Unnatural Predators in a New Urban Ecosystem – The Wire Science


Stray dogs invaded a hallway leading to a university block inside IIT Madras. Photo: Prakriti (IIT Madras animal club)

  • In the six decades since much of IIT Madras was carved out of the Guindy Forest, the number of people living on campus has increased by an order of magnitude.
  • The resulting ‘urbanization’ has degraded the habitat of chitals, bonnet macaques, blackbucks and monitor lizards and led to the spread of invasive species of flora and fauna.
  • With the growing human presence has come an increase in the number of free-roaming domestic dogs on campus, and they have become a threat to campus wildlife.
  • They are not predators per se as their numbers are disproportionately greater than their “prey”.
  • Instead, the dogs are killers, with a population sustained by human activities and their wandering the streets and forests justified by a poor understanding of ecology.

“There is certainly nothing abnormal 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 in which we live. Urban landscapes cannot be simplistically mapped onto natural landscapes. Their complex aggregation of species – alien, invasive and natural – is adapted to severely modified urban habitats.

Free-roaming domestic dogs may have adapted to food waste in modern cities and particularly emerged as predators of remaining wildlife in the Guindy Forest of Chennai. Yet these are not desirable predators that are needed to sustain the chital population (axis axis) in check. They’re not even natural predators, but that’s not the argument.

It is that they are a nuisance and disturb the urban ecosystem, and therefore undesirable. The laws of the land need to be changed and wrapped around this reality. Nor does the fact that dogs took a commensal1 route to domestication justify their existence as scavengers on the streets of our cities.

Habitat degradation

In the six decades since much of IIT Madras was carved out of Guindy Forest (a reserve forest), the number of people living on campus has increased by an order of magnitude. But the infrastructure that supports their life and work has come at the expense of the campus’ unique biodiversity legacy. The built-up area of ​​IIT Madras, which is within the environmentally sensitive area of ​​Guindy National Park (GNP), is today approximately 0.5 km2.

This ‘urbanization’ has degraded the habitat of chitals, bonnet macaques (Macaca written off), fallow deer (Antelope cervicapra) and monitor lizards (Varanus bengalensis) – to name only the large animals registered on campus – and has led to the spread of invasive species of flora and fauna. “If you look at the photography of the area from the 1960s, there were only palm trees (Borassus flabelliferae) palms, thickets and grasslands,” said Ranjit Daniels, administrator of Care Earth, an NGO. “The trees are mostly planted and a lot of them aren’t even native. Also, the invasive Prosopis took over this area. »

Prosopis juliflora is a shrubby plant that has been recognized as an invasive species on several continents.

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

Wild animals and domestic dogs

IIT Madras tried to contain the domestic dog population through the Animal (dog) Birth Control (ABC) program, but it did not work. In fact, over the past two decades, evidence has accumulated to show that the Indian government’s “official” ABC program has not worked anywhere in the country.

The logic of the catch-neutral-release (CNR) policy has failed not only because of poor implementation, but because of its very design, which goes against 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 free-roaming dog population. As such, there is a need to repeal this unscientific dog management policy – ​​which has also led to multiple complaints being filed against her in the Supreme Court.

At the end of 2020, the management of IIT Madras removed the loose dogs to enclosures. But an NGO named People For Cattle In India filed a Public Interest Litigation (PIL) claiming “the plight of dogs” against the institute in the Madras High Court. However, the court granted relief to IIT, which had requested that all dogs be removed from campus. The court also ordered the relevant state authorities to “ensure that the IITM is cleared of the threat.”

The Prakriti Wildlife Club, formed by members of the resident engineering community at the IIT Madras campus, has also advocated against the threat of dogs on the campus. They tried to implement ABC methods that “didn’t work due to the continuous influx of outside dogs onto campus,” said Susy Varughese, Prakriti member and professor in the chemical engineering department. .

“Stray dog ​​lovers have brought dogs from elsewhere and released them onto campus.”

According to her, Prakriti has also tried to eliminate food waste on campus, on which dogs thrive, and to “protect dogs” from entry points.

Varughese was delighted with the High Court’s order and its implications for wildlife on campus. “We have a great experience with results to show. For the record, nine of 11 blackbuck fawns survived this season after the strays were removed,” she said. “It was one or two in all those years.”

The need for natural predators

Domestic dogs are known to be a threat to at least 80 species, including 31 in the Indian subcontinent that are listed as ‘threatened’ on the IUCN Red List. Despite this awareness, however, these dogs have not been recognized as a invasive species in India.

Even locally, in the small isolated forest of Guindy, the survival of the blackbuck population – which enjoys the highest level of protection offered by the Wildlife (Protection) Act 1972 – is threatened by domestic dogs. There is therefore a strong ecological reason for the scientific community to propose that domestic dogs be declared “invasive” and that all policy recommendations on Guindy forests be written based on this evidence.

In the Guindy Forest – which is now fragmented into two parts of the IIT Madras campus and Guindy National Park – free range domestic dogs are thriving as there is plenty of food waste to feed on. But they also exist in such large numbers because of the poor population control policy.

“The ABC program does not work at all, and to say that sterilization reduces their aggression is nonsense. “Even rage control is not effective,” Daniels said. “In the absence of natural predators, dogs became the predators.”

At the same time, calling dogs “predators” in a scenario where predator and prey populations are so disproportionate doesn’t make ecological sense. In other words, dogs are not quite predators in the sense of the term vis-à-vis a system in which populations of predators and prey co-evolve and mutually regulate each other.

For example, if there are a lot of worms in an area, many birds will come and eat them. The bird population will therefore increase over time, but this will lead to overfeeding of the worms. Eventually, the number of worms will decrease and also reduce the bird population. But once there are fewer birds, the number of worms will start to increase again. And so on.

Instead, the dogs are simply marauding killers in Guindy Forest, with their population artificially sustained by human activities and their free roaming of the streets and forests justified by a poor understanding of ecology.

The chital population has yet to be controlled, as Daniels says, and the jackals (golden canis) might be the animals to do so in Guindy Forest. Jackals prey on smaller animals, but these include chital fawns.

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

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-sufficient population.

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


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