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Julian B. Fischer

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Observer-specific population indices for the USFWS Region Migratory Bird Management Arctic Coastal Plain study area. The survey consists of low-level aerial observations of waterfowl on a stratified strip transect design. The resulting data frame is several indices separated by observer and calculated using a standard ratio estimator. These data are output from the R package AKaerial and are also available within that package, see https://github.com/USFWS/AKaerial. The data used to produce these estimates contain known errors. Many but not all of these errors are corrected within the R package AKaerial. These data are presented for historical purposes only. See https://github.com/USFWS/ACP-Mapping and comments within...
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In many areas surveyed during the North American WBPHS, ground surveys are conducted in conjunction with the aerial surveys to derive annual visibility correction factors (VCFs) for the aerial survey crews, which are used during analyses to adjust for detection bias. Due to the remoteness of strata 1–12, ground surveys are not conducted there. Instead, a set of fixed VCFs by species and basic habitat type (strata 1–7 = boreal forest; strata 8–11 = tundra; stratum 12) are used. The fixed VCFs that were used through 1991 were derived from work done in WBPHS prairie strata. During the years 1985–1991, efforts were made by the FWS Division of Migratory Bird Management-Alaska Region (MBM-Alaska) to develop more appropriate...
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WBPHS_Stratum_Areas.csv is a table that lists the area measurements (in square miles) for strata 1-12, as measured and adopted by survey designers in 1974. These measurements are used by MBM-AK in analyses to produce bird abundance estimates by species and stratum.
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The WBPHS is conducted by flying an aircraft along a set of segment lines. (One or more contiguous segments comprise a transect.) The geographic coordinates in WBPHS_Segment_Endpoints.csv represent the beginning and ending points of the segment lines in Alaska and Old Crow Flats (Yukon Territory) strata 1-12. The point coordinates in this file have been incorporated into various products (e.g., a GPS waypoints file) to aid in survey-flight navigation. The coordinates are in decimal degrees, WGS84 datum. The set of segments contained in this file was established in 1964. In the years 1957-1963, the survey design included many, but not all, of these segments. Additional segments were flown in some or all years during...
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