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 individual.

The dataset consists of two spreadsheets that contain brown treesnake data (location, perch taxa, perch height, time of detection, whether visible or not, and size of snake) collected during both visual surveys and radio telemetry within a 55-ha enclosure on Guam.

The dataset consists of two spreadsheets that contain brown treesnake data (location, perch taxa, perch height, time of detection, whether visible or not, and size of snake) collected during both visual surveys and radio telemetry within a 55-ha enclosure on Guam.

These data were generated during a USGS Rapid Response for brown treesnakes (Boiga irregularis) on Cocos Island Guam (Islan Dåno’, Guåhan in CHamoru). They represent data collected during nocturnal visual surveys for brown treesnakes and data associated with captured snakes, effort during visual surveys as time and distance, as well as lizards, birds, and bats encountered during transect surveys. These data represent all data collected from the onset of the rapid response in October 2020 through a typhoon that caused major site disturbance in May 2023. Data represent only USGS efforts during the specified time period. Additional data may be available for other organizations operating during the specified time period.

These data were generated during a USGS Rapid Response for brown treesnakes (Boiga irregularis) on Cocos Island Guam (Islan Dåno’, Guåhan in CHamoru). They represent data collected during nocturnal visual surveys for brown treesnakes and data associated with captured snakes, effort during visual surveys as time and distance, as well as lizards, birds, and bats encountered during transect surveys. These data represent all data collected from the onset of the rapid response in October 2020 through a typhoon that caused major site disturbance in May 2023. Data represent only USGS efforts during the specified time period. Additional data may be available for other organizations operating during the specified time period.

Data were collected in association with locations of standard brown treesnake traps on Guam at location prior to suppression or control efforts and after control had occurred. In all cases study sites were closed or semi-closed populations of brown treesnakes. Habitat data focused on type and structure of the habitat within 10-m of the trap.

Data were collected in association with locations of standard brown treesnake traps on Guam at location prior to suppression or control efforts and after control had occurred. In all cases study sites were closed or semi-closed populations of brown treesnakes. Habitat data focused on type and structure of the habitat within 10-m of the trap.

We evaluated three walking paces to estimate (1) how snake detection rate per unit distance changes with increasing pace, and (2) how total number of snakes found by the end of a night of surveying varies with pace when the amount of surveying time per night is held constant. For a “fast” pace we searched the 220 meter-long transect in 10 minutes, corresponding to a walking pace of 1.32 km/h, whereas for a “medium” pace we searched 17.5 minutes, corresponding to a pace of approximately 0.75 km/h. The “slow” pace was the 30 minutes (0.44 km/h) the standard previously adopted for work on Guam. Perch height and sizes of detected snakes were recorded for the three paces.

We evaluated three walking paces to estimate (1) how snake detection rate per unit distance changes with increasing pace, and (2) how total number of snakes found by the end of a night of surveying varies with pace when the amount of surveying time per night is held constant. For a “fast” pace we searched the 220 meter-long transect in 10 minutes, corresponding to a walking pace of 1.32 km/h, whereas for a “medium” pace we searched 17.5 minutes, corresponding to a pace of approximately 0.75 km/h. The “slow” pace was the 30 minutes (0.44 km/h) the standard previously adopted for work on Guam. Perch height and sizes of detected snakes were recorded for the three paces.

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_2020.csv) with their associated credibility score of 1-5 (5 = completely credible) defined by a panel or small group of Brown Treesnake experts. Trapping surveillance efforts used a modified minnow trap as a snake trap. Traps are suspended horizontally from natural vegetation or fences 1-1.5 meter (m) off the ground. Within each trap, a chamber houses and protects a live attractant mouse. Traps are checked each morning, and the grain mix and potatoes providing food and water for lure mice are replenished as needed. Dead mice are replaced immediately when possible, or within two days; dead mice have been shown to be roughly as attractive as live mice for the first 2-3 days. Traps are deployed along transects-which may be the same transects where nocturnal visual surveys occur-and are spaced roughly 20-40 m apart. Visual surveys occur along forest edges, roadsides, and forest interior (via measured and flagged transects). Observers use headlamps to search for snakes in the vegetation or on the ground. Survey transects are sized so that observers can complete one transect per hour (approximately 450 m/hour(h)) and capped at four transects per searcher per night to avoid searcher fatigue. Observers record start and end times, total actual search time, all vertebrates detected (to gain baseline knowledge of snake prey abundance), and distance in kilometers traversed. Surveys begin 30 minutes after sunset. Since 2004, Commonwealth of the Northern Mariana Islands residents have been implored by radio jingles, posters, and trucks with prominent signage to immediately report sightings of snakes. The islands have a Brown Treesnake Hotline with a memorable number (28-SNAKE) to facilitate reporting. Non-confirmed reports of snakes prior to 2004 were obtained via natural resource and port authority agency memos and memory.