A USGS scientist holds an invasive brown treesnake.
What is the brown treesnake?
The Brown Treesnake is native to parts of Indonesia, the Solomon Islands, New Guinea, and Australia. The snake was first sighted on the island of Guam in the 1950s, probably after stowing away on cargo ships coming from New Guinea. In 2020, a population of Brown Treesnakes was discovered on Cocos Island, a small atoll of the southern shore of Guam, which represents the first instance of Brown Treesnakes establishing off the island of Guam.
The snakes feed on lizards, birds, small mammals, and eggs. Since the treesnake has no natural predators or other controls on Guam, it multiplied rapidly and has devastated Guam’s native forest birds. The snakes also crawl on electrical lines and cause expensive power outages and electrical damage.
Brown Treesnakes are mildly venomous. While the snakes are not considered dangerous to an adult human and no known deaths have occurred, young children can have reactions to treesnake bites.
Many techniques have been discussed to eliminate the Brown Treesnake in Guam, but there is no known way to remove them entirely. The best management strategy is to keep them from becoming established at new locations while continuing to do research on tools such as improved traps, fumigants, toxicants, and attractants; and on control options such as parasites and viruses.
Learn more: Brown Treesnake Research on Guam
Related
How is the USGS helping to prevent the spread of the brown treesnake?
Preventing the spread of the invasive brown treesnake (Boiga irregularis) is paramount. Without rigorous prevention, control (let alone removal) of an introduced reptile species is extremely difficult. In the case of the brown treesnake, prevention efforts include working to detect stowaway snakes before they leave the island, as well as extreme vigilance on islands where the snakes are most...
What is an invasive species and why are they a problem?
An invasive species is an introduced, nonnative organism (disease, parasite, plant, or animal) that begins to spread or expand its range from the site of its original introduction and that has the potential to cause harm to the environment, the economy, or to human health. A few well-known examples include the unintentional introduction of the West Nile virus, chestnut blight, the South American...
Are invasive snakes dangerous?
Free-ranging snakes representing dozens of species from around the world are discovered in the United States in any given year, usually as a result of escapees or releases from the pet trade, but most of these don't appear to have established a reproductive population. Any animal can be problematic when released in places where it is not native. For example, the Brown Treesnake was introduced to...
Are there invasive reptiles other than Burmese pythons in the United States that people should be concerned about?
Free-ranging, non-native reptiles representing dozens of species from around the world escape or are illegally released in the United States every year. Many of these species fail to establish reproductive populations, but some are successful. Florida is a major transportation hub and has a climate that is suitable for many invasive species across taxonomic groups. Due to the suitable climate, and...
Are large constrictor snakes such as Burmese pythons able to kill people? What is the risk? Would this be in the wild, or in backyards?
Human fatalities from non-venomous snakes are very rare, probably averaging one or two per year worldwide. All known constrictor-snake fatalities in the United States are from captive snakes; these are split between deaths of snake owners who were purposefully interacting with their pet and deaths of small children or infants in homes where a snake was kept captive as a pet. There have been no...
Can invasive pythons be eradicated?
The odds of eradicating an introduced population of reptiles once it has spread across a large area is very low – pointing to the importance of prevention, early detection, and rapid response. With the Burmese python now distributed across more than a thousand square miles of southern Florida, including all of Everglades National Park and across the southern coast to Rookery Bay National Estuarine...
How have invasive pythons impacted Florida ecosystems?
Non-native Burmese pythons have established a breeding population in South Florida and are one of the most concerning invasive species in the area. Pythons compete with native wildlife for food, which includes mammals, birds, and other reptiles. Severe declines in mammal populations throughout Everglades National Park have been linked to Burmese pythons, with the most severe declines in native...
Scientist holding brown treesnake
A USGS scientist holds an invasive brown treesnake.
A brown treesnake on frangipangi blossoms
A brown treesnake crawls on some frangipangi blossoms in Guam.
A brown treesnake crawls on some frangipangi blossoms in Guam.
Invasive brown treesnake
Brown treesnakes were a major contributor to the loss of nine of 11 native forest birds on Guam.
Brown treesnakes were a major contributor to the loss of nine of 11 native forest birds on Guam.
A brown treesnake in a Streptopelia bitorquata nest
A brown treesnake in a Streptopelia bitorquata (island collared dove) nest. Yona, Guam, 2009. Photo by James Stanford, USGS.
A brown treesnake in a Streptopelia bitorquata (island collared dove) nest. Yona, Guam, 2009. Photo by James Stanford, USGS.
A brown treesnake in a tree in Guam.
A brown treesnake in a tree in Guam. Photo by Bob Reed, USGS, 2009.
A brown treesnake in a tree in Guam. Photo by Bob Reed, USGS, 2009.
Related
How is the USGS helping to prevent the spread of the brown treesnake?
Preventing the spread of the invasive brown treesnake (Boiga irregularis) is paramount. Without rigorous prevention, control (let alone removal) of an introduced reptile species is extremely difficult. In the case of the brown treesnake, prevention efforts include working to detect stowaway snakes before they leave the island, as well as extreme vigilance on islands where the snakes are most...
What is an invasive species and why are they a problem?
An invasive species is an introduced, nonnative organism (disease, parasite, plant, or animal) that begins to spread or expand its range from the site of its original introduction and that has the potential to cause harm to the environment, the economy, or to human health. A few well-known examples include the unintentional introduction of the West Nile virus, chestnut blight, the South American...
Are invasive snakes dangerous?
Free-ranging snakes representing dozens of species from around the world are discovered in the United States in any given year, usually as a result of escapees or releases from the pet trade, but most of these don't appear to have established a reproductive population. Any animal can be problematic when released in places where it is not native. For example, the Brown Treesnake was introduced to...
Are there invasive reptiles other than Burmese pythons in the United States that people should be concerned about?
Free-ranging, non-native reptiles representing dozens of species from around the world escape or are illegally released in the United States every year. Many of these species fail to establish reproductive populations, but some are successful. Florida is a major transportation hub and has a climate that is suitable for many invasive species across taxonomic groups. Due to the suitable climate, and...
Are large constrictor snakes such as Burmese pythons able to kill people? What is the risk? Would this be in the wild, or in backyards?
Human fatalities from non-venomous snakes are very rare, probably averaging one or two per year worldwide. All known constrictor-snake fatalities in the United States are from captive snakes; these are split between deaths of snake owners who were purposefully interacting with their pet and deaths of small children or infants in homes where a snake was kept captive as a pet. There have been no...
Can invasive pythons be eradicated?
The odds of eradicating an introduced population of reptiles once it has spread across a large area is very low – pointing to the importance of prevention, early detection, and rapid response. With the Burmese python now distributed across more than a thousand square miles of southern Florida, including all of Everglades National Park and across the southern coast to Rookery Bay National Estuarine...
How have invasive pythons impacted Florida ecosystems?
Non-native Burmese pythons have established a breeding population in South Florida and are one of the most concerning invasive species in the area. Pythons compete with native wildlife for food, which includes mammals, birds, and other reptiles. Severe declines in mammal populations throughout Everglades National Park have been linked to Burmese pythons, with the most severe declines in native...
Scientist holding brown treesnake
A USGS scientist holds an invasive brown treesnake.
A USGS scientist holds an invasive brown treesnake.
A brown treesnake on frangipangi blossoms
A brown treesnake crawls on some frangipangi blossoms in Guam.
A brown treesnake crawls on some frangipangi blossoms in Guam.
Invasive brown treesnake
Brown treesnakes were a major contributor to the loss of nine of 11 native forest birds on Guam.
Brown treesnakes were a major contributor to the loss of nine of 11 native forest birds on Guam.
A brown treesnake in a Streptopelia bitorquata nest
A brown treesnake in a Streptopelia bitorquata (island collared dove) nest. Yona, Guam, 2009. Photo by James Stanford, USGS.
A brown treesnake in a Streptopelia bitorquata (island collared dove) nest. Yona, Guam, 2009. Photo by James Stanford, USGS.
A brown treesnake in a tree in Guam.
A brown treesnake in a tree in Guam. Photo by Bob Reed, USGS, 2009.
A brown treesnake in a tree in Guam. Photo by Bob Reed, USGS, 2009.
Updated Date: March 18, 2024