SO GLOBEC, BG243 Predator Survey Methods for NBP0103 and NBP0104
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.
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.
Literature Cited
Heinemann, D. 1981. A rangefinder for pelagic bird censusing. J. Wildl. Manage. 45: 489-493.