OCEANOOROMA LEUCORHOA 



SEPTEMBER 1964 



OCTOBER 1964 



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Figure 15a. — Distribution of Leach's Storm Petrel, September 1964 to January 1965. 



Leach's Storm Petrel 

 Oceanodroma leucorhoa (Vieillot) 



Status : Abundant visitor during nonbreeding 

 season, September-May! uncommon June-July. 



Months 



Year 



1964 



1965 



Upon completion of the breeding season on 

 islands in the North Pacific Ocean in Septem- 

 ber, Leach's Storm Petrels increased in abun- 

 dance in the study area. The plateau main- 

 tained from November through March indicated 

 that the winter population in the area was nearly 

 constant. Numbers increased in April to a peak 

 as birds began to head north to their breeding 

 grounds. The increase was probably the result 

 of birds entering the study area from the south 

 while local birds were still present. In May 

 numbers decreased, and by June almost all 

 birds had returned to their breeding area. 



Distribution : No density centers can be demon- 

 strated for this species (figs. 15a, 15b). We 

 collected seven specimens. POBSP personnel 

 have collected many others south and west of 

 the area. A very small number of the birds 



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