VHF Tracking Data for Pacific Flyway Greater White-Fronted Geese (Anser albifrons), 1987-1991

Geographic Transformation: The original location data were in the form of X,Y coordinates. We deduced that the coordinates were UTM Eastings and Northings (NAD27 datum), many without UTM Zones. We determined UTM zones based on existing variables in the data such as date, variables that described the locations' general locale, and magnitude of the Northing. Locations were checked and corrected (see "Location Correction" Process Step below) and the quality checked UTM coordinates were transformed to geographic latitude and longitude (WGS84) coordinates.

Location Correction: When mapped, the vast majority of the presumed zones were correct; a modest number of zones needed additional correction. After UTM zones were deduced, there were numerous outlier locations. For these outliers, we evaluated whether the values could be traced to an apparent UTM-X or UTM-Y "typo" in the original data. The outliers were usually displaced directly North, South, East, or West by a factor of 1000, 100, or 10 km from the respective bird's prior or subsequent location - strongly suggesting that one digit in the Easting or Northing had been entered incorrectly. Sometimes an outlier was due to two consecutive digits in the original Easting or Northing having been incorrectly swapped. Some original location records did not have a UTM coordinate, possibly due to 1) the field crew that was VHF-tracking the tags could not acquire sufficient data for the triangulation software to derive a location estimate; or 2) the software otherwise failed to derive a location estimate. The field crew typically noted the general locale of the VHF-tracking at the time of data collection in a 2-letter variable named 'Location_General_Locale'. For records that did not have a UTM coordinate, a general estimate of the latitude and longitude, based on the 'Location General Locale' value was placed into the two variables: 'Est_Latitude_basedOnLocale' and 'Est_Longitude_basedOnLocale'.

Original Data Retention: All the original UTM coordinates have been retained in the table with the attribute names: 'Unverified_UTM_Easting' and 'Unverified_UTM_Northing'. If the original UTM coordinate was changed during the correction step described above, then the variable 'UTM_Revision_Flag' was coded = 'Y'. Also, a small number of mistakes (possibly typos) were discovered and corrected that involved things like deployment dates or codes denoting general location. The original data included several attributes that were not documented and they are retained in this dataset. The metadata will be updated if/when documentation is found.