242 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



green bug, the billbug, the boll worm,the cotton worm, and the cotton- 

 boll weevil being destroyed by hungry birds. No fewer than 66 

 kinds of birds are now known to eat the boll weevil. On the 100 

 acres in grain on a single southern farm, birds were found to be 

 destroying approximately a million green bugs daily. 



ECONOMIC STATUS OF VARIOUS OTHER BIRDS. 



Examination of bird stomachs by groups was completed for two 

 species of crossbills, two of redpolls, the pine grosbeak, the evening 

 grosbeak, three species of godwits, three of curlews, the avocet, the 

 chewink, the scarlet tanager, and the red-eyed vireo. Examinations 

 were brought up to date for the green-winged and blue-winged teals, 

 7 species of swallows, the wrens, thrashers, and mockers, the creeper, 

 4 species of nuthatches, 8 species of titmice and chickadees, the 

 wren-tit, starling, fish crow, ravens, and about 13 species of owls. 



Swallows as valuable native birds; an index to papers on the food 

 of birds, written by members of the Biological Survey; the food of 

 wild ducks in the sandhill region of Nebraska ; methods of attracting 

 birds in northwestern United States; and the care of canaries, are 

 subjects of additional manuscripts, based on this work, which have 

 been prepared for publication. 



MORTALITY AMONG WILD DUCKS IN UTAH. 



Investigations into the causes of death of large numbers of wild 

 ducks and other waterfowl around Great Salt Lake, Utah, were con- 

 tinued during the field season of 1915. Because of a light fall of 

 snow in the mountain ranges surrounding Salt Lake Valley during 

 the previous winter, water in the streams tributary to Great Salt 

 Lake was very low. In consequence large areas of marsh that in 

 normal years harbor immense numbers of wild ducks were entirely 

 dry and the birds resorted elsewhere. For this reason fewer ducks 

 died during 1915 than in previous years, but still the mortality was 

 enough to be of importance. 



In conducting the investigations, an assistant worked in Salt Lake 

 Valley from May until October. Experiments and observations 

 begun last year were carried on mainly in the great marsh areas at 

 the mouth of Bear River. Methods of practical value for the treat- 

 ment and cure of sick birds by placing them in fresh water were 

 devised that will prove useful in future outbreaks. Though it seems 

 evident that the large number of birds that die suffer from poison 

 apparently due to an alkali absorbed from stagnant water, it was 

 found that many of the affected individuals suffered from lead 

 poisoning as the result of swallowing the lead shot present in large 

 quantities about the shooting stations and blinds. Late in fall, 

 reports were received of many sick ducks at Lake Bowdoin, Mont., 

 and an assistant engaged in the work visited this locality in October 

 in order to study local conditions. 



BIOLOGICAL INVESTIGATIONS. 



As in previous years, biological investigations have been conducted 

 mainly along lines essential to the. effective administration of various 

 other activities of the bureau, including the Federal migratory-bird 

 law ; the enforcement of the Lacey Act, regulating importations and 



