PHAETHON LEPTURUS 



MARCH 1964 -JUNE 1965 



Figure 16. — Distribution of White-tailed Tropic- 

 bird. 



White-tailed Tropicbird 

 Phaethon lepturus Daudin 



Status: Common resident. 



Months 



Year 



1964 



1965 



This species was present in small numbers 

 every month of the year. A prolonged breeding 

 season, such as that of the birds in the Hawaiian 

 Islands, would account for the relative regular- 

 ity of sightings. 



Distribution : Birds were frequently observed 

 near the mainHawaiian islands (fig. 16). Other- 

 wise, distribution was random throughout the 

 study area north of lat. 15° N. The southern 

 third of the area accounted for only 15 birds 

 (10 percent), even though roughly one-third of 

 the observation time was spent there. All birds 

 recorded south of lat. 15° N. were seen between 

 February and June. 



Red-tailed Tropicbird 

 Phaethon rubricauda Boddaert 



The numbers of Red-tailed Tropicbirds were 

 nearly constant from March 1964 through No- 

 vember 1964; they decreased in December, and 

 remained low in January and February. Num- 

 bers increased again in March 1965 and re- 

 mained at the higher level until the end of the 

 study. 



The breeding season begins in late February, 

 and chicks are fledged by November on both the 

 leeward Hawaiian chain and the Phoenix and 

 Line groups. The population at these breeding 

 sites is smallest December through February. 

 Since fewer birds were seen at sea during these 

 3 months than during the rest of the year, a 

 postbreeding dispersal out of the study area is 

 indicated. 



Distribution : Red-tailed Tropicbirds were dis- 

 tributed evenly throughout the study area in all 

 months (fig. 17). 



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