OPEN NESTS 171 



of the Crows and allied birds (Corvidse). As we have 

 already had occasion to point out, some of the nests 

 of these birds do not come within the present division 

 or " open " type, being concealed in holes or caves. 

 Then, again, that of the Magpies being elaborately 

 " roofed," must be reserved for the following chapter. 

 As a very typical open nest in this family, we may 

 instance that of the Raven (Corvus corax). This bird 

 breeds indiscriminately on trees as well as on rocks, 

 although in our islands incessant persecution has 

 exterminated almost every tree-building Raven, and 

 the very existence of the species as British depends 

 upon its cliff-frequenting habits during the season of 

 reproduction. The nest is placed therefore either in 

 the branches of some large tree, or upon a ledge or 

 in a fissure of the least accessible portion of some 

 cliff, marine or otherwise. Its size depends a good 

 deal upon the length of its tenancy, for the Raven, if 

 left unmolested, returns to the same nest each season, 

 adding to and repairing it just before use. The nest 

 is made externally of sticks, branches of heather and 

 pieces of turf, the soft lining to the somewhat shallow 

 egg cavity being composed of wool, roots, moss, fur 

 and hair. Some of the allied birds are in the habit 

 of cementing many of the sticks together with mud 

 or clay, as, for instance, the Rook (C. fuigelegus), this 

 material sometimes forming an inner lining, upon 

 which the softer substances are afterwards arranged. 

 The Magpies are another instance {conf. p. 215). If 



