southern end of the area, as numbers built up 

 just before the southward migrations to the 

 breeding islands. Sooty Terns were the most 

 abundant species as usual. Few were seen near 

 Oahu this month; almost all were in the south- 

 ern half of the area. Sooty Shearwaters moved 

 through the area in the highest numbers seen 

 during the fall migration, although these were 

 lower by half than those observed in the spring 

 migration. Small numbers of migrant Mottled 

 Petrels were noted as well. A small population 

 of light-phase Wedge-tailed Shearwaters still 

 remained near Oahu, but the range of the dark- 

 phase birds continued to contract southwards. 

 Only a few of the latter were seen at the south- 

 eastern corner. 



November 1964 



Total density dropped considerably from 

 October, owing mainly to large decreases in 

 Juan Fernandez and Black-winged Petrels (al- 

 though the northern limits of their ranges re- 

 mained unchanged). Wedge-tailed Shearwaters 

 remained unchanged in abundance and distri- 

 bution. Slender-billed Shearwaters appeared 

 for the first time, and their short migration 

 peak accounted for 32.5 percent of the birds 

 seen. Black-footed Albatrosses reappeared, 

 and Leach's Storm Petrels attained their nor- 

 mal winter abundance. 



December 1964 



December was the month of lowest avian den- 

 sity in the study area. All major species, i.e.. 

 Wedge-tailed Shearwater, Juan Fernandez 

 Petrel, Black-winged Petrel, and Sooty Tern, 

 were reduced in numbers. The southward mi- 

 gration of Sooty and Slender-billed Shearwaters 

 had all but ended. Only albatrosses and Leach's 

 Storm Petrel remained in large numbers, but 

 their relatively small populations in the study 

 area played a minor role in determining total 

 density, 



January 1965 



Total density increased over the low Decem- 

 ber figure. Sooty Terns accounted for 79.5 

 percent of the total population in the area, as 

 large flocks were seen once more near Oahu 

 at the beginning of their breeding season there. 

 Wedge-tailed Shearwaters and Juan Fernandez 

 Petrels decreased in abundance. Black-footed 

 Albatrosses and Leach's Storm Petrels main- 

 tained their numbers. 



February 1965 



The total density remained nearly constant. 

 Sooty Terns accounted for the greatest part of 

 the total population (73.5 percent). Large con- 

 centrations of this species were found around 

 Oahu and at the southeastern corner of the 

 study area. Wedge-tailed Shearwaters and Juan 

 Fernandez Petrels were rare. 



March 1965 



The total density of birds increased as Sooty 

 Terns became very abundant around Oahu. They 

 were much less abundant in the southern end of 

 the study area than in previous months. Wedge- 

 tailed Shearwaters reappeared around Oahu. 

 Sooty Shearwaters began their northward mi- 

 gration, although not in peak numbers. Black- 

 footed Albatrosses and Leach's Storm Petrels 

 maintained constant populations. 



April 1965 



No change occurred in total density. Sooty 

 Terns declined somewhat and were spread 

 more evenly between Oahu and the southeastern 

 corner than in March. The increase in the 

 numbers of Wedge-tailed Shearwaters was 

 mainly the result of the penetration of dark- 

 phase birds into the southern end of the area. 

 Numbers of Black-footed Albatross dropped as 

 its breeding cycle drew to a close. Leach's 

 Storm Petrels rose sharply in abundance before 

 the northward migration to breeding grounds. 

 Sooty Shearwaters rose to maximum migration 

 numbers. The migration peak in 1965 was less 

 pronounced and somewhat later than in 1964. 

 Bulwer's Petrels reappeared in the area after 

 several months' absence. 



May 1965 



The highest general density of the study was 

 recorded in May 1965 — mostly because of the 

 very large numbers of Sooty Terns observed 

 north of Oahu. In addition, numbers of Wedge- 

 tailed Shearwaters increased in the Oahu area. 

 The Sooty Shearwater migration ran its final 

 month. Juan Fernandez Petrels and Black- 

 winged Petrels reappeared in fair numbers at 

 the southern end of the study area. Black- 

 footed Albatrosses and Leach's Storm Petrels 

 declined in numbers in the study area as they 

 headed north for the summer. Several large 

 flocks of Brown Noddies were seen just north 

 of Oahu. 



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