Scientists with the USGS Brown Treesnake project conduct research on this snake species, including control tool development and validation, ecology and ecological impacts, and early detection methods. The program has been expanded to include other invasive reptiles, such as the Burmese Python, Boa Constrictor, and Northern African Python in Florida and invasive watersnakes in California.
Brown Treesnake Research
Biology, Impacts and Control of Invasive Reptiles in the Everglades
Biology, Impacts and Control of Invasive Reptiles in the Pacific
Fort Collins Science Center Labs and Facilities
USGS Brown Treesnake Laboratory - Guam
Documenting, Mapping, and Predicting Invasive Species Using the Fort Collins Science Center's RAM (Resource for Advanced Modeling)
Developing and Testing Methods for Extracting Environmental DNA from Soil Samples, with Applications to Detection of Brown Treesnakes
Brown Treesnake Rapid Response Team
Control and Landscape-Scale Suppression of the Invasive Brown Treesnake
Recent data (2020-2022) related to USGS brown treesnake research are listed below. A complete listing of USGS brown treesnake data is available from the button below.
Brown treesnake capture and morphometric data using live mouse- and bird-lure traps on Guam, 2013
Camera trap data of Brown Treesnakes at mouse-lure traps on Guam, 2015
Brown Treesnake morphological and behavioral differences following ingestion of large meals, 2015
Surveillance and reports of Brown Treesnakes on Saipan, 1980-2020
Brown Treesnake trap captures, Guam National Wildlife Refuge, 2014
Offspring, dam, sire pedigree assignments in a managed population of Brown Treesnakes on Guam
Brown Treesnake detections on transects using potential attractants of live-mouse lures or fish-spray scent, Guam
Exogenous and endogenous factors influence invasive reptile movement at multiple scales, 2018 - 2019
Demographic data for toxicant based trial eradication of brown treesnakes in the USGS Closed Population on Guam, 2016 - 2020
Brown Treesnake mating and reproductive success on Guam, 2004-2018
Monitoring mortality of brown treesnakes fed an oral toxicant (acetaminophen) in an external bait placement dosing technique in the laboratory, 2017
Visual Surveys and Morphometrics of Brown Treesnakes in Mariana Swiftlets caves on Guam
Recent publications (2020-2022) related to USGS brown treesnake research are listed below. A complete listing of USGS brown treesnake publications is available from the button below.
Individual heterogeneity influences the effects of translocation on urban dispersal of an invasive reptile
Can we prove that an undetected species is absent? Evaluating whether brown treesnakes are established on the island of Saipan using surveillance and expert opinion
Demographic response of brown treesnakes to extended population suppression
Olfactory lures in predator control do not increase predation risk to birds in areas of conservation concern
Female persistence during toxicant treatment predicts survival probability of offspring in invasive brown treesnakes (Boiga irregularis)
Foraging behavior in a generalist snake (brown treesnake, Boiga irregularis) with implications for avian reintroduction and recovery
Brown treesnake mortality after aerial application of toxic baits
Distilling professional opinion to gauge vulnerability of Guam avifauna to Brown Treesnake predation
Trait heritability and its implications for the management of an invasive vertebrate
Surface material and snout-vent length predict vertical scaling ability in brown treesnakes:an evaluation of multispecies barriers for invasive species control on Guam
Locally abundant, endangered Mariana swiftlets impact the abundance, behavior, and body condition of an invasive predator
Recent recovery and expansion of Guam’s locally endangered Såli (Micronesian Starling) Aplonis opaca population in the presence of the invasive brown treesnake
- Overview
Scientists with the USGS Brown Treesnake project conduct research on this snake species, including control tool development and validation, ecology and ecological impacts, and early detection methods. The program has been expanded to include other invasive reptiles, such as the Burmese Python, Boa Constrictor, and Northern African Python in Florida and invasive watersnakes in California.
Brown Treesnake ResearchBiology, Impacts and Control of Invasive Reptiles in the Everglades
Invasive species are considered to be second only to habitat degradation in terms of negative impacts on the Earth’s ecosystems, and our scientists make up a significant proportion of the global expertise in the rapidly-growing problem of invasive reptiles.Biology, Impacts and Control of Invasive Reptiles in the Pacific
Research on Guam has led to development and validation of numerous effective control tools, including the advancement of reptile control to support native species recovery.Fort Collins Science Center Labs and Facilities
The Fort Collins Science Center has scientists working in several diverse locations as well as three in house highly specialized laboratories, studying subjects from molecular ecology to brown treesnakes, dendroecology to streamflows, and macroinvertebrate species to Burmese pythons. Our extraordinary scientists work in each of these locations advancing studies in their particluar areas of study...USGS Brown Treesnake Laboratory - Guam
USGS scientists and staff associated with the Brown Treesnake Project are co-located at the Guam National Wildlife Refuge at the northern end of Guam in the western Pacific Ocean. Project staff work on developing and testing control tools for invasive brown treesnakes, as well as understanding their impacts on Guam's ecosystems. Project staff also lead the multi-agency Brown Treesnake Rapid...Documenting, Mapping, and Predicting Invasive Species Using the Fort Collins Science Center's RAM (Resource for Advanced Modeling)
The Resource for Advanced Modeling room provides a collaborative working environment for up to 20 scientists, supported with networked, wireless computing capability for running and testing various scientific models (e.g., Maxent, Boosted Regression Trees, Logistic Regression, MARS, Random Forest) at a variety of spatial scales, from county to global levels. Models use various predictor layers...Developing and Testing Methods for Extracting Environmental DNA from Soil Samples, with Applications to Detection of Brown Treesnakes
Environmental DNA (eDNA) is organismal DNA that can be found in the environment. Environmental DNA originates from cellular material shed by organisms (via skin, excrement, etc.) into aquatic or terrestrial environments that can be sampled and monitored using new molecular methods. Such methodology is important for the early detection of invasive species as well as the detection of rare and...Brown Treesnake Rapid Response Team
Brown Treesnakes continue to cause major problems for the ecology, economy, and quality of life on Guam. Our scientists conduct research on this snake species, including control tool development and testing, ecological impacts, and early detection methods. We hold Brown Treesnake Rapid Response Team training courses on Guam throughout the year to develop the skills needed to effectively respond to...Control and Landscape-Scale Suppression of the Invasive Brown Treesnake
The Brown Treesnake is a highly destructive reptile species that has extirpated many native species of birds, bats, and lizards from the U.S. Territory of Guam. For more than two decades branch scientists with the Invasive Reptile Project have developed, validated, and tested the feasibility of Brown Treesnake control and suppression at various spatial scales. - Data
Recent data (2020-2022) related to USGS brown treesnake research are listed below. A complete listing of USGS brown treesnake data is available from the button below.
Filter Total Items: 20Brown treesnake capture and morphometric data using live mouse- and bird-lure traps on Guam, 2013
We deployed 30 trap stations consisting of three combinations: isolated bird-lure traps, isolated mouse-lure traps, or paired stations to evaluate snake capture as a function of lure. At the paired stations, we included two traps: one bird-lure trap and one mouse-lure trap. All stations were at least 60 meters (m) apart and each of the station treatments was replicated 10 times. Traps at paired stCamera trap data of Brown Treesnakes at mouse-lure traps on Guam, 2015
Manually photo-processed remote camera trap data of Brown Treesnakes on Guam at snake traps with live mouse lures. Records of snakes entering the field of view (FOV) and exiting the FOV by day, time, and trap location. Photos were further processed to retain only detections of snakes up to 1.83 meters from the camera, i.e., only records of snakes that were on or in front of the mouse-lure trap areBrown Treesnake morphological and behavioral differences following ingestion of large meals, 2015
Data set resulting from monitoring the behavior of snakes (n = 62) that had been feed a standardized large meal with transmitter, proportional to their body mass, to make direct comparisons to a control group of snakes that had not been fed a meal (only the transmitter). Transmitters were equipped with a two-position switch that changes pulse rate when the body position of the animal changes moreSurveillance and reports of Brown Treesnakes on Saipan, 1980-2020
Available active surveillance efforts for Brown Treesnakes on the island of Saipan via nocturnal visual encounter surveys and trapping from 1999-2018 were collected and summarized into 3 csv files (TRAP1999, BTSRRTSaipanTRAP, and BTSRRTSaipanVISUAL). Location and date of non-confirmed reports of snakes 1982-2013 via passive surveillance were compiled into a fourth file (Saipan BTSSightings1980_202Brown Treesnake trap captures, Guam National Wildlife Refuge, 2014
Over a 22-week period both with and without active Brown Treesnake (BTS) snake removal, we evaluated snake-trap contact rates at mouse- and bird-lure traps within the Guam National Wildlife Refuge in 2014. Bird-lure traps served as a proxy for reintroduced nesting birds. Data consists of 3 files generated from camera surveillance and trapping using mouse and bird lures in conventional snake trapsOffspring, dam, sire pedigree assignments in a managed population of Brown Treesnakes on Guam
In this dataset offspring are assigned to a dam and sire using information from single nucleotide polymorphisms (SNPs) from previously published pedigree reassignments of Brown Treesnakes within the U.S. Geological Survey's Brown Treesnake study enclosure on Northwest Field of Andersen Air Force Base, Guam (Levine and Yackel Adams 2021 and Nafus 2021) to update the overall pedigree dataset for snaBrown Treesnake detections on transects using potential attractants of live-mouse lures or fish-spray scent, Guam
Nocturnal visual encounter surveys for Brown Treesnakes were collected and summarized into 4 plain text files (csv format): CapturesLure, SurveysLure, CapturesScent, and SurveysScent. Capture files contain unique Passive Integrated Transponder (PIT) tag identification and measurements of snakes with dates and locations of capture. Survey files contain the dates of transect sampling and treatment aExogenous and endogenous factors influence invasive reptile movement at multiple scales, 2018 - 2019
These data reflect movement values for brown treesnakes from Guam that were translocated (moved by humans) to new locations or were resident (left in place) on Guam. The data are related to the specimen's treatment group, individual values, locations and other details affiliated with radio telemetry based acquisition and positional changes by the individual snakes across tracking events. The dataDemographic data for toxicant based trial eradication of brown treesnakes in the USGS Closed Population on Guam, 2016 - 2020
These data are mark-recapture data procured from conducting nocturnal visual surveys and live lure based trapping for brown treesnakes in the 5 hectare enclosure called USGS Closed Population or Northwest Field North (NWFN). In addition, tissue samples were collected from brown treesnakes in order to build genetic relationships among resident individuals. The population was undergoing acetaminopheBrown Treesnake mating and reproductive success on Guam, 2004-2018
The mating and reproductive ecology of the invasive Brown Treesnake (Boiga irregularis) were generated by reconstructing a multigenerational genomic pedigree based on 654 single nucleotide polymorphisms for a geographically-closed population established in 2004 on Guam (N=426). The pedigree allowed annual estimates of individual mating and reproductive success to be inferred for snakes in the studMonitoring mortality of brown treesnakes fed an oral toxicant (acetaminophen) in an external bait placement dosing technique in the laboratory, 2017
Accidentally introduced to Guam, the brown treesnake (BTS) has extirpated nearly all native forest birds and imposed cost millions of dollars in economic damages annually. Acetaminophen is a safe and effective oral toxicant for invasive BTS, and an automated aerial delivery system (ADS) has been developed for landscape-scale distribution and snake suppression. An 80 milligram dose has proven 100%Visual Surveys and Morphometrics of Brown Treesnakes in Mariana Swiftlets caves on Guam
Visual survey data for brown treesnakes from caves with and without swiftlets. Each record (line) represents the snake sightings that occurred during a block of time, typically 1 hour at one site by searcher(s) during one search (i.e. one date). Snakes removed from caves and adjacent areas during visual surveys were then necropsied. Each record (line) represents necropsy results for a given indivi - Publications
Recent publications (2020-2022) related to USGS brown treesnake research are listed below. A complete listing of USGS brown treesnake publications is available from the button below.
Filter Total Items: 17Individual heterogeneity influences the effects of translocation on urban dispersal of an invasive reptile
BackgroundInvasive reptiles pose a serious threat to global biodiversity, but early detection of individuals in an incipient population is often hindered by their cryptic nature, sporadic movements, and variation among individuals. Little is known about the mechanisms that affect the movement of these species, which limits our understanding of their dispersal. Our aim was to determine whether tranCan we prove that an undetected species is absent? Evaluating whether brown treesnakes are established on the island of Saipan using surveillance and expert opinion
Detection of invasive species and decisions centered around early detection and rapid response (EDRR) are notorious challenges for decision makers. Detection probability is low for cryptic species, resources are limited, and ecological harm (especially for island ecosystems) can result from failure to remove invasive species due to inadequate or delayed surveillance efforts. Due to the proximity tDemographic response of brown treesnakes to extended population suppression
From a management perspective, reptiles are relatively novel invasive taxa. Few methods for reptile control have been developed and very little is known about their effectiveness for reducing reptile populations, particularly when the goal is eradication. Many reptiles, and especially snakes, are cryptic, secretive, and undergo extended periods of inactivity, traits that decrease detection probabiOlfactory lures in predator control do not increase predation risk to birds in areas of conservation concern
Context: Lethal control of predators is often undertaken to protect species of conservation concern. Traps are frequently baited to increase capture efficacy, but baited traps can potentially increase predation risk by attracting predators to protected areas. This is especially important if targeted predators can escape capture due to low trap success. Snake traps using live mouse lures may be benFemale persistence during toxicant treatment predicts survival probability of offspring in invasive brown treesnakes (Boiga irregularis)
Assessing the long-term efficacy of control methods is a critical component of invasive species management. For example, if traits related to control have significant heritability or are influenced by maternal effects, control methods may lose efficacy over time. The potential for these effects can be evaluated via parent/offspring survival analysis, which concomitantly recasts adaptive managementForaging behavior in a generalist snake (brown treesnake, Boiga irregularis) with implications for avian reintroduction and recovery
Broad foraging classifications, such as generalist or specialist forager, are generally beneficial for population management in defining expectations of typical behavior. However, better understanding as to how individual variance in behavior interfaces with management actions, such as control of an invasive predator (such as brown treesnakes; Boiga irregularis) responsible for ecological collapseBrown treesnake mortality after aerial application of toxic baits
Quantitative evaluation of control tools for managing invasive species is necessary to assess overall effectiveness and individual variation in treatment susceptibility. Invasive brown treesnakes (Boiga irregularis) on Guam have caused severe ecological and economic effects, pose a risk of accidental introduction to other islands, and are the greatest impediment to the reestablishment of extirpateDistilling professional opinion to gauge vulnerability of Guam avifauna to Brown Treesnake predation
The avifauna of Guam was devastated by the introduction of the Brown Treesnake, and the restoration of native birds would need to address the problem with eradication or suppression of BTS. With eradication of the snake unlikely in the near term, and suppression capabilities limited to specific finite areas, key information for reintroductions is how low BTS abundance will likely need to be for eaTrait heritability and its implications for the management of an invasive vertebrate
Control methods that target specific traits of an invasive species can produce results contrary to the aims of management. If targeted phenotypes exhibit heritability, then it follows that the invasive species could evolve greater resistance to the applied control measures over time. Additional complications emerge if those traits targeted by control are also inversely related to reproductive succSurface material and snout-vent length predict vertical scaling ability in brown treesnakes:an evaluation of multispecies barriers for invasive species control on Guam
The combination of snake-proof barriers and an aerial toxicant delivery system for snake suppression may allow large-scale control of invasive brown treesnakes (Boiga irregularis) on Guam. However, suppression or local eradication of several other species (e.g., introduced ungulates, cats, rodents) may be required for successful restoration and recovery of forest habitat and reintroduction of natiLocally abundant, endangered Mariana swiftlets impact the abundance, behavior, and body condition of an invasive predator
Invasive predators are known to have negative consumptive and non-consumptive effects on native species, but few examples show how the abundance of native prey may influence an established invasive predator. We compared invasive brown treesnakes (Boiga irregularis; BTS) found in caves occupied by endangered Mariana swiftlets (Aerodramus bartschi) to snakes found in nearby forests and caves withoutRecent recovery and expansion of Guam’s locally endangered Såli (Micronesian Starling) Aplonis opaca population in the presence of the invasive brown treesnake
Assessing the impacts of invasive predators on the demography and distribution of native species is critical for understanding mechanisms of species persistence and informing the design of recovery programmes. On the oceanic island of Guam, the introduction of the predatory brown treesnake Boiga irregularis after World War II caused the near-total loss of the native forest avifauna. Localised snak