28 THE RELATION OF SPAREOWS TO AGRICULTJ^RE. 



fields to feed on weed seed, and were most active where the smart- 

 weed formed a tangle on low ground. Later in the season the place 

 was carefully examined. In a cornfield near a ditch the smartweed 

 formed a thicket more than 3 feet high, and the ground beneath was 

 literally black with seeds. Examination showed that these seeds had 

 been cracked open and the meat removed. In a rectangular space of 

 18 square inches were found 1,130 half seeds and only 2 Avhole seeds. 

 During the ensuing season no smartweed grew where the sparrows 

 had caused this extensive destruction. Even as late as May 13 the 

 birds were still feeding on the seeds of these and other weeds in the 

 fields. Sixteen sparrows were collected on that date, and 12 of these, 

 mainly song, chipping, and field sparrows, proved to have been eating 

 old weed seed. So thoroughlj^ had the work been done that diligent 

 search showed only half a dozen seeds in the field where they had been 

 feeding. The birds had taken practicall}^ all that were not covered; 

 in fact, the song sparrow and several others had scratched up much 

 buried seed. 



In the greater part of the United States most of the song sparrows, 

 and all but a ver}^ few of the dickcissels and field, chipping, vesper, 

 lark, Harris, and grasshopper sparrows, are replaced in winter by 

 snowfiakes, juncos, longspurs, fox sparrows, white-throated spari'ows, 

 and Avhite-crowned sparrows. All these birds have much the same 

 food habits, but the}" differ in the quantity and kind of seed the\" eat. 

 Thus, the tree sparrows, or Svinter chippies,' and longspurs feed 

 largely on seeds of grasses, especially those of pigeon-grass, crab- 

 grass, and allied species, while the white-throated sparrow in the 

 Eastern States, Nuttall's sparrow in the Pacific coast region, the 

 snowflake of the northern tier of States, and the white-crowned spar- 

 row, so abundant in the central part of the United States, particularly 

 relish amaranth and lamb's-quarters. The white-throated sjjarrow is 

 also a great consumer of ragweed, and outranks in this regard ever}' 

 other sparrow except the junco. The song sparrow shows a liking 

 for i3oh'gonums, and in the destruction of the weeds of this genus 

 is the most valuable bird whose food habits have thus far been inves- 

 tigated. 



During cold weather the natiA^e sparrows require an abundance of 

 food for warmth, and it is habitual with them to keep their stomachs 

 and gullets heaping full — so full, in fact, that if a bird be killed and 

 shaken by the feet scores of seeds rattle out on the ground. This 

 habit, coupled with their gregariousness, greatl}^ increases their 

 efficiency. 



SUMMARY. 



It is hardly to be expected that such seed eaters as sparrows should 

 destroy as great a quantity of insect pests as birds that are entirely 

 insectivorous. When it is found that in the food of the native spar- 

 rows such pests average but 25 percent, it is only what might be 



