BIRDS AS CONSERVATORS OF THE FOREST. 273 



Dr. Fisher has shown that the principal food of these birds, with a few excep- 

 tions,' consists of small noxious mammals, such as rats, mice, rabbits, etc., and 

 it is probable that they are the most potent factor in preventing the undue 

 increase of these pests. The common cotton-tail rabbit, as well as others of his 

 ilk, is a constant menace to young nursery stock of either fruit or forest trees, 

 and as these creatures are nocturnal in their habits, they feed at a time when it is 

 practically impossible to protect the trees from their depredations. But nature 

 has kindly arranged that two of our largest species of nocturnal birds — that is, 

 the great horned owl and the barred owl — should prey upon the rabbits, and so keep 

 their numbers within bounds. In most cases they would do this work effectually 

 if unmolested, but it seems impossible for a man with a gun to abstain from 

 killing an owl if a chance is presented, and then to justify himself will declare 

 that owls kill pigeons, poultry and game birds. 



That the majority of the birds of prey feed to an injurious extent upon birds 

 or poultry is a contention which has been thoroughly refuted by Dr. Fisher. 

 That they do occasionally attack poultry, and sometimes, when hard pressed, kill 

 small birds or game no one will have the hardihood to deny, but, as Dr. Fisher 

 has demonstrated, these cases constitute the exception and not the rule. The 

 normal food of the various species of hawks and owls, with two or three exceptions, 

 consists of the small mammals, mostly of the order of Rodentia, all of which are 

 more or less harmful to the interests of agriculture, and some are pests. The 

 smaller species of owls, preying as they do in the night, come in contact with 

 mice and voles, whose habits are more or less nocturnal, and find the principal 

 source of their food supply in these noxious creatures. During the winter season, 

 particularly if the snow be deep, these mice and other rodents subsist largely 

 upon the bark of young trees, which they girdle beneath the surface of the snow, 

 and in this way ruin thousands. During daylight many of these creatures are 

 captured by the various species of hawks, so that the good work of destroying 

 them is carried on throughout the whole twenty-four hours. 



Perhaps the most striking instance of the good work accomplished by birds of 

 prey is the case of a pair of barn owls that have for a number of years occupied 

 one of the towers of one of the public buildings in Washington. Dr. Fisher has at 

 various times visited this eyrie and gathered the disgorged pellets containing the 

 undigestible portion of their prey, which it is well known the birds regurgitate. 

 In all there were collected 675 of these pellets, and by a careful analysis they 

 were found to contain the bones of 1,787 small mammals, thirty-two birds and 

 two frogs, or 1,821 individual animals in all. These, it must be borne in mind, 

 were collected in the parks and the immediate vicinity of a large city, which one 



