' J920 J Brooks, Notes on American Ducks. obi 



Now the sum of all of this discussion seems to be that it would 

 be easy to wrongly identify a bird of either species from the works 

 of reference available in America, nor do those of European authors, 

 up to and including Millais' very elaborate work, give a really 

 reliable method of distinguishing the two species at all stages. 

 As their main distinction, that of the greater size of islandica, 

 only applies when it is compared with the smaller old world sub- 

 species, C. clangvla clangnla. The following attempt to differ- 

 entiate them may also prove abortive, but it works out well with 

 my series. 



This series is small, as events of recent years have interfered 

 with my plan of making a really good series of both species. Still 

 I have eleven thoroughly identified specimens of the rarer bird, 

 and have had exceptional opportunities of identifying these, 

 by taking the paired female of an undoubted male islandica, or 

 the young of the same species after watching them through the 

 summer. 



Also I have had a very much larger number through my hands, 

 and since my first introduction to Barrow's Golden-eye some 

 twenty-three years ago, I have lived in a region where it is the 

 commonest breeding duck, for the greater part of my time. 



This fact must be my excuse for attempting what is apparently 

 a rather difficult undertaking. To get correct measurements, 

 and ones that properly illustrate the differences, has not been 

 easy. First, the nail has ill-defined boundaries in many cases. 

 I have found it advisable to wet the bill to more clearly define 

 these. Second, it has been difficult to get a measurement that 

 shows the very pronounced taper of the bill in islandica; if the 

 width is taken near the tip, where it is most prominent, there 

 must be a definite point. Through the base of the nail would 

 seem to be the best, but the longer nail of islandica brings this 

 measurement further back in that species, and so makes them 

 more nearly alike than the actual shape of the bill would indi- 

 cate. Half way between nostrils and base of nail suffers from 

 the same cause, so I have had to take the measurement across 

 the anterior angle of the nostrils although the taper is not so 

 pronounced there. 



As Mr. Brewster has done (loc. cit. p. 159), I shall place the 

 characters in what I consider the order of their importance. 



