Secrets of Polish Constrictor Snakes

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He tracks snakes. He sticks transmitters to their scales, and he knows what nooks and crannies they slip into. He accompanies them in marshy thickets and in their big-city hideouts. He knows the secrets of creatures that others fear. Even if accidentally bitten by his own fault, he argues that a viper will never attack someone without reason. After all, it is thanks to snakes that we have a valuable elixir: venom used in medicines for hypertension and blood clotting. Oh yes, the Sorting Hat would have no doubts about him: “Stanisław Bury, Slytherin!” In real life, the winner of the FNP START program from the Institute of Environmental Sciences at the Jagiellonian University in Krakow.

A snake basking in the sunlight on a stone cannot be dangerous. When it feels a human approaching, it will immediately try to escape. It is lying motionless beside a mountain path because it must extract heat from the environment in order to gain the energy it needs to live. This is done by all ectotherms, or cold-blooded creatures. Most snakes cannot shiver and warm themselves this way, like humans and endothermic animals.

Instead of reacting with fear or aggression, we should learn more about Polish snakes, preferably from a scientist. The secrets of snakes are known to researchers thanks to sensors stuck to scales of these reptiles. Dr. Stanisław Bury also knows a lot about the problems these protected and increasingly rare animals face.

Not chill but hunger

Snakes generally do not tolerate urban expansion. However, city areas constantly grow and may even double in the next 20 years. Bury’s research shows that in Krakow, grass snake reaches a smaller body size compared to snakes from natural or slightly modified areas. We may associate this change with their higher risk of death on the road, among other places. Snakes are simply less likely to live to an age when they reach their full body size. Moreover, food availability may be limited in urban environment. The staple food of grass snakes are amphibians, which are now in decline.

Common sense suggests that climate warming should place snakes in a better position than previously. However, the matter is not that simple. At high temperatures, reptilian metabolism accelerates. On the one hand, it enables faster reactions to changes in the external environment but, on the other hand, it also means a higher food requirement. As the climate warms up, the winter season shortens, and the time with higher temperatures lasts longer. Therefore, snakes expense and need more energy. Meanwhile, they have nowhere to find its source because food is scarce in the environment.

Scientists confirm that biodiversity is declining, and populations of many species eaten by snakes diminish as well. The snakes can also fall prey to predators more often, since the latter’s annual activity has increased. So, snakes now face a double risk of being eaten and not finding food.

Stanisław_Bury_Archiwum prywatne
Dr Stanisław Bury / private archive

 

Why study snakes?

There are four species of snakes in Poland, with a fifth species sometimes joining the list: the dice snake. The rarest is the Aesculapian snake, which mainly inhabits the Bieszczady Mountains. It hunts like a constrictor, which means that it wraps its prey in the tangles of the body. The Aesculapian snake feeds on small rodents and birds, which it swallows whole, just like other snakes do. Such a foraging method may make many people reluctant to snakes. But the way other animals get food is also not very pleasant. For example, a jaguar bites through its victim’s skull, spiders inject venom that eats the victim from the inside, vampire bats cut skin with their teeth and drink the blood of other mammals, while other predators simply bite they catch to death.

“The Aesculapian snake indeed chokes and immobilizes its victims to kill them. However, the way humans obtain food of animal origin is even more unpleasant. I recommend looking at these issues from a broader perspective. How animals function in the wild results from long evolutionary processes and has an ecological context. Each animal is part of the food chain in the ecosystem and has to eat somehow,” explains Stanisław Bury.

Another rare Polish species is the smooth snake. Grey-brown, spotted, up to 80 centimeters long. Sometimes confused with the common European viper, the smooth snake is nevertheless completely harmless. The next two species are relatively numerous: grass snake and common European viper are present almost all over Poland. However, the viper is most numerous in the mountains. Measuring 70–80 centimeters in length, the common European viper is the only poisonous snake in Poland. A viper bite can be a health hazard, but Bury assures that it is very rarely fatal. This snake is equipped with a venom designed to damage tissues. But the common European viper has the venom to hunt small vertebrates like rodents, lizards, and amphibians, several hundred times smaller than a human.

Stanisław Bury admits that he was bitten by a viper but takes the blame for the incident. He estimates that he was not careful during fieldwork. In the following years, he dealt with dozens of vipers, and he had never seen any of them aggressive. Bury warns that you should not approach the viper, try to catch it, or attack it in any way. If you are bitten, you must go to the emergency room.

Humans’ Poisonous Allies

Researchers are checking how snakes react to climate change, which is the biggest problem of the entire biosphere. On this basis, they conclude how further climate change disturbs the functioning of protected species, and they try to develop remedies.

“No organisms can function independently, including those we use. The protection of the entire ecosystem is essential. Snakes function as very good population control of organisms we consider pests, for instance, rodents that feed on crops. The biomass of rodents eaten or hunted down by snakes can be significant,” says Bury. “Besides, snake venom is used in the production of various drugs related to hypertension and blood clotting.”

To understand the habits and problems of snakes in the natural environment, scientists use radio telemetry. They stick transmitters on captured individuals. Although the snake can lose it by shedding its epidermis or rubbing against the brush, it remains a relatively non-invasive way to accurately track the movement of snakes. Researchers catch the signal from the antenna and can locate the snakes even hidden in dense vegetation. Poles conducted such studies, among others, on Aesculapian snake and smooth snake by the NATRIX Herpetology Society.

“A snake hidden in a hideout, for example among stones, is incredibly hard to find. This method allows us to deal with the secretiveness of these animals. We can assess how they move, what habitats they use at different times of day and year. On this basis, we can actually protect these habitats and adopt active protection measures to the needs of animals,” explains Stanisław Bury.

Armed with the results of such studies, naturalists can select and create places where the snake can shelter and reproduce. It is important because the breeding habitats of the Aesculapian snake began to disappear. Paradoxically, these snakes are strongly related to the presence of humans because they love composters or manure, in which they can lay eggs. Aesculapian snake grows up to even 170 centimeters in length, it has spots in youth and becomes brown with maturation.

Friendship from Childhood

Stanisław Bury familiarizes primary school children with snakes. He is of the opinion that adults’ fear and disgust with snakes are learned reactions. What is natural is curiosity.

“I show the children a live corn snake. It is a gentle species often found on farms. The children simply bolt to see this snake up close, pick it up, see it, and touch it. Their impressions are positive; snakes do not have slimy skin and are not aggressive. On the contrary, they are incredibly skittish animals. Tourists usually do not notice snakes because they simply run away. They do not attack by themselves,” says Bury.

Sometimes, we find snakes in the water, especially grass snakes. Grass snakes like to swim, they do it very well, and they prefer to hunt for fish or amphibians. Adult grass snakes can reach large sizes, even over one meter in length. Nevertheless, they are completely harmless to people and should simply be left alone if you encounter them.

The same goes for a viper on a mountain trail. It is best to leave or wait because the viper will run away on its own. If it is still slow, because it has not warmed up enough in the sun, it will be unable to escape. You must let it continue basking in the sun, pass it by, and go your way.

Stanisław Bury prefers to take breaks from the multitude of scientific activities in the mountains, away from the city, in open spaces.

Karolina Duszczyk

At the top of the page: Dr. Stanisław Bury; photograph by Radosław Niziołek.