630 COLLEGE ZOOLOGY 



grasshopper sparrow, and chipping sparrow feed on insects of 

 the cultivated fields, particularly during the breeding season, 

 when the nestlings of practically all species eat enormous num- 

 bers of caterpillars and grasshoppers. 



" The most evident service is the wholesale destruction of 

 weed seed. Even if birds were useful in no other way, their 

 preservation would still be desirable, since in destroying large 

 quantities of weed seed they array themselves on the side of the 

 Marshall Hall farmer against invaders that dispute with him, 

 inch by inch, the possession of his fields. The most active weed 

 destroyers are the quail, dove, cow-bird, red-winged blackbird, 

 meadow-lark, and a dozen species of native sparrows. The util- 

 ity of these species in destroying weed seed is probably at least 

 as great wherever the birds may be found as investigation has 

 s'iicwD it *o de at Marshall Hall." 



//. Domesticated Birds 



Birds have for many centuries been under the control of man, 

 and have produced for him hundreds of millions of dollars' worth 

 of food and feathers every year. The common hen was prob- 

 ably derived from the red jungle-fowl, Gallus gallus, of northeast- 

 ern and central India. The varieties of chickens that have been 

 derived from this species are almost infinite. 



The domestic pigeons are descendants of the wild, blue-rock 

 pigeon Columba livia (Fig. 470), which ranges from Europe 

 through the Mediterranean countries to central Asia and China. 

 Breeders have produced over a score of varieties from this ances- 

 tral species, such as the carriers, pouters, fantails, and tumblers. 

 Young pigeons, called squabs, constitute a valuable article of 

 food. 



Of less importance are the geese, ducks, turkeys, peacocks, 

 swans, and guinea-fowls. The geese are supposed to be derived 

 from the gray-lag goose, Anser anser, which at the present time 

 nests in the northern British Islands. Most of our domestic 

 breeds of ducks have sprung from the mallard, A nas hoscas. This 



