Page 

 26b. Relative composition of avifauna by species group, October 1964 to 

 March 1965. Numbers in parentlieses in each sector indicate the 



percentages of total birds in each category 65 



26c. Relative composition of avifauna by species group, April-June 1965. 

 Numbers in parentheses in each sector indicate the percentages of 

 total birds in each category 66 



27. Distance-from-nearest-land isopleths superimposed on the theore- 

 tical cruise track. Palmyra Island of the Line group is the closest 

 point of land from the southwestern part of the study area 67 



28. Location of eight 5° x 4° subdivisions of the study area. Each sub- 

 division contains ca. 72,000 square miles (24.6 million ha.) 70 



29. Sea bird abundance in subareas in the study area. The squares of 

 the table repeat the geographical layout of figure 28. The upper 

 figure in each square is the density in birds per 10 linear miles 

 (18.5 km.) of observation; the lower figure is the estimated popula- 

 tion, weighted by the effective range of observation of each species. 

 Density and population figures are daily averages during each season 73 



30. Percent of sea birds seen flying in various directions in different 

 seasons. The outer circle represents 20 percent of the total; the 

 second circle 10 percent. If birds flying in one direction exceeded 

 20 percent, the bar extends past the outer circle and the percentage 

 is indicated at the end of the bar. The sample size is given in paren- 

 theses under each figure 79 



31. Percentage of sea birds observed during each hour, 1 to 7 hours after 

 sunrise and 1 to 7 hours before sunset. The dashed line indicates 

 the theoretical line if birds were observed in equal numbers each 

 hour. The number in parentheses after the species' name indicates 

 the sample size. The numbers in parentheses after a.m. or p.m. 



are the percentages of total birds seen in the morning or afternoon 82 



32. Number of birds per 30 linear miles (55.6 km.) of observation at 

 various wind speeds in increments of 4 knots (2 m. per second). The 

 number of samples at each increment shown in parentheses below 



the upper figures applies to all figures 87 



33. Number of birds seen per 30 linear miles (55.6 km.) of observation 

 at various air temperatures in increments of 1° C. The number of 

 samples at each increment is in parentheses under the upper figures, 



but pertains to all figures 89 



34. Number of birds seen per 30 linear miles (55.6 km.) of observation 

 at various water temperatures in increments of 1° C. The number 



of samples in each increment is given below the temperature 92 



35a. Distribution of birds in flocks, March-June 1964 98 



35b. Distribution of birds in flocks, July-November 1964 100 



35c. Distribution of birds in flocks, December 1964 to March 1965 102 



35d. Distribution of birds in flocks, April-June 1965 104 



36. Relative abundance of species or species groups found in flocks, 



averaged over 15 months 105 



