INTRODUCTION. 



13 



Many of the replies to Circular 9, and to other special letters of 

 inquiry, contained detailed accounts of injury to crops, interesting notes 

 on the habits of the spermophiles, and various means employed for 

 their destruction. A few extracts from these letters are given under 

 each species and present the case as seen by those most deeply inter- 

 ested. Some of the reports may be prejudiced, but in many the good as 

 well as the evil traits of the animals are recognized. 



Field work. — Competent men employed by the Division as special 

 field agents have been sent to parts of the country from which com- 

 plaints had been received concerning the ravages of spermophiles. 

 In some cases the reports of damage to crops were found to be exag- 

 gerated or attributed to the wrong species, and such errors were 

 corrected by means of these field investigations. Specimens of the 

 animals were collected for identification and comparison, their abund- 

 ance was carefully estimated, their geographic range, details of distri- 

 bution, breeding habits, food habits at different seasons of the year, 

 and the various methods employed for their destruction were care- 

 fully studied, and a large number of stomachs was collected and 

 preserved in alcohol for subsequent examination in the laboratory. 



Nor were the investigations limited to spermophiles and pocket 

 gophers, for some attention was given to the habits of their natural 

 enemies, particularly the birds and mammals that prey upon them. In 

 examining the stomachs of hawks and owls remains of spermophiles 

 were frequently found, and in some instances the birds were seen in 

 the act of catching or eating them. Badgers were found to spend con- 

 siderable time in digging ground squirrels and pocket gophers out of 

 their holes, and to be of no small importance in holding in check the num- 

 bers that otherwise would add their increase to present hordes. Other 

 animals also were found to feed upon them, as mentioned in detail later e 



Laboratory icorJc. — Though the contents of many stomachs were 

 examined in the field such examinations were made mainly for the pur- 

 pose of learning the sort of food selected by the spermophiles so that 

 their habits might be more fully understood. The stomachs of most 

 of the specimens were preserved in alcohol, and each was labeled 

 with a tag of parchment paper bearing a number in carbon ink. A 

 corresponding number was entered on a schedule and followed by the 

 name and sex of the animal, place where taken, date, hour at which 

 killed, and such notes as might help in understanding any peculiarity 

 of food found in the stomach. Such notes were usually a brief state- 

 ment of the animal's surroundings when killed; as, 'near wheat field,' 

 'in meadow,' 'on open prairie,' or 'on edge of cornfield.' These pre- 

 served stomachs, together with the accompanying schedules, were for- 

 warded to the Department for critical examination. Each stomach 

 was cut open, the contents spread out on a plate, and enough water 

 added to wash out the fine sediment. Among the coarser materials 

 were found hairs, feathers, the outer coats of grains, shells of seeds, 



