304 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



1. In May, 1897,^ the Dark-bodied Shearwaters off 

 Monterey were in worn and moulting plumage, as in birds 

 just after the breeding season. The sexual organs of 

 numerous specimens examined invariably displayed no func- 

 tional development, which was also the case in the summer 

 months of 1894.^ 



2. As shown in the preceding pages and in the first two 

 papers^ of this series, the migratory movements of these 

 Shearwaters increased in extent, through the summer, 

 nearly to the close of September, when there was an abrupt 

 decline, only stragglers being seen thereafter. 



3. Almost without exception, the September and Octo- 

 ber specimens secured were in fresh plumage tvith sexual 

 organs enlarged as in birds in the jlush of the breeding 

 season. 



4. During the period of absence from Monterey these 

 Shearwaters occur in the South Temperate Zone,^ breeding 

 on oceanic islands from October to March, ^ 



5. It is improbable that the Dark-bodied Shearwater 

 should be found breeding in the remote antipodes and be 

 overlooked in the Northern Hemisphere where rarer and 

 less conspicuous Petrels (like Bulwer's, Ashy, and White- 

 faced) are known to rear their young. In short, the evi- 

 dence that the Dark-bodied Shearwaters of the California 

 coast breed in the South Temperate Zone and not in the 

 tropics or in boreal regions rests upon the same foundation 

 as the evidence that the Bobolinks of Brazil breed in the 

 North Temperate Zone and not in more southern latitudes. 



The Slender-billed Shearwater, likewise, seems to be a 

 migrant from the South Temperate Zone. It breeds in 

 myriads in the vicinity of Tasmania and New Zealand ^ 

 during the southern summer, but is apparently absent from 



1 In the following pages occasional allusion is made to observations in May and 

 early June, 1897. These observations are to appear in a subsequent paper, 'California 

 Water Birds. No. V.' 



2 'California Water Birds. No. I,' p. 181. 



3 Ibid., No. I, p. 181 et seq.; No. II, pp. 3, 5> 6. 



^ Off Corral, Chili (Lane, ' Ibis,' 7th Ser., Vol. Ill, p. 312). 

 Hobart, Tasmania (Buller, Trans. N. Z. Inst., Vol. XXVI, p. 199). 

 5 Buller, Hist. Birds N. Z., 2nd Ed., Vol. II, pp. 232, 233. 

 ^Ibid., pp. 230, 231. 



I 



