The antenna of one GPS receiver was carefully positioned over a marker identifying the location of one of the nest-mapping grid posts. GPS data were recorded in the receiver, while a second GPS receiver simultaneously collected data at a geodetic reference monument on the roof of UNB's Gillin Hall. Computer analysis of the data from the two receivers yielded a position for the marker with decimetre accuracy. (Andrew Smith photo)

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An EDM instrument was used to determine the relative position of the nest-mapping grid posts with respect to two of the posts positioned using GPS. (Andrew Smith photo)

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The greater scaup lays up to 12 eggs in a nest typically found in a clump of grass or sedge on islands and peninsulas in rivers and lakes. (Andrew Smith photo)