Bird’s Food Habits

The practical value of birds to man, whether helpful or harmful, depends chiefly on their food habits. Some of their food consists of things injuri­ous to man, such as insect pests, weed seeds, and rodent pests, while some consists of things valuable to man, such as fruit and grain: so that the exact economic status of a bird is determined by a careful study of its food habits.

The United States Bureau of Biological Survey. The first systematic and thorough study of the food habits of birds began in 1885, when the National Government established a section of economic orni­thology whose purpose was to investigate the food habits, distribution, and migration of North Ameri­can birds and mammals in relation to agriculture, horticulture, and forestry.

This was later given the title of Bureau of Biological Survey. Its work upon the economic value of birds has been along three lines: (1) to determine as accurately as possible the food of birds of economic importance; (2) to act as a court of appeal to investigate complaints concern­ing depredations of birds on crops; (3) to diffuse the results of its work and to educate the public as to the value of birds.

Since its formation, the Bureau has collected a large mass of facts regarding the food habits of over four hundred species of birds and has published the results of its investigations in bulletins printed by the Government, some given away, others sold at nominal prices. Some conception of the work of the Bureau may be gained by looking over the partial list of bulletins given on pages 318-19.

This work has steadily grown in importance and to-day the Bureau is one of the most serviceable divisions of the Department of Agriculture, employing eleven men in the work on economic ornithology.

Methods of determining food of birds. Three methods have been used to determine the food hab­its of birds: (1) field observations of living birds to observe the kinds of foods taken and the amounts; (2) study of birds kept in captivity; (3) examina­tion of the contents of birds' stomachs after the birds have been killed.

Field observations. In order to determine a bird's food from a study of the living bird, it is necessary to get close to the bird or use a pair of field-glasses, and even then it is difficult to determine exactly the specific nature of the food. This method can best be used in studying the food of nestlings. The parents bring food frequently to the same spot and one is able to approach close to the nest. Some observers place a small tent within arm's length of the nest and watch the bird from within the tent. The birds usually become accustomed to the presence of the tent and come and go as usual.

The number of times that the young are fed may thus be learned. The young may be weighed each day, and thus some idea obtained of the increase in weight and of the amount of food eaten.

[CaRP] XML error: not well-formed (invalid token) at line 9