# Obs. - 8X1 
(See Graph. IOC) 
3irds were recorded in all 15 pelagic and interisland sections 
rather widely differing densities 
but 
Linear Density 
-No. Sections 
General Area 
.003 - .014 
5 
Phoenix Islands vicinity; southern 
north pelagic 
.022 - .103 
5 
Northern north pelagic, southern 
Line Islands 
.481 - 1.029 
3 
Fiji; Christmas; (Samoa) 
4.442 - 4.777 
2 
Northern Line Islands 
.131 
15 
• 
The six main density centers are, in approximate order of abundance 
l) Northern Line Islands; 2) Samoa; 3) Fiji; 4) Kawaiians; 5) Phoenix 
Islands; 6) Southern Line Islands. 
The concentration of birds in the 12° N. belt was more pronounced 
than the similar patterns noted from the other two boobies. Roosting 
red-foots are common on Johnston Atoll and breeding red-foots abundant 
on Palmyra. I am not aware if a positive connection has been made, but 
it seems likely that immatures, at least, disperse regularly to Sand- 
Johnston, probably via the 12° N. belt. 
In the Fiji area light-phase birds appear to be as common as dark- 
phase birds. Around Samoa there are more dark than light, but not to 
the virtual exclusion of the light-phase that occurs in the Phoenix and 
Lines. The correlation of phase and size with latitude appears to hold 
on both sides of the Equator 
The same correlation, but with Blue-faced Booby abundance is 
equally as striking. The adaptive advantages gained are probably a 
function of competition but the mechanism is unclear (character dis¬ 
placement?). The blue-faced/red-foot relationship is a good example of 
general adaption vs specific adaption; the red-foot being the more 
generalized in nesting requirements, range, phenotypic plasticity, etc. 
Great Frigatebird # Obs. - 20 
Lesser Frigatebird # Obs. - 30 
Frigatebird sp. Obs. - 72 
• Total - 122 
Frigates are found l) around their breeding islands; 2) in associa¬ 
tion with tern (sooty) flocks. The data indicates no other factors in¬ 
volved in their distribution or movements. The chief ecological '"role" 
