DIVIsroN OF BIOLOGICAL SURVEY. 161 



but pass the winter in the Tropics, and has undertaken to workout the 

 winter distribution of these species, and ascertain, so far as data will 

 permit, the routes they 1 ra verse in passing to and from their breeding 

 grounds. This investigation promises to bring to light many facts of 

 interest to the student of bird migration, and it is unfortunate that 

 I u-esent appropriations will not permit a more complete elaboration of 

 the data on hand. 



In this connection it should be stated that much valuable material 

 in the form of notes and original observations on birds and mammals 

 has been brought together by the Division, but still remains unpub- 

 lished. Provision should be made for publishing some of this materi al, 

 which has been collected at considerable expense, so that it may be 

 made generally available. 



DESTRUCTION OF PRAIRIE DOGS. 



During the year complaints concerning the depredations of prairie 

 dogs have been received from about 325 correspondents in the plains 

 region of the West. These complaints came from nearly 300 localities, 

 distributed chiefly in the States of Colorado, Kansas, Montana, 

 Nebraska, South Dakota, Texas, and the Territory of Oklahoma, and 

 indicate that in many sections of these States the destruction of prairie 

 dogs is one of the most serious questions confronting the farmer or 

 cattle owner. In the last annual report attention was called to the 

 necessity for a thorough investigation of the subject, and the need of 

 making provision for carrying on the work; but the necessary appro- 

 priation was not made by Congress, and the Division is therefore 

 unable, at present, to undertake a comprehensive study of the 

 question. 



Owing to the numerous complaints received, however, and the 

 urgency of the demands for information on this subject, a preliminary 

 investigation will be made in the States of North and South Dakota, 

 Kansas, and Nebraska, and some work will also be done in Texas. 

 The data thus far secured by the Division will be utilized in the prep- 

 aration of a report to be published at an early date. The main prob- 

 lem is to ascertain the poison which may be used most effectively for 

 this purpose, and the minimum cost at which prairie dogs may be 

 destroyed under various conditions. It is well known that bisulphide 

 of carbon will destroy the animals, but the high price at which it is 

 sold in many places in the West prevents its use and gives rise to a 

 general demand for a cheaper and equally effective poison. One great 

 difficulty encountered in using poison is that prairie dogs feed mainly 

 on herbage, and refuse ripe grain when grass or similar food can be 

 obtained. The problem, therefore, resolves itself practically into three 

 phases: (1) Obtaining bisulphide of carbon at lower rates; (2) dis- 

 covery of some bait which will render the use of strychnine, cyanide of 

 potassium, and similar poisons effective at any season; or (3) the dis- 

 covery of some substance or combination of substances which will be 

 cheaper than bisulphide of carbon or strychnine, and at the same time 

 equally effective. On the solution of this problem depends the success 

 or failure of many residents in the West who are attempting to culti- 

 vate lands in regions infested with prairie dogs. 



Prairie dogs occur from Texas to Montana and from Kansas to 

 Arizona, so that nearly a dozen States are interested in the destruc- 

 tion of the pest. This fact alone shows the importance of providing 

 means for a thorough investigation of the whole question of prairie- 

 dog destruction. 



AGR 1901 11 



