312 AGRICULTURE. 



ing bindweed (/*. convolvulus), smartweed (^P. 

 lapathifoliuin), and knotweed {P. aviculare), 

 pigweed (^Amaraiitus reti^oflexus and other spe- 

 cies), nut-grass and other sedges {Cypei^acecs), 

 crab-grass (Panicuin sanguinale), pigeon-grass 

 (^Choetocloa viridis) and (C glauca), lamb's-quar- 

 ters {^Cheuopodiuiii album), and chickweed i^Al- 

 sine 7nedia). Every one of these weeds is an 

 annual, not living over the winter, and their 

 seeds constitute fully three-fourths of the food 

 of a score of native sparrows during the colder 

 half of the year. Prof. F. E. Beal, who has 

 carefully studied this subject in the upper Mis- 

 sissippi valley, " has examined the stomachs of 

 many tree-sparrows and found them entirely 

 filled with weed seed, and concluded that each 

 bird consumed at least a quarter of an ounce 

 daily 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 sparrow annually destroys about 

 1,750,000 pounds, or about 875 tons, of weed 

 seed during its winter sojourn." * 



On a farm in Maryland " tree-sparrows, fox- 

 sparrows, whitethroats, song-sparrows, and snow- 

 birds fairly swarmed during December in the 

 briers of the ditches between the corn-fields. 

 They came into the open fields to feed upon 



* Quoted from the Year-book, 1898: "Birds as Weed Destroy- 

 ers." 



