Brown Tree Snakes in Guam: An Overview of the Problem and Strategies for Elimination
In the United States, hundreds of free-ranging snakes are discovered each year, most often due to escapes or releases from the pet trade. Most of them do not appear to have established a reproductive population. An animal can be harmful in an area not natively located.
The brown tree snake was introduced to the United States territory of Guam after World War II. Guam is a tiny U.S. territory located midway between Australia and Japan, and it's famous for having been occupied by the Japanese in World War II before being liberated by American troops in 1944.
Invasive brown tree snakes have been a major problem for Guam since they arrived on the island due to their ability to kill many birds and reptiles native only to Guam. They have devastated the indigenous birds, mammals, and lizards on the island, leaving only a few small species.
Brown tree snakes have also caused problems with rats by killing them off as well as other small mammals like mice or rabbits which can be harmful if their population gets out of control.
Brown Tree Snake's overview
A brown tree snake is a long, slender snake that can grow up to 12 feet in length. The body is a uniform brown or olive color with faint darker crossbands on the back. Juveniles are lighter colored and have more pronounced bands. The underparts are whitish and sometimes have black markings.
The brown tree snake is found in Indonesia, the Solomon Islands, New Guinea, and Australia. It is believed that brown tree snakes have been introduced accidentally by the U.S. military during World War II as they moved between islands in the South Pacific; there is no evidence that this species was ever on Guam before American colonization of the island (in fact, scientists now believe it may actually be native only to the island of New Guinea).
Brown tree snakes are nocturnal and spend most time balancing tree branches. They're great hikers, and they've even learned how to scale trees in the wild. They have a strong grip, excellent balance, and fast reactions. They can easily travel across vast open areas between trees in their native northern and eastern Australia, New Guinea, and Guam, where humans accidentally introduced them in the 1940s.
The brown tree snake is arboreal and nocturnal; they spend most of the day in trees, although it can also be found on or under rocks. They are excellent climbers and can hang from branches with just their tails.
The brown tree snakes multiplied rapidly and have virtually wiped out Guam's native forest birds.
The brown tree snake is an expert climber and spends most of its day in the trees where it resides. It preys on birds, their eggs, and small mammals like rats.
The brown tree snake has caused a lot of damage to the ecosystem in Guam. The snakes have killed many native birds and small mammals like lizards, birds, eggs, and rats.
Since the brown tree snake in Guam has no natural predators or other barriers on Guam, it has grown rapidly and nearly exterminated the island's native forest birds. Snakes also crawl on electrical lines, resulting in costly power outages and electrical damage.
Bites from brown tree snakes are rarely fatal, although extremely painful. Although these snakes may not be as poisonous as coral snake bites, their venom is still potent and causes a lot of discomfort.
They are not venomous, but many severe cases of ophiophobia (that's a snake phobia) were reported. Even though tree snakes are harmless to adults and no fatalities have been recorded but, young children can be frightened by tree snake bites.
Although the snakes are not considered dangerous to an adult human, and no deaths have been attributed to their bites, youngsters can experience symptoms from snake bite wounds.
Brown Tree Snakes in Guam Adopted the Lasso Climbing Technique
The brown tree snake has adapted to Guam's environment so well that it climbs electric poles by lassoing them with its tail, then scaling up using just its body strength, without ever relying on anything for assistance.
Brown Tree Snakes are great climbers and can often be found hanging onto a branch or even clutching onto a tree with their tails. But in Guam, brown tree snakes have adapted to climb power poles just by lassoing them with their tails and then scaling up using only body strength.
The brown tree snake has no natural predators and can live in a wide variety of habitats that include dense forests with high rainfall and coastal savannas with low humidity, and human-modified environments such as plantations and residential areas.
The brown tree snakes are so numerous that the damage they've caused to electrical systems alone equates to approximately $US4.5 million in the last seven years.
Researchers have discovered that brown tree snakes can climb this way, so they may develop improved defenses for the birds who live on Guam.
Researchers are trying to introduce modified nest box structures on electric poles protected by the smallest cone shape structure at the bottom and flares at the top. The plan is that if a snake attempts to lasso-climb the cone, it must loosen its grip as it goes up, causing it to fall.
Impact on ecosystem
Since the native fauna on Guam evolved without these scaly predators feeding on their eggs and youngsters, the jungle provided a feast for the invaders, allowing the population to skyrocket to more than two million snakes with densities of up to 5,000 individuals per square kilometer (or 13,000 per square mile).
Researcher Haldre Rogers from the University of Colorado says that the bird song that echoes on its neighboring islands has fallen strangely silent: "It's eerie on Guam – it's entirely silent."
According to fresh research published by Rogers and his team, the devastation of the island's birdlife has now had an impact on the tree population around it.
The researchers put huge baskets beneath two tree species in Guam and several neighboring islands to study how fruit-bearing trees distribute their seeds across the forest floor.
On Guam, fewer than 10% of the seeds dispersed from the parent tree made it beyond the immediate vicinity, whereas 60% of the seeds on snake-free islands did so.
"Apart from fruit bats, which are on the verge of extinction on Guam, nothing else can distribute seeds," Rogers added.
The decline of rodents, with more than two-thirds of the island's trees depending on them to distribute and germinate seeds, is expected to result in a devastating reduction in new forest growth of between 61 and 92 percent.
How to get rid of brown tree snakes?
There are several ways to get rid of the brown tree snake on Guam, but none have been proved successful in maintaining a constant watch on any new locations where they appear.
The ideal management technique is to prevent them from establishing themselves in new areas while also continuing to study tools such as improved traps, fumigants, toxicants, and attractants and control strategies such as parasites and viruses.
In recent years, U.S. Department of the Interior Assistant Secretary for Insular and International Affairs, Doug Domenech, announced $2.8 million to Combat Brown Tree Snake in Guam.
There are four stages of management when dealing with Brown tree snakes:
These are prevention, exclusion, reduction, and extermination. We will discuss each one below.
Prevention is a better way to deal with Brown tree snakes. This can be done by making sure that all cargo coming into Guam is inspected for the presence of snakes. In recent years, the U.S. department of agriculture has used pesticides to wage a chemical war on snakes in an $8 million campaign.
Exclusion involves creating barriers around an area so that the snakes cannot enter. This can be done by using fences, traps, or repellents. For example, using traps and repellents to reduce the number of snakes around an area (such as a farm or house) makes them less likely to be killed. This will help keep Guam free from Brown tree snakes without exterminating anyone on the island.
Reducing snake numbers can also involve creating habitat corridors that will help snakes move to other areas where they can find food and reproduce.
Extermination is the process of killing all the brown tree snakes in an area. If all else fails, this is the time to do it. As a last option, it should only be done if there are no other alternatives. The most common way to exterminate brown tree snakes is by using pesticides, which are expensive and dangerous.
Brown snakes are susceptible to paracetamol poisoning, a powerful painkiller that can harm many animals, including brown snakes.
By mixing paracetamol with other ingredients, it can be turned into a paste spread around the perimeter of an area.
Nida Riaz is a freelance blogger based in Pakistan. She started writing about her passion for the environment when the world came to a stop in early 2020.
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