BIOLOGICAL SURVEY. 243 



interstate shipments of birds; the maintenance of bird and mammal 

 reservations; and the economic investigations concerning the rela- 

 tions of birds and mammals to agriculture, stock raising, and for- 

 estry. The various card indexes containing information in regard 

 to the distribution and habits of the various species of North Amer- 

 ican birds and mammals, comprising a vast amount of unpublished 

 data gathered by field parties of the bureau as well as information 

 gleaned from published sources, have been very largely increased 

 during the year. These sources of information become increasingly 

 valuable with growth. 



DSTRIBUTION AND MIGRATION OF BIRDS. 



Reports on the migration of birds were received, as in past years, 

 from more than 300 volunteer observers located in all parts of the 

 United States, in addition to a considerable number from Alaska and 

 Canada. Notable progress was made in mapping the exact distribu- 

 tion of the various species of birds inhabiting North America, and 

 for this work the reports from volunteer observers have been exten- 

 sively drawn upon. A report on the distribution and migration oi 

 gulls was published; a similar report on the terns was prepared, as 

 well as a revised edition of the report on ducks, geese, and swans, 

 in which new information was incorporated; and one on the grebes, 

 loons, and auks was nearly completed. 



BIRD ENUMERATIONS. 



The results of the second bird count taken in the early summer 

 of 1915 by more than 200 voluntary observers were studied and a 

 report was prepared for publication. The third count taken in the 

 summer of 1916 by about the same number of observers has not yet 

 been critically studied, since the returns are not all in, but as far as 

 can be determined it bears out the conclusions reached from a study 

 of the work of 1915 — that where birds are protected there is a marked 

 increase in their numbers, and that intelligent and systematic encour- 

 agement, therefore, may be expected to result in a notable increase 

 in the bird population throughout the country, with corresponding 

 benefit to the farmer. 



BIOLOGICAL SURVEYS. 



Progress was made on the biological surveys of Oregon and 

 Arizona, and work on Montana was begun. A survey of Alabama 

 was nearly completed and a report on the birds of that State pre- 

 pared for publication. Field work on the survey of North Dakota 

 was finished. A report on the life zones of Wyoming was completed 

 and one on the mammals of that State was well advanced in prep- 

 aration. Eeports on the mammals and birds of New Mexico and on 

 the birds of Texas were practically completed. In the spring of 

 1916 preliminary studies of the distribution of birds and mammals 

 in parts of Georgia, and North and South Carolina were made. 



INVESTIGATIONS RELATING TO MIGRATORY WILD FOWL. 



In the summer of 1915 field studies were made on the abundance 

 and distribution of breeding waterfowl in Nebraska, in connection 

 with a special investigation of the food plants of these birds. 



