FOOD BENEFICIAL IN EFFECT ON AGRICULTUEE. 27 



sparrow, junco, English sparrow, tree sparrow, Gambel's sparrow, 

 and white-throated and white-crowned sparrows. 



Among the Aveeds which are troublesome in fields, especially among 

 hoed crops, may be mentioned ragweed [Ambrosia artemisire folia), 

 sevei-al species of thegenns Polygonum — including bindweed (P. con- 

 volvulus), smartweed (P. I ajKithe folium), and knotweed (P. avicu- 

 lare) — pigweed {Amaranthus retrofiexus, and other species), nut-grass 

 and other sedges {Cyperaceob), crab-grass (Pan icum sang uinale) and 

 some other varieties of panic-grass, pigeon-grass ( ChoBtocloa viridis 

 and C. glauca), lamb's-quarters {Che.nopodium album), and chick- 

 weed {Alsine media). Every one of these weeds is an annual, not 

 living over the Avinter, and their seeds constitute fully three- fourths 

 of the food of twenty species of native sparrows during the colder 

 half of the year. Prof. F. E. L. Beal, Avho has carefull}' studied this 

 subject in the upper Mississippi Yallej^ has estimated the amount of 

 seed eaten b}^ the tree sparrow, junco, and other sparrows that swarm 

 down from Canada in the fall and feed in the rank growth of weeds 

 bordering roadsides and cultivated fields. He examined the stomachs 

 of many tree sparroAvs and found them entirel}' filled Avith Aveed seed, 

 and concluded that each bird consumed at least a quarter of an ounce 

 dailA^ Upon this basis, after making a fair allowance of the number 

 of birds to the square mile, he calculated that in the State of Iowa 

 alone the tree sparrows annually destroy 1,750,000 pounds, or about 

 875 tons, of weed seed during their winter sojourn.^ The value of 

 this AA^ork can best be appreciated hj considering the annual loss to 

 the farmer occasioned by the presence of weeds and the consequent 

 reduction of cultiA^ated crops. Mr. F. V. CoAalle, botanist of the 

 Department of Agriculture, states that "since the total A^alue of our 

 principal field crops for the year 1893 Avas $1,760,489,273, an increase 

 of only 1 percent, AA^hich might easily haA^e been brought about through 

 the destruction of weeds, would have meant a saAang to the farmers 

 of the nation of about $17,000,000 during that year alone." ^ 



Besides tree sparrows and j uncos, the most important sparrows that 

 destroy AA^eeds in the Mississippi Valley and on the Great Plains are 

 the fox sparrow, the snowflake, the Avhite-crowned sparrow, Harris's 

 sparrow, and the different longspurs. Farther south are found the 

 lark sparrows, and on the Pacific slope occur Nuttall's sparrow, the 

 golden-crowned sparroAv, and Townsend's sparroAv. East of the Alle- 

 ghenies the most active weed eaters are the tree sparrow, fox sparrow, 

 junco, white-throated sparroAv, song sparroAV, field sparrow, and chip- 

 ping sparrow. On one of the Marjdand farms Adsited in 1896, tree 

 sparrows, fox sparrows, white-throated sparroAvs, song sparrows, and 

 j uncos fairly swarmed during the month of December in the briers 

 of the ditches between the coi-nfields. They came into the open 



1 Farmers" Bull. No. 54, U. S. Dept. Agriculture, p. 28, 1897. 

 •^Bull. No. 17, Div. Botany, U. S. Dept. Agriculture, p. 3, 1896. 



