Brown Tree Snake

Scientists tallying the economic damage wrought by invasive pests across the world found two species are responsible for more harm than any other.

The American bullfrog and brown tree snake have collectively caused $16.3bn in global damage since 1986. In addition to ecological harm, the invasive pair have ruined farm crops and triggered costly power outages.

The U.S. Department of the Interior's Office of Insular Affairs (OIA) has announced $4,095,922 million in Brown Tree Snake Control program fiscal year (FY) 2021 funding as administered through the Technical Assistance Program. An additional amount of $1,791,421 from Coral Reef and Natural Resources FY 2021 funds was also announced earlier this year for the purpose of controlling and mitigating other invasive species in the Insular Areas besides the brown tree snake. "Islands are particularly vulnerable to invasive species that disrupt natural, long-standing biological processes and threaten our unique, island eco-systems," said Deputy Assistant Secretary Keone Nakoa. "Each year, OIA provides significant funds to critical efforts seeking to help restore balance."

The Brown Tree Snake Control program FY 2021 funding was divided among several governments and federal partners to include Guam, the Commonwealth of the Northern Mariana Islands (CNMI), Hawai'i, U.S. Department of Agriculture (USDA), and the Department of the Interior. For more information about OIA funds provided to counter invasive species visit: https://www.doi.gov/oia/coral-reef-and-natural-resources-initiative.

On May 14, Director Reilly signed a Memorandum of Agreement with the Department of the Navy and the U.S. Fish and Wildlife Service. The MOA provides for continuity of operations for the USFWS and the USGS with construction of new office and lab facilities on the Guam National Wildlife Refuge in conjunction with DOD’s construction of a Marine Corps firing range. "The USGS has a long history of collaborating with the Department of Defense in support of U.S. facilities and force readiness in the INDOPACOM Area of Responsibility. One of our signature efforts ongoing today is a collaboration with DOD, the U.S. Fish and Wildlife Service, and the local government in minimizing the impacts of the invasive Brown Treesnakes (BTS) and improving BTS controls on military lands on Guam," said Jim Reilly, director of the USGS.

For the first time, an invasive brown treesnake population has been found on Cocos Island, an 83.1 acre atoll located 1.5 miles off the southwest coast of Guam. The brown treesnake was a major contributor to the loss of nine of 11 native forest birds and significant population declines of several native lizards, bats and other bird species on Guam. They now pose a threat to the wildlife of Cocos Island. Guam Department of Agriculture Division of Aquatic and Wildlife Resources is working with partners to better understand how many brown treesnakes are on the island and the best way to remove them.

Researchers from Dickinson College and the U.S. Geological Survey collaborated on field research to understand the ability of human searchers to detect the invasive brown treesnake (BTS) on the island of Guam. Due to their nocturnal and tree-dwelling habits, these snakes are extremely difficult to detect, especially when they are present at low densities in an area. A new study "Use of visual surveys and radiotelemetry reveals sources of detection bias for a cryptic snake at low densities" published in the journal Ecosphere, helps explain why and provides valuable information on optimizing search methods and search locations that could be valuable if the BTS was accidentally introduced to a snake-free island.

This report provides information on specific aspects of the Department’s BTS control program as required by Section 314 of Public Law 110-181. Submitted by The Office of the Secretary of Defense, Deputy Under Secretary of Defense (Installations and Environment).