Urban Ecosystems: Snakes and the City

I receive a frantic call from a friend in the heart of Mumbai; “there are two huge snakes mating in front of the podium! Come quickly, the building guys may kill them!” He lives in a large society of skyscrapers, where the human density is well over 28,000 people per sq km, 60 times the national average. I rush over to find two six-foot-long rat snakes engaged in male-male combat, which is an act to test dominance and secure rights over access to a mate. This seemingly intimate dance is often misconstrued as mating.

Several Indian cities, both large and small, possess a network of highly motivated people who help in “rescuing” snakes that are found within urban spaces. The standard protocol is to catch the snake, put it in a bag, inform the forest department, and then release the snake in a “suitable habitat” which generally means a nearby forest.

However, a growing number of studies from India and across the world suggest that these urban snakes are not “stray individuals” that have inadvertently surfaced within cities, but rather permanent residents, much like the crows, dogs, rats, sparrows, pigeons, and parakeets. They are reported to be very familiar with the region they inhabit, navigating a network of drains, ditches, rodent holes, sewers, gardens, and trees in order to survive. And they probably perform a very important function of controlling rodent populations in urban spaces.

Though these reptiles could be intimidating for human residents of cities, there is little cause for worry if simple safety precautions are followed. Snakes have no inclination to attack humans for the simple reason that humans are not prey, and they cannot derive any benefit from it. It does not make ecological or economic sense for a snake to attempt attacking a human as that would waste its energy and it runs the risk of injury or death.
Snakes only bite or attack humans in self-defence — that is, only when they feel threatened, such as when they are stepped on or cornered with no escape. Snakes do not have much to do with humans, most species making a quick getaway on being detected, while others such as vipers, freeze in their tracks with the intention of camouflaging and passing undetected.

The “solution”, for people who are averse to having snakes around, is rather simple — make your landscape less attractive for snakes. One question I often encounter is: Why are there snakes in my area? Snakes in a particular area are symptoms or indicators of a suitable habitat for them. This means that if there is a bustling population of prey such as rodents (which are attracted to human habitation by garbage heaps), shelter in the form of discarded bricks, tin sheets, plywood, rodent holes etc., the place is attractive for snakes and they are bound to thrive. Therefore it is not the snakes seeking humans out, but rather humans inviting snakes by creating conducive environments.

An oft-used remedial measure is to “translocate” snakes, that is, pick them up from human habitation and release them in forest habitats where they are “supposed to be”. However, this does not help achieve the goal, because the space is still a good habitat for snakes, and will be occupied by another snake in no time. This is very similar to a seat on a Mumbai local train, the moment an individual vacates a seat, it is promptly occupied by another opportunistic individual. The notion of translocation as a solution is unscientific and ineffective — a classic example of treating the symptom and not the systemic factors underlying and driving the process.

An interesting study, the King Cobra Telemetry Project, conducted in the wet evergreen rainforests of Agumbe, Karnataka, implanted king cobras with radio devices that relayed information about the snakes’ whereabouts. The researchers found that long-distance translocation could have deleterious effects on snakes, with their home ranges being much larger than “resident” snakes (i.e. those released in the same area post-capture and implantation of the radio tags), probably indicative of them searching for their prior home range or making exploratory movements, putting them at greater risk of predation or persecution by humans. Their findings are congruent with a similar study conducted on tiger snakes in suburban Melbourne, Australia and another study on white-lipped pit vipers in South China, where the results suggested that long-distance translocation is not the best practice for dealing with individual snakes in human habitation.

One of India’s first projects exclusively studying snakes in human habitation, particularly the Russell’s viper, is underway in Karnataka during 2020. Through this, we will obtain a better understanding of how snakes are using the landscape and navigating human-populated areas. “To understand snakes, we need to understand all the possible parameters that affect their movement, natural history, and behaviour. Human-snake conflict is a massive and urgent crisis and we need to understand the nature of the beast before we can hope for a solution”, says Gerry Martin, the herpetologist leading the project.

So far, we have ample circumstantial evidence from cities such as Mumbai, Dehradun, Bangalore, Tezpur, Guwahati, and so on, of these reptiles breeding within the concrete maze of cities. Juvenile snakes, eggs, shed snake skins, and the repeated observations of male-male combat of snakes have been seen in urban spaces and are all indicators of a resident, breeding population.

The most fascinating bit about urban snakes is that they are accustomed to a life around humans. There are several anecdotal experiences where these snakes have lived several years in an area, growing to massive lengths (some greater than seven feet!) without the humans that they share the space with even knowing of their existence. An interesting manner in which they do this is by extensively using the subterranean drainage system to navigate and feed.

I remember a particularly sharp five-foot-long rat snake that resided in a highly populated housing colony in Mumbai. It fed on toads all day long without ever being noticed by the residents walking three feet away from it as it moved between parked cars and along the edge of the boundary wall. If someone walked by, it would become still as a statue and suspend all action until the human had walked past. This often created a comical sight, such as when it froze midway through a meal with two toad legs sticking out of its mouth.

The way forward is to recognise that snakes are part of urban ecosystems, and that simply killing or removing them is not a viable solution. We need to focus conservation efforts to changing human perspectives of where snakes should be, and acknowledging the reasons for where they are there. We need to make people aware of the real solutions such as reducing the garbage that attracts rodents (following which the snakes will arrive).

Although rare in urban situations, snakebites have to be taken seriously. A nationwide study suggests that snakebites cause thousands of deaths across the country. In case a snake bites, the correct protocol has to be followed. So far, the only scientifically proven remedy for a venomous snakebite is the use of antivenom which can be administered by a medical professional. The antivenom is polyvalent, that is, it is effective against venom from the four species that are responsible for a majority of venomous snakebites in India, the saw-scaled viper, spectacled cobra, common krait and Russell’s viper. No traditional medicines have been medically proven to be of value, nor the chanting mantras, using a black stone to draw out venom, Ayurvedic herbs, sucking out the venom, and so on.

However, we must avoid getting bitten in the first place by taking simple precautions, such as keeping our surroundings clean, moving around with a torch at night, and not being aggressive towards any snake we see.

In our efforts at human-snake coexistence, we have found that pre-emptive, preventive, and participatory interventions work best in human-dominated areas. That is, engaging with people where snakes are known to reside before there is a call for a “rescue”, i.e. before a snake inadvertently enters a home or private area. This allows people to have interactive discussions without the tension and apprehension of dealing with a snake at that point of time. It simultaneously familiarises people with the presence of snakes around. Several of the locations where we have had such interactions have resulted in most people being okay with non-venomous snakes that inadvertently entered houses being released just outside; a paradigm shift from them wanting the snake to be released “as far away as possible”. These interventions draw from a successful human-leopard coexistence model that has been phenomenally successful in Mumbai, helping secure biodiversity conservation and social justice. “If we make people understand the nature of the species, that they avoid people, and assist the public through good safety directives, then people are quite open to using the best practices we have shared with them”, says Dr Vidya Athreya of the Mumbaikars for SGNP project.

The Maharashtra Forest Department has taken an extremely proactive step when dealing with human-snake coexistence, translating takeaways from wildlife science into on-ground practice and policy. Their protocol recommends first taking a call to see whether an intervention is necessary in the first place and if it is, then “release the snake as close to the rescue site as possible, and immediately”.

Given the lockdown imposed due to Covid-19 in 2020, a greater number of people are home, and these snakes that had previously not been noticed are being spotted more frequently. While snakes in the city may be cause for alarm for the urbanite, it is imperative to remember that the reason we are finding more and more of them around us is largely due to a detection bias and not a steep population increase. Snakes have always been around and will continue to thrive in the city.