Seabird abundance and distribution within the SO GLOBEC study area was investigated using daytime and nighttime (using night vision viewers) survey work. We also recorded seal observations made within the transect area. Nighttime surveys were designed to complement daytime surveys.
Seabird Daytime Surveys
Strip transects were conducted simultaneously at 300 m and 600 m widths for birds. Surveys were conducted continuously while the ship was underway within the study area and when visibility was >300 m. For strip transects, two observers continuously scanned a 90� area extending the transect distance (300 m and 600 m) to the side and forward along the transect line. Binoculars of 10X and 7X magnification were used to confirm species identifications. The 7X pair of binoculars also included a laser range finder. Ship followers and bird observed to be attracted to the ship were noted at first occurrence. These observations will be down-weighted in the analyses because these individuals may have been attracted to the ship from habitats at a distance from the ship. For each sighting, transect (300 m or 600 m), species, number of birds, behavior, flight direction, and any association with visible physical features, such as ice, were recorded. Distances were measured either by a range finder device as suggested by Heinemann (1981) or by the laser distance finder (when in the ice). Marine mammal sightings within the transect were also recorded.
Surveys were conducted from an outside observation post located on the port bridge wing of the RVIB N.B. Palmer. When it was not feasible to conduct surveys from this observation post, we surveyed from the inside port bridge wing.
Seabird Nighttime Surveys
ITT 200/210 Binocular Night Vision Viewers were used during one half-hour survey periods while on the survey grid. Surveys were a minimum of an hour apart. Observations were made from the bridge wing during NBP0104 and outside, from a dark area on the 01 deck, during NBP0103. Observers scanned back and forth looking for birds. Species and behavior of the bird was recorded for each observation. Observations were not conducted when visibility with the night vision viewer was less than 100 m from the ship.