Eastern Area Cruise No. 2
and
Eastern Grid Survey No. 1
-January 1967
This report is a summary of observations and collections made
by POBSP personnel in the eastern Pacific Ocean from January 18
through January 28, 1967. (See map #1.) Participating Smithsonian
personnel included Brian Harrington (Biologist-in-Charge), Robert
DeLong, and David Burckhalter. Superior cooperation was received
from the officers and crew of the U.S.N.S. SHEARWATER (T-AG 177), and
epecially from Captain Gibson, Mr. Webber, and Mr. Wyatt. The grid
cruise track is considered to have been as closely followed as
conditions permitted, and all positions are considered accurate within
five miles. Hourly LORAN fixes demonstrated that an accurate cruise
tack was followed. As no equipment for taking bathothermographs was
available, this phase of the survey was not possible.
This report is divided into two sections: the first deals with
the Eastern Grid, and the second summarizes the non-grid observations.
Eastern Grid Survey No. 1
The Eastern Grid Survey was conducted from 0100 January 19 until
0748 January 27; 72.9 hours of diurnal observations were conducted over
690 linear miles. Diurnal observations are summarized in Table #1.
In addition 34.6 hours of nocturnal observations were conducted.
Nocturnal observations are of little significance and should be regarded
lightly as weather and moonlight conditions seemed to cause great
variations in bird activity around the ship. These observations are
briefly summarized in Table 3, and occasional reference is also made
in the species accounts.
Weather during this cruise was variable throughout the survey.
A relatively stationary high pressure system in the southern part of
the grid greatly influenced weather during the last four days, while
a passing low center during the first three days also brought weather
changes. What influence these pressure centers have on pelagic birds
is not known at present; thusly remarks on distribution of birds in
the species accounts were made without consideration of weather centers.
In reference to flocking, groups of five or more birds seen in
one sighting (fiting the POBSP definition of a flock) were noted. But
flocking in the sense of birds travelling and/or feeding together did
not seem to occur along the grid at this time of the year. The closest
simulation to flocking occurred on the 21st of January when a large
number of fulmars were observed feeding in a small area. Other
sightings of five or more birds together were almost entirely of resting
birds, particularly gulls, storm petrels, and albatross, or of the
birds following the ship. The latter group, of course, are not in
association with each other, but with the ship. Thus at this season
flocking activity appears insignificant, and hence is not included
in the tables.
For purposes of discussion, the grid has been divided into three
sections. As will be seen in Table 2, significant differences in