NON-INDIGENOUS BRITISH BIRDS. 341 



North Atlantic It Is more wandering In Its habits, and 

 spread over a wider area, as Is the case with many other 

 species. Lastly, and perhaps most significant fact of all, 

 I have examined an example of this Shearwater from 

 Greenland, still I believe in the collection of Mr. Hargitt, 

 which is moulting Its quills and other feathers on the 

 28th of June ! This unquestionably confirms the sugges- 

 tion that this species breeds in the Southern Hemisphere, 

 and that it moults after the season of reproduction is 

 over, In its winter quarters, as so many other birds are 

 known to do. That the eggs of the Great Shearwater 

 will eventually be found on some ocean islet or coast 

 washed by the open Southern Seas amounts to an abso- 

 lute certainty. To search for them north of the Equator 

 is futile. The circumstance is quite in accord with our 

 present knowledge of the Migration of Birds. Migration 

 as a science is yet In Its earliest Infancy, and to that 

 deplorable fact must be attributed the various erroneous 

 statements that have been made concerning the geo- 

 graphical distribution of the Great Shearwater and many 

 other species of Petrels. Unfortunately they are birds 

 of nocturnal habits, especially at their breeding stations, 

 and this to a great extent helps to keep our knowledge 

 of their whereabouts so limited. 



Family PROCELLARIID.^. Genus CEstrelata. 



COLLARED PETREL. 



CEstrelata torquata {Macginivray). 



(British : Very rare abnormal migrant.) 



The late John MacgiUivray, who discovered this 

 Petrel on Aneiteum, one of the New Hebrides, and who 



