BUREAU OF BIOLOGICAL SURVEY. 347 



of about 10 per cent of the crop over an area of 20,000 acres. This 

 damage, together with lesser losses inflicted in adjoining areas, added 

 to expenditures for protection of the grain, totals about $50,000 

 as the annual loss to the valley from blackbird depredations. An 

 assistant experimented for several months with poisons, and, al- 

 though occasional big kills were made, the results on the whole 

 indicate that poisoning can not be depended upon for control. The 

 possibility of employing toxic gases has been considered, but their 

 practicability is doubtful. Meanwhile the expensive task of "bird- 

 minding" is practiced, and while this alleviates the losses it is not 

 an economical method of control. 



Wild ducks, also, finding the irrigated fields of the Imperial Valley 

 a tempting feeding ground, are especially destructive to newly sown 

 barley- and alfalfa. Examination of numerous stomachs showed that 

 barley was the source of more than two-fifths of the food of pintails, 

 about three-tenths of that of mallards, a fourth of that of widgeons, 

 and a fifth of that of green-winged teal resorting to the barley fields. 

 Thre€-tenths also of the food of the widgeon was alfalfa. Ducks 

 cause damage not only by eating seed grain and alfalfa, but by their 

 puddling method of feeding, which results in so compacting the soil 

 that nothing will grow upon it until after it has been renewed by 

 thorough cultivation. The ducks feed at night, and it has been found 

 that operating automatic flash guns, together with firing blank shot- 

 gun cartridges, affords a considerable degree of protection to the 

 crops. 



WILD FOWL DESTRUCTIVE TO SHELLFISH IN MASSACHUSETTS. 



Com]daints that certain wild ducks destroy large numbers of com- 

 mercially valuable shellfish in Massachusetts have been received from 

 time to time, the season of greatest damage being alleged to be in mid- 

 winter, particularly during January, following the close of the shoot- 

 ing season. A representative of this bureau was detailed to make 

 an investigation of the matter during the months of December, 

 January, and February. All the important shellfishing grounds of 

 the State were visited, testimony was taken, observations made, and 

 specimens collected. Of the 11 species of wild fowl of which stom- 

 achs were collected, none had eaten a significant quantity of any 

 commercial shellfish other than the common mussel and the scallop. 



Since the mussel is so abundant everywhere and has only a limited 

 sale, feeding of the birds upon it is of little consequence. The scal- 

 lop, however, has an extensive market and usually brings a high 

 price, the level of which is kept by the trade as near the maximum as 

 possible. The inquiry as to damage to the shellfish industry, there- 

 fore, resolved itself into a study of the relations of wild fowl to a 

 single species — the scallop. Of the 11 kinds of birds collected, 4 — 

 the murre. brant, red-breasted merganser or pheasant sheldrake, and 

 the purple sandpiper or rock bird — had taken no scallops; and two 

 others — the old squaw and whistler — made them only about 1 per 

 cent of their food. Scallops composed 3.17 per cent of the food of 

 24 greater scaup ducks, 5 per cent of that of 44 eider ducks, 7.83 per 

 cent of that of 12 black ducks, 20 per cent of that of 5 American 

 scoters or butter-billed coots, and 44.43 per cent of that of 219 white- 

 winged scoters or coots. 



