By David Kaunyangi
The Snake Islands-Brazil
Snakes have a negative reputation that is usually unwarranted. There are some deadly snakes to be cautious of, but for the most part, snakes are harmless, and none of them want to interact with humans. When you approach them, whether on purpose or by mistake, the first thing they'll try to do is crawl away. Without snakes, we'd probably have a lot more rodents in our homes than we do now. They play a vital role in our ecology.
There is one place where even those not frightened by snakes would likely be terrified. This place is called Snake Island. Its official name is Ilha da Queimada Grande, and it is located about 90 miles off the coast of Brazil. It is beautiful with a mix of rainforest and rocky slopes. This 106-acre tiny island would be a wonderful place to have a picnic — if it wasn't for the up to 4,000 lancehead vipers that are permanent residents of this deserted island.
How The Island did came into Existence.
This was not an island thousands of years ago. It was connected to the mainland of Brazil. The animals were free to roam the area as they wanted. There were snakes and various other animals in what would be called an average population. Jararaca snakes were one of the snake populations during the time.
As the previous Ice Age ended and sea levels increased, a period of steady warming began around 11,000 years ago. This land had some higher elevation sections and was 90 miles from the mainland when the sea level rose. Except for birds, everything on the island is now trapped. The jararaca snakes were among them. There was nothing on the lonely island that ate the snake, but there was plenty of food for the snake. The number of snakes has exploded.
It finally reached its carrying capacity or the maximum population sustained in a specific area. There were far too many snakes, and the situation could no longer be sustained. There were almost no more rodents for the snakes to consume on the island.
The number of jararaca snakes declined, but natural selection took over. Some snakes acquired mutations that aided them in a variety of ways. Initially, some of the snakes excelled at catching birds. Birds may still come and go on this island, preventing them from becoming extinct like rodents. Still, there remained an issue. Most venomous snakes bite their target and then stalk them until the venom takes effect. That doesn't work with birds because they can flee before the venom takes effect. Another mutation increased the venom's potency significantly.
Additionally, instead of letting go of the birds, the snakes learned to hold on to them for a short time. This is how lancehead vipers developed into their species and became one of the world's deadliest snakes. A bite can kill a human in less than an hour. Their capacity to primarily hunt birds, combined with a lack of predators, resulted in a population that was quite dense when compared to snake populations elsewhere on the planet.
According to some estimation, there is one viper for every square meter of land on the island. That implies you wouldn't be able to walk more than a few paces without coming across this dangerous snake. For most folks, it's a nightmare! A lighthouse used to be operated by a few humans on the island, but that ceased in the 1920s when the lighthouse was automated. Snake Island now has just a few select scientists who have a permit to research the snakes and a once-a-year visit by the Brazilian Navy to check on the lighthouse. They must bring a doctor along with them.
No other visitors are allowed on the island, and most inhabitants are satisfied. Of course, some people sneak over to collect snakes and sell them to snake enthusiasts illegally. A single lancehead viper can fetch up to $25,000 on the black market. As a result of either accidental or deliberate release, some of these species now dwell on the mainland. In Brazil, it is presently the most prevalent type of snake bite. Snake Island is a remarkable example of natural selection due to geographic isolation.
Resources
The mysteries of SNAKE ISLAND – The Kansan. https://www.thekansan.com/2022/01/20/the-mysteries-of-snake-island/
Sherwood Birthing Unit - Sherwood Forest Hospitals. https://www.sfh-tr.nhs.uk/our-services/maternity/sherwood-birthing-unit
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