BIRD STUDY 23 
three medium-sized Hawks that pursue and kill small birds— 
the Goshawk, the Sharp-shinned Hawk and Cooper’s Hawk. But 
these Hawks are not plentiful, and the damage they do is not 
great. The small and large Hawks, together with the Owls, 
are among the farmer’s best helpers. When you see a large 
Hawk on hay or straw stack he is watching for mice; when 
you see him perched on a tree or telephone pole he is on the 
alert to destroy pocket gophers, which dig up the alfalfa fields; 
when you find him in the orchard or by the hedge row he is 
looking for rabbits, which girdle young fruit trees; and when 
you see him on wing leisurely searching meadow or marsh 
he is hunting field mice, pocket gophers, ground squirrels and 
other pests of the farmer. The little Sparrow Hawks, so abun- 
dant in our State, live on large insects and small mammals. 
The large Owls live chiefly on night-feeding mammals, such as 
mice, rats and rabbits. ‘The little Screech Owl, whose night 
call is heard in practically every South Dakota town, is a great 
destroyer of mice. \ 
While we are benefited most by the insect-eating birds, 
the seed-eaters render valuable service in destroying weed seeds. 
As many as 9,200 weed seeds have been found in a single Mourn- 
ing Dove’s stomach. It has been estimated by the United States 
Department of Agriculture that in Iowa the Tree Sparrows 
alone, which only winter in the State, eat 875 tons of weed 
seeds annually, and that in the whole United States in 1910 the 
Sparrow family saved farm products to the value of $89,260.000. 
The economic value of birds is no longer a matter of 
speculation or sentiment. It is based on careful investigation. 
The following data, for example, is taken from reports of the 
United States Department of Agriculture. The stomach of 
a Tree Sparrow held 40 chinch bugs and 10 other species; that 
of a Bank Swallow in Texas, 68 boll weevils; the stomachs of 
thirty-five Cliff Swallows, an average of 18 boll weevils each; 
those of two Pine Siskins in Colorado, 1,900 black olive scales 
and 300 plant lice; that of a Killdeer in Texas, over 300 mosquito 
larve; that of a Flicker, 28 white grubs; that of a Nighthawk, 
34 May beetles; that of another Nighthawk, 340 grasshoppers, 
52 bugs, 3 beetles, 2 wasps and 1 spider; and that of a Duck, 
over 72,000 seeds. 
