YELLOW-BILLED MAGPIE 181 



of the two calls is almost indistinguishable. An element in this utter- 

 ance suggests the rich, harsh, scolding chaack note of Bullock's oriole. 



2. Quack? A single note, rather mild in expression, yet querulous. 

 This note has the same general timber as No. 1. 



3. Queck or kek. Sometimes uttered alone and sometimes heightened 

 from phase No. 2. The utterance has an almost absurdly weak tone. 

 It reminds the observer of the call of the black-necked stilt. It is more 

 piping than the other types of notes and is a little nuthatchlike. When 

 first heard it was written down as peip. The sounds in this note are 

 less distinct and of the three types it is least spellable and least utter- 

 able by a human being. 



Comparison of the voices of the two kinds of magpie in America is 

 difficult when the birds must be studied separately. Some observers 

 have been unable to distinguish them on this basis. Wheelock (1904), 

 however, considered the call note of the yellow-billed form as less harsh 

 and loud than that of the black-billed, and this is an observation that 

 might be anticipated after studying other habits and the surroundings 

 of the birds. 



The primitive song similar to that of other corvids is produced often 

 by yellow-billed magpies in December, January, and February, and ap- 

 parently it is a normal part of the early segments of the nesting sea- 

 son. Indications are that it has significance in the nesting habits and 

 possibly in other phases of magpie life. 



Field marks. — The yellow bill provides an easy and certain means of 

 distinguishing this species from the black-billed kind at ordinary dis- 

 tances. Its slightly smaller size is of little help bec.ause the two kinds 

 do not occur together naturally. It may be separated from other birds 

 by the general characters of the black-billed magpie. 



Predators. — The horned owl may sometimes eat magpies, but so far 

 the evidence is only circumstantial. At the Hasting Reservation, once in 

 June, 20 minutes after three magpies had gone to the roosting place, a 

 great horned owl flew up to a ridge near them where it hooted three 

 times. One of the magpies moved over to investigate and became very 

 excited, calling loudly for about four minutes before becoming quiet 

 again. Other disturbances heard at magpie roosts were thought to be 

 caused by the near presence of a horned owl. Most of these occurred 

 before the birds settled for the night or after they left their roosting trees. 



A long series of observations of accipiters and yellow-billed magpies 

 brings the conclusion that magpies must sometimes be captured by sharp- 

 shinned or Cooper's hawks. In summer and fall flocks of magpies carry 

 on almost continuous squabbles with these hawks. Usually the hawks 

 appear to take the initiative in the pursuits, but actual captures have not 



667497— 4«— 13 



