98 THE FOOD OF BIRDS 



THE FOOD OF BIRDS 



Food and Distribution 

 Food and Habit 

 Economic Value of Birds 



Birds and Insects 



Birds and Weeds 



Birds and Rodents 



Birds as Scavengers 



Food and Distribution. Birds consume a large amount of food and 

 they rarely store it. No one factor, therefore, exercises a greater or 

 more constant influence on their activities than the ever-present neces- 

 sity of securing a sufficient amount of the proper kind of nourishment. 



Not only are a bird's daily movements more or le& governed by 

 the search for food, with pronounced local variations in numbers, due 

 to the ripening of fruits, unusual abundance of insects, supply of car- 

 rion, etc., but the presence or absence of the species during certain 

 seasons may depend directly on the abundance or scarcity of a certain 

 kind of food. Given bayberries, and one may expect Myrtle Warblers 

 to winter in numbers near New York City; buckwheat in a pile of 

 chaff induced a flock of Mourning Doves to pass the winter at Engle- 

 wood, N. J.; the failure of the coniferous seed crop is evidently the reason 

 for the irregular occurrence of great numbers of Crossbills south of their 

 usual winter range, to cite only a few of the innumerable instances 

 showing how both the local and general movements of birds are influ- 

 enced by the food-supply. 



Food and Habit. From the Swifts, coursing the sky almost be- 

 yond the reach of vision, to the Diver beneath the waters, birds neglect 

 no spot containing food. The result is not only great diversity of fare, 

 but a correspondingly wide range in the methods, or feeding habits, 

 by which it is secured. (See under Uses of the Bill and Feet.) 



Economic Value of Birds. Interesting as we shall find the study 

 of a bird's food in relation to its distribution and habits, it is of even 

 greater importance for us to learn in what way or ways the nature of 

 its food determines its economic relations to man. X-) 



In no branch of American ornithology has greater advance been 

 made, during the past twenty years, than in the study of the value of 

 birds to man based on a knowledge of their food. This is due chiefly 

 to the investigations of the Biological Survey of the United States 

 Department of Agriculture, and also to the researches conducted by 

 certain states, notably Massachusetts, New Hampshire, and Pennsyl- 

 vania. The subject is too wide and too important to be treated ade- 

 quately here and the student is referred to the many valuable papers 

 listed beyond, particularly to those issued by the Department of Agri- 

 culture (many of which can be secured from the Superintendent of 

 Documents at Washington) and to Forbush's "Useful Birds." 



