The Trade Wind Zone Oceanography Pilot Study 

 Part VII: Observations of Sea Birds 

 March 1964 to June 1965^ 



By 



WARREN B. KING, Research Curator 



Pacific Ocean Biological Survey Program 

 Smithsonian Institution 

 Washington, D. C. 20560 



ABSTRACT 



Sea birds were observed by scientists of the Smithsonian Institution's 

 Pacific Ocean Biological Survey Program on a systematic basis in the central 

 Pacific Ocean for 15 months as part of the Trade Wind Zone Oceanography 

 Program of the Bureau of Commercial Fisheries Biological Laboratory, Honolulu, 

 Hawaii. Two experienced observers alternated watches each day from sunrise 

 to sunset. Every bird sighted was identified and logged, along with the time and 

 location of observation, the number of birds in the sighting, and, when possible, 

 their age, sex, plumage, molt, behavior, direction of flight, and any other infor- 

 mation that might prove pertinent. Twenty-five birds that were captured alive 

 were banded, and 18 birds were collected to help verify sight records of species 

 seldom or never recorded previously in the central Pacific. In 3,561.1 hours of 

 observation, 13,080 sightings were made of 65,707 birds along the replicate 

 cruise track covering 34,384 nautical miles (63,610 km.) 



The distribution and abundance of each of the 51 species or field-recognizable 

 subspecies observed within the study area were treated on a monthly and sea- 

 sonal basis and discussed in the light of the island of origin and breeding phe- 

 nology of each species. The abundance of sea birds was examined in relation to 

 environmental conditions to show the extent of their association. The compo- 

 sition, distribution, and abundance of flocks of sea birds were analyzed. 



INTRODUCTION 



From February 1964 through January 1966 

 the BCF (Bureau of Commercial Fisheries), 

 Hawaii Area, conducted a pilot program as a 

 precursor to a larger scale investigation of the 

 oceanography of the Pacific Trade Wind Zone. 

 Seventeen replicate cruises were made during 

 this period on the BCF research vessel Town - 

 send Cromwell . Each cruise lasted about 20 

 days and covered a fixed track of 4,460 nauti- 

 cal!/ miles (8,264 km.) to the east, north, and 



south of the Hawaiian Islands. A report on the 

 oceanography of the Trade Wind Zone Oceanog- 

 raphy Program pilot study has been made else- 

 where (Charnell, Au, and Seckel, 1967a-f). On 

 15 of the 17 cruises, scientists of the Smith- 

 sonian Institution's POBSP (Pacific Ocean Bio- 



— Paper No. 37, Pacific Ocean Biological Sur- 

 vey Program. 



2/ 



— All distances and areas are given in nauti- 

 cal miles. One nautical mile equals 1.853 km. 



