As temperatures start to drop with the advent of winter, ectothermic animals start preparing for the change in season so as to adapt to the harsh and brutal cold. Ectothermic animals rely on the external environment to regulate their body temperature. Reptiles and amphibians are commonly known ectothermic animals who have to adjust to the changing environmental and weather conditions.
The word ectotherm comes from the Greek words ektós (meaning ‘outside’) and thermós (meaning ‘heat’). Ectothermic animals are not capable of thermoregulation. Thermoregulation is the ability to control one’s own body temperature to comply with the surrounding environment. One particular group of reptiles that cannot do this is snakes. Snakes have other adaptation strategies instead to survive colder temperatures.
In snakes, the internal physiological heat sources play a negligible role in regulating their body temperature, which makes these reptiles rely on the external environment for heat. They have evolved to undergo a process called ‘brumation’, which is usually thought to be their version of hibernation.
There is, however, a fundamental difference between these two processes. Hibernation is defined as complete inactivity, wherein an animal such as the Himalayan Brown bear goes to sleep and its heart rate drops to a significantly lower level. But in brumation, snakes are neither completely inactive nor do they go to sleep. It is a period of partial activity and their metabolism rates slow down tremendously.
The metabolism of snakes is generally lower than other animals, and that is why snakes can survive without a meal for up to a month. With snakes, their appetite starts reducing before the brumation period even starts and as a result, they require less energy to digest the food.
During the winter season, numerous snakes, sometimes more than a hundred live in one den. This nest is known as a hibernaculum and the mechanism assists in keeping themselves warm. Larger groups of individuals produce more energy and intertwined snakes facilitate maximum heat retention. The ideal hibernaculum also conceals the inhabitants from potential predators and permits breathing. Be it multiple species or many individuals of the same species staying together, this process is crucial to their survival.
It is possible that snakes may come out of their burrows during their brumation period to bask in the warmth of the winter sun, since that is the only source of external heat for these ectothermic animals. Since their metabolism rate slows down to a level where nourishment is not a critical issue, they are not likely to seek prey when they venture out during this time.
Terrestrial ectothermic species often have to brave sub-zero temperatures, winds and precipitation. For aquatic species, the waters solidify and limit the availability of oxygen. They are subject to starvation as well, as the species they depend on for prey often need to hibernate for the very same reasons. Some turtles, frogs and toads share a somewhat similar mechanism to brumation, to tolerate cold weather. They dig underneath leaf litter, logs, and even make burrows and dens. These animals also slow down their metabolism rate to conserve energy.
Some species are not as efficient when it comes to digging burrows or dens. Spring peepers (Hyla crucifer) and Wood frogs (Rana sylvatica) give way to the temperatures and literally freeze! Their breathing ceases, as does their heartbeat, and they appear dead to the naked eye, except they aren’t! You may ask, “how do they survive such an ordeal?”
A high concentration of glucose in their internal organs serves as an anti-freezing agent, and provides these amphibians nourishment as well during this process. As the season changes and the sun’s warm rays work their magic, they literally ‘spring’ back to life in spring. Their bodies thaw and they begin feeding and mating again. While freezing and thawing of the body can be lethal, it is managed by combining an array of molecular and physiological responses that can avoid the loss of cells and tissues. If this is not cryopreservation as shown in sci-fi movies (remember Avatar and Interstellar?), we do not know what is!
In Jammu and Kashmir, Wildlife SOS operates a rescue team out of Srinagar where the temperature has currently dropped to as low as 1o C, and the weather has become challenging for snakes. With the arrival of winter, snake sightings begin to lessen. This is evident from the number of interface or rescue calls that our team receives. During summers, we often receive up to 4 calls in a single day, but during the winter season, they reduce drastically. The Wildlife SOS Rapid Response Unit in Jammu & Kashmir rescued over 80 snakes in the summer of 2022 as compared to none in last year’s winter.
Similarly, in two more cities where Wildlife SOS actively carries out animal rescues, there is a visible drop in reptile appearances. In northern India, the NGO’s rescue teams in Agra and Delhi-NCR rescued 53 and 54 reptiles respectively last winter, as compared to 78 reptiles in Delhi-NCR and 144 reptiles in Agra in the summer of 2022. These numbers indicate how less active our reptilian denizens actually are during the colder months of the year.
While the numbers are lower, they certainly suggest that snakes may appear during winter, bringing people in confrontation with the reptiles. Wildlife SOS runs 24×7 emergency rescue helplines across four regions in the country, namely Delhi-NCR (+91 9871963535), Agra (+91 9917109666), Vadodara (+91 9825011117), and Jammu & Kashmir (+91 7006692300, +91 9419778280). In such cases, we encourage people to not do anything by themselves and always dial the Wildlife SOS emergency helpline so that the experts can tactfully handle these situations.