Image from the Biodiversity Heritage Library.
Contributed by Smithsonian Institution Archives.
| www.biodiversitylibrary.org
Transcription
Storm Petrels
WRSP 94
DRSP 15
Storm Petrel sp. 90
All birds observed, with one exception, are believed to be Leach's-
type Storm Petrels; the exception being a small, all-dark bird observed
on 31 August at 32°30' N, 123°19' W. This bird represents the first pos-
sible record of a Leach Petrel (Halocyptena microsoma) in the Grid.
The distribution of storm petrels during the survey did not appear
random. Densities were high in the north and southern sections of the
Grid. Density in the central section appears low; however, these data
may be misleading. Seas were choppy during the survey of the central
portion and generally smooth during the survey on the northern and
southerly sections of the Grid. It is possible that sea conditions such
as encountered in the central section reduce the radius of visibility
evenough to explain the low numbers recorded. It is well known among field
observers that storm petrels are difficult to see in choppy seas (6-8 ft.),
but it is not possible to assign a quantitative adjustment factor to
these data to account for environment changes.
The high linear density of storm petrels in sector 7 is discussed
earlier in the report. In summary of that discussion the recorded den-
sity is higher than actual densities due to smooth seas and observations
from the skiff. Both factors increased the radius of visibility yielding
greater numbers of birds recorded.
Red-billed Tropicbird
Two birds were recorded in sector 9 of the Grid.
Red Phalarope
Sixty-nine percent of the phalaropes were recorded in the northern
section of the Grid. Birds were again recorded in the vicinity of slicks
believed to be indicative of oceanographic fronts. These slicks were
found in the east side of sector 2, as was the case on EGS 11.
The nocturnal abundance of phalaropes in the central section is of
interest. On the night of 3 August, after seeing no phalaropes during
day, ca. 25 birds were recorded during 2-1/2 hours of nocturnal ob-
ervation. The birds are attracted to the ship at night given proper
overcast conditions. But on this night the ship was drifting (essentially
remaining in one area) and such high numbers are difficult to explain.
Do the birds move primarily at night and stay on the water during the
day, or is there another explanation?
Jaegers
Parasitic Jaeger 1
Long-tailed Jaeger 1
Jaeger sp. 21