ITINERARY 
07 November 
10 November 
03 December 
16 October, 1967 
1190 hours (+7 time) 
2359 
1100 
Depart San Diego, Calif. 
Arrive Manzanillo, Mexico 
Depart Manzanillo 
Arrive San Diego 
ca. 0200 
The following report summarizes bird and mammal observations conducted 
aboard the R/v DAVID STAR R JORDAN during EASTR0PAC Monitor Cruise No. 50 
from 17 October to 03 December, 1967- During this period diurnal observa¬ 
tions were maintained for 297*9 hours over 3^-65 nautical miles. A total 
of 14-463 seabirds was recorded. No observations were made when the ship 
was "on station", and collections were restricted to times when they would 
not interfere with primary objectives of the cruise. 
In this report the cruise track (see map one) has been divided into 
water-type areas (see map two) in order to facilitate discussion. These 
divisions are based primarily on oceanographic differences, but occasion¬ 
ally avian differences were used. 
During October and November the distribution of birds within the area 
covered by the monitor cruise was quite graphic, but as little summarized 
data are available at present, no explanations beyond very crude correlations 
will be attempted. However the reader is urged to compare species densities 
and distribution carefully, especially for tropicbirds. Wedge-tailed Shear¬ 
water, and species in the genus Pterodroma . From these distributions it 
appears that the cruise track transversed rather prominent ecological 
zones, especially In the western portions of the cruise. Additional dis¬ 
cussions pertaining to ecological factors will be included elsewhere in 
this report. For now it should be mentioned that few patterns of abundance 
were noted within a single species which could be correlated to specific 
oceanographic or biological data as available in crude form at the time 
of this report. This is not to say that such patterns did not exist, but 
rather is intended to suggest that they were obscured in some areas by the 
influence of various combinations of environmental variables as well as 
variable responses by different species to habitat changes. 
METHODS 
Observations were maintained from the flying bridge which afforded a 
360 degree horizon and an excellent angle for identification of birds 
fairly close to the ship. Because I was the only P.O.B.S.P. observer a- 
board, it was not possible to maintain continuous binocular surveillance 
during all daylight periods. Thus sightings were largely of birds which 
could be seen with the unaided eye with binocular support only for identi¬ 
fication. Hours of observation were limited to daylight periods when the 
ship was underway. 
