The Brown Tree Snake

A deadly invasion.

Background


  • Common name: Brown Tree Snake


  • Scientific name: Boiga irregularis


  • Native range: South Pacific; Solomon Islands, New Guinea, and Northern Australia


  • Appearance: colors on its back range from yellow to brown and its bottom ranges from a yellow to cream color; its head has a greater width than its body; vertical pupils; averages 18 inches when born and can grow up to 9 feet long, though they usually are about 3-6 feet long


  • Niche: tropical species of snake that usually live in trees and shrubs, though they can be found on the ground and on grasslands; diet includes birds, bird eggs, lizards, lizard eggs, bats, rats, and small rodents; females usually produce 4-12 eggs in a given season; usually mate twice a year; nocturnal; mildly venomous

The Brown Tree Snake's natural habitat

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What the Brown Tree Snake's normal food chain would look like

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How the Brown Tree Snake has effected the food web in Guam

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The Invasion

Reason Why & Its Impact

Since World War II, when the Brown Tree Snake was first introduced to Guam and Hawaii through cargo ships, it has eradicated 9 out of 13 bird species, and 3 lizard species.

Unlike its natural habitat, it has no natural predators in this area so it has flourished at the cost of other species. It is also not controlled by disease or competition, which are its usual limiting factors. On top of all this, the snake has now moved on to eating other lizards and skinks, which support the growing population of snakes due to their ability to reproduce at a very high rate. Because of this the environments carrying capacity has increased dramatically for the snakes. All these factors put together add up to the snakes increasing population size that is threatening, not only the lives of many other animals, but also the lives of humans.

Since the snake's introduction in Guam, the number of power outages has increased because the snakes have been climbing on the power lines and messing with electrical boxes. This is causing serious problems for the country's economy because they are having to pay for the damages. Also, because the snakes have eaten away the bird and lizard populations, the insect populations have increased, causing trouble for farmers and their crops.

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How Things Have Changed

This particular species of snake has impacted many areas, Guam especially. Since the snake was first introduce its numbers have increased from none at all to 30-50 per 100 acres of land. Although the numbers of the population have been dropping since it has over-exceeded the environment's carrying capacity.

Future Prognosis

Due to the environment's carrying capacity, the brown tree snake cannot spread much further than it already has in Guam, though the same cannot be said for Hawaii which is struggling to keep the number of snakes at bay.

Many precautions have been made to keep the snakes out of the state. One thing the islanders are doing now is using dogs to sniff out the creatures on ship and airplane cargo to make sure none escape into the island's forests. Another method that studies are pointing to is the poisoning of the animal in order to reduce it's population size. These methods have been working so far, and the island's council hopes it will continue to do so.

How You Can Help

There aren't many things humans can do to stop the invasive spread of the snake. One of the only things someone can do is to report any sightings of a brown tree snake to government officials or the local animal control agency.

Poll Questions