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Surveillance and reports of Brown Treesnakes on Saipan, 1980-2020

Metadata Updated: September 16, 2025

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.

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Created Date September 13, 2025
Metadata Updated Date September 16, 2025

Metadata Source

Harvested from DOI USGS DCAT-US

Additional Metadata

Resource Type Dataset
Metadata Created Date September 13, 2025
Metadata Updated Date September 16, 2025
Publisher U.S. Geological Survey
Maintainer
Identifier http://datainventory.doi.gov/id/dataset/usgs-60b80c52d34e86b93887588c
Data Last Modified 2021-12-09T00:00:00Z
Category geospatial
Public Access Level public
Bureau Code 010:12
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Metadata Catalog ID https://ddi.doi.gov/usgs-data.json
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 55f238be-f46b-4258-a9b7-0299280dce14
Harvest Source Id 2b80d118-ab3a-48ba-bd93-996bbacefac2
Harvest Source Title DOI USGS DCAT-US
Metadata Type geospatial
Old Spatial 145.6787, 15.0761, 145.8400, 15.3000
Source Datajson Identifier True
Source Hash d3ff059899a9a55d298ff31f867c261f7b9e66d831686e2f0ef917c53df82755
Source Schema Version 1.1
Spatial {"type": "Polygon", "coordinates": 145.6787, 15.0761, 145.6787, 15.3000, 145.8400, 15.3000, 145.8400, 15.0761, 145.6787, 15.0761}

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