Tree Snake

It’s sometimes called a cat snake because of its large eyes and vertical pupils.

The brown tree snake lives in the northern and eastern parts of Australia, in Papua New Guinea, the Solomon Islands as well as on the island of Guam. This snake is large in size sometimes growing to a length of 6.6 feet. It is venomous with fangs located in the back of its mouth. It eats bats, birds, rats, and lizards. It’s considered an invasive species in Guam.

Four Amazing Facts

• The longest one on record is 9.8 feet
• It lays four to 12 eggs in a crevice or beneath a rock to keep them cool
• This snake breeds year-round
• Though this snake’s venomous bite isn’t harmful to adults, it can be dangerous to children

Where to Find a Tree Snake

These snakes live in Australia, Papa New Guinea, the Solomon Islands, and Guam. They live up to their name by spending a lot of time hunting in trees. They also hunt for prey on the ground. Their habitat includes tropical forests, mangroves, caves, rocky areas, and grasslands. They sometimes show up in homes in suburban areas. These snakes are active at night and breed throughout the year.

Types of Tree Snakes

Tree snakes belong to the Colubridae family. There are 249 genera in this large family of snakes. Not surprisingly, the brown tree snake is not the only type of snake with a tree habitat.

One species of tree snakes native to tropical forests in South America is the blunt-headed tree snake (Imantodes cenchoa). Both this snake and the brown tree snake have large eyes with vertical pupils. However, the blunt-headed snake has a remarkably wide head whereas a brown tree snake’s head is large and elongated. There are 8 species of blunt-headed tree snakes listed below:

• Neotropical blunt-headed tree snake (Imantodes cenchoa)
• Chocoan blunt-headed vine snake (Imantodes chocoensis)
• Central American tree snake (Imantodes gemmistratus)
• Imantodes guane 
• Western tree snake (Imantodes inornatus)
• Amazon Basin tree snake (Imantodes lentiferus)
• Phantasma tree snake (Imantodes phantasm)
• Yucatán blunthead snake (Imantodes tenuissimus)

Brown tree snakes (Boiga irregulars) are native to Australia, Indonesia, and New Guinea. They also exist in Guam as an invasive species. Another category of tree snakes is the Australian tree snake (Dendrelaphis punctulatus). This reptile, also known as the green tree snake, lives in Australia like the brown tree snake. At 5.4 feet, the green tree snake is much smaller in size than the brown tree snake. Tree snakes in the genus Dendrelaphis, of which both the brown tree snake and Australian tree snake belong, include:

• Andaman bronzeback (Dendrelaphis andamanensis)
• Ashok’s bronzeback tree snake (Dendrelaphis ashoki)
• Boulenger’s bronzeback  (Dendrelaphis bifrenalis)
• Gore’s bronzeback (Dendrelaphis biloreatus)
• Binh’s bronzeback (Dendrelaphis binhi)
• Northern treesnake, green treesnake, coconut treesnake (Dendrelaphis calligaster)
• Striped bronzeback, grey bronzeback (Dendrelaphis caudolineatus)
• Gunther’s bronzeback tree snake (Dendrelaphis caudolineolatus) 
• Dendrelaphis chairecacos
• Blue bronzeback (Dendrelaphis cyanochloris)
• Sinharaja tree snake (Dendrelaphis effrenis) 
• Sulu bronzeback (Dendrelaphis flavescens) 
• Elegant bronzeback (Dendrelaphis formosus)
• Philippine lamp-black tree snake (Dendrelaphis fuliginosus)
• Montane treesnake (Dendrelaphis gastrostictus)
• Giri’s bronzeback (Dendrelaphis girii)
• Large-eyed bronzeback, southern bronzeback (Dendrelaphis grandoculis)^]
• Dendrelaphis grismeri
• Haas’s bronzeback (Dendrelaphis haasi)
• Dendrelaphis hollinrakei
• Nicobar bronzeback, Tiwari’s bronzeback (Dendrelaphis humayuni)
• Lesser Sunda bronzeback (Dendrelaphis inornatus) 
• Kei treesnake (Dendrelaphis keiensis)
• Kopstein’s bronzeback (Dendrelaphis kopsteini)
• Leviton’s bronzeback tree snake (Dendrelaphis levitoni)
• Dendrelaphis lineolatus
• Lorentz River treesnake (Dendrelaphis lorentzii)
• Luzon bronzeback treesnake (Dendrelaphis luzonensis) 
• Dendrelaphis macrops
• Maren’s bronzeback (Dendrelaphis marenae)
• Grey bronzeback, striped bronzeback (Dendrelaphis modestus)
• Nganson bronzeback (Dendrelaphis ngansonensis)  
• Sawtooth-necked bronzeback (Dendrelaphis nigroserratus)
• Oliver’s bronzeback (Dendrelaphis oliveri)
• Papuan treesnake (Dendrelaphis papuensis)
• Philippine bronzeback treesnake (Dendrelaphis philippinensis)
• Painted bronzeback, common bronzeback, Indonesian bronzeback (Dendrelaphis pictus)
• Dendrelaphis proarchos
• Common treesnake, Australian treesnake, green tree snake (Dendrelaphis punctulatus)
• Schokar’s bronzeback (Dendrelaphis schokari)
• Striped bronzeback, striated bronzeback treesnake (Dendrelaphis striatus) 
• Dendrelaphis striolatus

Paradise tree snakes (Chrysopelea paradisi) inhabit Southeast Asia and are commonly seen in palm trees. At a maximum of 3.9 feet, this snake is much smaller in size than the brown tree snake. A list of flying tree snakes in the Genus Chrysopelea are:

• Golden tree snake or ornate flying snake (Chrysopelea ornata)
• Twin-barred tree snake or banded flying snake (Chrysopelea pelias)
• Moluccan flying snake (Chrysopelea rhodopleuron)
• Sri Lankan flying snake (Chrysopelea taprobanica)
• Paradise tree snakes (Chrysopelea paradisi)

Scientific Name

The brown tree snake is called the Boiga irregularis. Another name for this reptile is the brown cat snake. It’s called a cat snake because of its notably large eyes with vertical pupils. It’s in the Colubridae family and class Reptilia.

Population and Conservation Status

The IUCN Red List of Threatened Species describes the population of these snakes as common and stable. It is reported as Least Concern.

Appearance and Description

The appearance of these snakes depends on what region they live in. Some have light brown scales covered with a dark brown or black pattern of bands. Others are cream or tan with reddish bands. This snake’s belly is tan or cream.

They have a narrow body measuring from 3.3 to 6.6 feet long. Their narrow body structure allows them to fit between rocks, branches, or even into a crevice.

This reptile is known as a cat snake because its vertical pupils are similar to a cat’s eyes. Another one of the interesting facts about brown tree snakes and cats is they are both nocturnal!

How to identify a brown tree snake:

• Light brown scales with a pattern of dark brown bands
• Tan or cream scales with a pattern of reddish bands
• A cream or tan belly
• Large eyes with vertical pupils
• A large head compared to its slender body

How Dangerous Are They?

These snakes are venomous, but the venom is considered mild. The fangs of this snake are in the back of its mouth and its venom is released slowly posing little danger to adults who are bitten. It’s more of a serious event if a child is bitten because of the person’s smaller size.

If an adult is bitten, it’s important to clean the wound with warm water and soap. Be sure to thoroughly dry the injured area before putting a clean bandage over it. If a child is bitten by this snake, try to keep the person calm and seek medical treatment right away. Fortunately, there’s an antivenom available to treat this snake’s bite.

Tree Snake Behavior and Humans

Because this is an arboreal snake, it usually goes unseen by people. It blends in well with the branches and leaves in its forest habitat.

They are not considered aggressive but can become agitated if they feel threatened.

These snakes are an invasive species in Guam. Shortly after World War II this snake was introduced to the island of Guam by accident. It started when one hid inside a crate in a cargo ship traveling to Guam. After arriving, the snake made its way onto the island. As time went along, their population grew. They fed on the large population of rodents and birds on Guam eventually causing the complete loss of some species. They quickly became pests on the island of Guam showing up in people’s homes in search of food.

Over the decades, Guam’s officials have taken steps to decrease the population of this invasive species of snake.

1. The State of Queensland Department of Environment and Science, Available here: https://environment.des.qld.gov.au/wildlife/animals/a-z/common-tree-snake
2. Conservation Made Simple, Available here: https://www.conservationmadesimple.org/blog/brown-tree-snakes-in-guam-an-overview-of-the-problem-and-strategies-for-elimination
3. Thai National Parks, Available here: https://www.thainationalparks.com/species/chrysopelea-paradisi
4. Wet Tropics, Available here: https://www.wettropics.gov.au/site/user-assets/docs/snakesofthewettropics.pdf
5. IUCN Red List, Available here: https://www.iucnredlist.org/species/116813025/1446031
6. Back Yard Buddies, Available here: https://backyardbuddies.org.au/backyard-buddies/green-tree-snake