BIRDS AND THEIR DAILY BREAD. 607 



enough in its every-day life, acorns. One of the most remarkable in- 

 stances of avian providence is that related by Saussure, of the Mexi- 

 can Colaptes. The sides of the extinct crater of Pizarro, in Mexico, 

 are covered during the winter months with the dried-up hollow stalks 

 of the last year's agave-flowers, over which a yucca-tree here and 

 there casts a scanty shadow. Hither, at the time of the ripening of 

 the acorns, come large flocks of the birds with acorns, which they have 

 brought from a great distance, for no oak-tree grows within many 

 miles of the spot. Beginning at the bottom, they bore with their deft 

 bills a succession of holes, at short distances apart, in the hollow agave- 

 stems, and through them deposit their acorns in the interior cavity. 

 The acorns look, when the magazine is filled, laid one after another, 

 like the beads of a rosary. When the time of scarcity arrives, these 

 insect-eating birds hasten to their store-houses, extract the acorns 

 from them, fly with them to the yucca-trees, and, boring in the bark 

 of them holes large enough to hold the acorn, as an egg-cup holds an 

 egg, break open the fruit and eat it in comfort. Saussure avers that 

 the acorns in question are sound, and free from worms. 



Other birds, not looking so far into the future, provide only for 

 temporary wants. A species of owl, according to Naumann, feeling 

 the approach of a storm, lay up a stock of mice to last them through 

 the nights when they will be unable to hunt. When the red-backed 

 shrike has caught more than its appetite demands, it spits the surplus 

 — young birds, frogs, and larvre — on thorns ; whence it has been called 

 the thorn-turner, or, because the people believe that the number of its 

 victims is always nine, the nine-killer. Curiously enough, a relative 

 of this shrike, the Collurlo Smithii, of Africa, employs, to accomplish 

 a similar object, the more difficult method of slipping one end of a 

 plant-fiber around the victim's neck, and hanging it by the other end 

 to a bush, thereby giving its store-room a kind of resemblance to a 

 gallows-yard. Not only are these lesser special peculiarities, these 

 side-features of the bird's habits, as we might call them, determined 

 by the kind of food and the method that has to be employed to obtain 

 it, but more important and fundamental features of its life, its mi- 

 grations, its distribution, and many of the motives of its propagation- 

 history, can be traced back to them. The origin of the migratory in- 

 stinct has usually been sought in climatic causes, and in the desire to 

 avoid the cold and hardships of northern winters. This is an error. 

 The little titmice and modest wrens, which are able to find the most 

 carefully hidden larva in its winter-quarters, and can discover the 

 most minute insect-egg, and which will not disdain a berry or a seed, 

 stay with us through ice and snow ; but the larger and stronger 

 cuckoo remains in the north only while insect-life is at its height, and 

 starts early on its southward journey. The great shrike is a perma- 

 nent resident in Europe, going away only rarely, in case of dire ex- 

 tremity, but its three indigenous relatives are real birds of passage, ap- 



