HOODED CROW 299 



modern ornithologists but recorded of the present species in Ireland 

 more than 800 years ago by the twelfth-century theologian, traveler, and 

 writer Giraldus Cambrensis, is that of carrying up mollusks and crabs 

 and dropping them on the shore or on rocks or shingle in order to smash 

 the shells. Critical observers have not generally considered that they 

 exercise any intelligent selection of hard as opposed to softer surfaces 

 for this purpose; nevertheless there is evidence that in some places they 

 have learned to utilize masonry or walls for their operations. The 

 subject is discussed by Oldham (1930). 



Voice. — The ordinary note of the hooded crow is a raucous croak. 

 It is the writer's considered opinion that there is no constant difference 

 between the voices of the hooded and carrion crows, and in this he is 

 supported by H. G. Alexander (MS.), a most careful and experienced 

 ornithologist with an excellent ear. Various observers have professed to 

 be able to detect a difference, but as to its nature their accounts are not 

 consistent. The question was also discussed some years ago in German 

 ornithological journals and the conclusion reached after critical investi- 

 gation was the same as that just stated. Reference should be made to 

 Meise (1928) and Kramer (1930). 



The note of the crow is not only more raucous but typically rather 

 less deep than the typical caw of the rook, but the range of pitch of the 

 crow's vocabulary is very much less than the rook's, namely about 600- 

 750 cycles a second as against 425-1,800 (Nicholson and Koch, 1936). 

 Nicholson further stresses a greater resonance, more deliberate timing, 

 and tendency to repeat three to four times with a long pause before the 

 next repetition. The common note might be rendered as krach, with an 

 exaggeration of the nasal sound heard in such words as "twang," and also 

 kraarrr. A higher-pitched keerk, keerk, keerk, konk, konk irresistibly 

 suggesting a distant motor horn, a short, rattling note of aggression, and 

 others may also be heard from the carrion crow, and there can be little 

 doubt that they are common to both species. The croak and variants 

 are sometimes repeated a great number of times from a tree top or some 

 other elevated position, and at times a succession of croaking and bub- 

 bling notes functioning as a kind of song may be heard. The brooding 

 female on the nest sometimes produces a very soft "crackling" sound, 

 which may continue uninterrupted for several minutes and has been 

 called a "nest-song" (R. Zimmermann, 1931). 



Behavior. — The behavior of the hooded crow is much like that of other 

 typical corvids. Its gait is a sedate walk, varied by perhaps two or 

 three rather ungainly hops if hurried. The flight is direct, with rather 

 deliberate wing beats. Where air conditions are favorable, as in crossing 

 a valley or about coastal cliffs, gliding flight may be employed to some 



