296. BULLETIN 191, UNITED STATES NATIONAL MUSEUM 



zoologists at Angmagsalik, having presumably wandered from the 

 Faeroes by way of Iceland. 



The hooded crow and the black carrion crow (Corvus corone) are 

 exceedingly closely allied; indeed they appear to differ in no structural 

 feature whatever, but only in coloring. Moreover, where their ranges 

 overlap they regularly interbreed, producing fertile hybrids showing 

 every intergradation of color. These considerations have led some 

 ornithologists to argue that they ought to be treated as races of one 

 species, and there is undoubtedly a great deal to be said for this view. 

 At the same time, no competent biologist nowadays can doubt that racial 

 differences frequently provide the material out of which specific differ- 

 ences evolve, and, this being so, the decision as to the precise point at 

 which two diverging races become deserving of specific rank must neces- 

 sarily be somewhat arbitrary. In the present case the two forms seem to 

 be so near the border line that considerations of convenience may be 

 legitimately allowed to carry some weight, and as it is distinctly more 

 convenient for descriptive purposes to consider them as separate species, 

 this practice, as followed by both the A.O.U. Check-list and the new 

 Handbook of British Birds, may be the more readily accepted. 



The distribution of the two birds is curious, for the range of the 

 hooded crow cuts that of the carrion crow completely into two parts 

 separated by many hundreds of miles, the carrion being the crow of 

 southwestern Europe, and absent from the rest of that Continent and 

 from western Asia, but reappearing in central, eastern, and northeastern 

 Asia. The ranges only overlap along relatively narrow zones of contact, 

 a circumstance justifiably stressed by those who would regard the two 

 forms as races of one species, and in these areas, as mentioned above, 

 they interbreed more or less freely. The hooded crow might be regarded 

 as a geologically more recent form which arose in the intermediate area 

 and has replaced the black form over a part of its range. 



The hooded crow frequents both cultivated and uncultivated country, 

 which may be fairly well timbered, but not densely wooded, or quite 

 devoid of trees. It is often seen on the seashore or along the borders 

 of lakes and estuaries. 



Courtship. — The following account has been given by C. and D. 

 Nether sole-Thompson (1940): 



While watching a flock of some fourteen birds on December 9th, 1938, the 

 trait observed by Miss E, V. Baxter and Miss L. J. Rintoul was noted, viz., 

 repeated jumps into the air and descent to the same place. Chough-like dives 

 with wings nearly closed, fluttering with dangling legs and upturned wings of 

 males (?) over females (?), and low skimming flights by flying over perched 

 birds were also observed. During these performances there was much croaking 

 from time to time. Display-flight of the male (20.3.38) is a scries of short dives 



