommendations on Guindy forests to be drafted in keeping with this evidence.

In the Guindy forest – which is now fragmented into the two chunks of the IIT Madras campus and the Guindy National Park – free-ranging domestic dogs flourish because there is plenty of food waste to feed on. But they also exist in such large numbers because of the bad population-control policy.

“The ABC programme is not at all working, and to say that sterilisation reduces their aggressiveness is nonsense. “Even rabies-control is not effective,” Daniels said. “In the absence of natural predators, dogs have emerged as the predators.”

At the same time, addressing dogs as ‘predators’ in a scenario in which the populations of predator and prey are so out of proportion does not make ecological sense. That is, dogs are not quite predators as the term means vis-à-vis a system in which predator and prey populations coevolve and mutually regulate each others’ numbers.

For example, if there are many worms in an area, many birds will turn up to eat them. The birds’ population will thus increase in time, but this will lead to over-feeding of the worms. Eventually, the number of worms will decline, and bring down the population of birds as well. But once there are fewer birds, the number of worms will start to increase again. And so forth.

Instead, dogs are simply marauding killers in the Guindy forest, with their population artificially supported by anthropogenic activities and their free-roaming in the streets and forests justified by a faulty understanding of ecology.

The chital population still needs to be kept in check, as Daniels says, and jackals (Canis aureus) could be the animals to do so in the Guindy forest. Jackals feed on smaller animals but those include chital fawns.

“Having a thriving population of jackals in the isolated forest surrounded by a city can be very difficult,” Daniels said. “But if the habitat is restored by bringing back the earlier grassland area, removing the invasive Prosopis and non-native trees and removing dogs that are both direct competition and also spread disease to jackals, then jackals can establish themselves.”

According to him, the IIT Madras campus can hold 10 jackals and the Guindy National Park another 10 jackals. And that, it seems, would be a self-sustaining population.

Narendra Patil has worked for the Wildlife Conservation Society (India) and the Centre for Wildlife Studies for a decade, and with the Snow Leopard Conservancy (India Trust) in Ladakh for two years.



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