210 DEPARTMENTAL KEPORTS. 



zoiu s, therefore, is one of grejit detail, and is made still more difiicult 

 by the absence of accurate topographic base maps, except of the areas 

 already mapped by the United States Geological Survey. B'or some 

 years the Biological Survey has been at work in C-alifornia, doing as 

 much each yenv as its limited means have permitted. During the past 

 season sections were studied on both slopes of the Sierra Nevada — 

 from Mono Lake to Owens Valle3M:)n the east, and from Kaweah River 

 to the Tuolumne on the west — and in Riverside and San Diego counties, 

 by parties in charge of the chief of the Division. The field parties in 

 Texas, in charge of Vernon JJailey, chief field naturalist, visited, 

 among other localities, the Chisos, Davis, and Guadalupe mountains, 

 1 he forested swamps of Sabine River, and the open Staked Plains, 

 'i'lie work in the Guadalupe Mountains was extended into New Mexico, 

 where parts of the Pecos Valley and Sacramento Mountains were 

 studied. As in previous years, the field work in Mexico was in charge 

 of E. W. Nelson, and investigations were carried on in the States of 

 Tamaulipas, Nuevo Leon, and Coahuila, where much valuable mate- 

 rial was collected. The exploration of the Great Slave Lake region 

 in Canada, which was barely commenced in the latter part of the last 

 fiscal year, was carried to a successful termination by Edward A. 

 Preble. Much important information was obtained and extensive col- 

 lections were secured. As on his previous trip to Hudson Bay, Mr. 

 Preble was heartily welcomed and given substantial assistance l\y the 

 officers of the Hudson Bay Company. Without this cordial coopera- 

 tion the expedition might easily have failed. 



In the Great Plains region prairie dogs have greatly increased, 

 owing to the extension of ranching and the destruction of their natural 

 enemies. Their depredations are widespread, and comi^laints and 

 requests for assistance have come to the Department from hundreds 

 of localities. In order to obtain accurate information, an assistant, 

 Wilfred H. Osgood, Avas sent to Kansas, Nebraska, North Dakota, 

 South Dakota, and Montana to examine the conditions and to experi- 

 ment with bisulphide of carbon and other poisons with a view to 

 finding some cheap as well as effective remedy against tliis pest. 

 Similar investigations were carried on in Texas by Vernon Bailey and. 

 H. C. Oberholser, but lack of funds prevented field experiments in 

 poisoning in winter and early spring, when poisons are most freely 

 taken. The present status of the subject is summarized in a paper 

 by the chief of the Division on "The prairie dog of the Great Plains," 

 in the Yearbook of tlie Department for 1901. 



ECONOMIC ORNITHOLOGY. 



The work of the economic section during the fiscal year ending June 

 30, 1902, as in previous years^, has consisted of two distinct parts — 

 laboratory work and field work. Laboratory work consists in the 

 examination of stomachs and crops of birds and the tabulation of 

 results. Field work consists in observing the food habits of birds in 

 the field to learn as fully as possible upon what certain species feed, 

 where the}' feed, and when they feed, and also what foods are most 

 abundant and most easily procured ; in other words, to observe every 

 circumstance connected with the food habits, so as to ascertain if 

 possible whether 'apparently favored food is eaten through preference 

 or necessity. During the year there have been received from mis- 

 cellaneous collectors 3,972 stomachs of birds. In addition to these, 

 Prof. S. A. Forbes, of Champaign, 111., has presented to the Biological 



