46 



farmer by destroying weeds. Sparrows, doves, bobwhites and 

 many other birds feed voraciously on the seeds of weeds during 

 autumn and winter. Sparrows are pre-eminently seed eaters, 

 and destroy vast quantities of weed seeds. Dr. Judd made a 

 thorough study of the subject. He found that a single weed 

 sometimes produced many thousands of seeds, but he also esti- 

 mated that the birds on one acre of a Maryland farm ate 46,000 

 weed seeds for their breakfast. Professor F. E. L. Beal esti- 

 mated that the tree sparrows of Iowa destroy about 875 tons 

 of weed seed annually during their winter sojourn. 1 Instances 

 have been known where sparrows have eaten practically all the 

 weed seeds in certain small tracts, but these are rare. Un- 

 doubtedly the destruction of weed seeds by birds in grass fields 

 or grain fields is a benefit. In gardens or on truck farms weeds 

 are a blessing in disguise, as they stimulate hoeing and cultiva- 

 tion, and thus bring about a surface tilth which often is essential 

 to the conservation of moisture. Therefore the utility of weed- 

 eating birds in the garden is questionable. 



BIRDS AS DISTRIBUTORS AND PLANTERS OF SEEDS. 



Recent investigations have shown that in some cases a few 

 weed seeds pass through the alimentary system of some birds 

 uninjured. In such cases the bird may become a distributor 

 and planter of weeds in a small way, and may thereby offset 

 the good done by eating seeds, but in nature seed distribution 

 is necessary to keep the soil covered with vegetation and pre- 

 vent erosion. 



Waterfowl and wading birds sometimes carry seeds of water 

 plants from place to place in bits of mud attached to their feet. 

 Jays, crows, magpies and some other species seem to ha^e a 

 mania for distributing and hiding things. No doubt many 

 seeds, especially chestnuts and acorns, are hidden away by 

 birds and never found by them again. Sudden fright often 

 causes a bird to drop food that it is carrying. All fruit-eating 

 birds scatter abroad the seeds of fruit on which they feed. Such 

 seeds are either passed uninjured through the alimentary canal, 

 or are ejected from the mouth after the pulp has been digested. 

 Birds assimilate fruit pulp very rapidly. Dr. E. A. Mearns 



i Judd, S. D.: Bulletin No. 15, Division of Biological Survey, United States Department 

 of Agriculture, 1901, p. 27. 



