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Bjorn Lardner

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Nocturnal visual encounter survey data conducted by 29 searchers over 17 transects obtained during a Brown Treesnake rapid response deployment to island of Saipan in 2016. Surveys took place in the vicinity of the Saipan airport and Dandan village (ca. 15.127°N, 145.735°E) from 06 January to 13 March 2016, 6–7 nights/week but with a break in surveying from 26 January through 21 February. During Brown Treesnake searches over 386.8 kilometers, we collected data on selected vertebrate taxa (lizards and small mammals, both potential snake prey) recorded from survey transects with similar vegetation structure (secondary forest dominated by the introduced leguminous tree Leucaena leucocephala; emergent trees were partially...
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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.
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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 application for each transect (Transect ID). Each project used a different type of attractant, either a live-mouse lures in snake traps or liquid fish fertilizer scented spray. Surveys were conducted in a 5-ha geographically closed population on Guam. Teams of two observers conducted night-time surveys from February 1 to...
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