(Official (Drgzm of the Jtustntlasian (Ornithologists' (Bnion. 



Birds of a feather.' 



Vol. III.] ist JULY, 1903. [Part i. 



The Cormorants of New Zealand : a Study in 

 Variation. 



By Captain F. W. Hutton, F.R.S., Christchurch. 



ALTHOUGH everyone allows that the different kinds of animals 

 have had common ancestors, it is acknowledged to be a very 

 difficult task to draw up a genealogical tree with any approach 

 to accuracy. No one, perhaps, can realize fully this difficulty 

 unless he has himself tr ed to reconstruct some portion of it. 

 Yet the temptation to try is very strong, because we see that if 

 we could trace out the history of an order, or of a family, or 

 even of a large genus, we should at once obtain most interesting 

 information about the origin of variations. Indeed, it is only 

 by comparing a large number of pedigrees that we can ever 

 arrive at sound conclusions as to the cause of variations. 



When we feel this temptation very strongly upon us — when, 

 indeed, it becomes irresistible — we should look out for a group 

 of animals in which all the conditions of life are as simple as 

 possible ; for this removes many difficulties and uncertainties 

 out of our way. Among the sea-birds the conditions are simpler 

 than among land-birds, and New Zealand is particularly well 

 situated for their study. I have therefore chosen the New 

 Zealand . Cormorants — generally known as Shags — as a test for 

 current theories of variation ; not intending to make it a close 

 and formal investigation of the species — for which our knowledge 

 of the habits and changes of plumage of the birds is not yet 

 sufficient — but merely a light sketch, showing the way to a 

 more elaborate study at some future time. 



I must, however, say a preliminary word about pedigrees in 

 general. When only two species are concerned, we have either 

 A derived from B, or B derived from A, or both A and B derived 

 from an extinct species, C. This last is probably often the case, 

 but as we cannot reproduce the extinct species, and as probably 

 one of the new species will bear a closer resemblance to the 



