KEPORT OF THE SECRETARY OF AGRICULTURE. XCI 



others warm enough for ahiionds, raisin grapes, and citrus fruits. 

 And in the case of some of those in which the same crops may he cul- 

 tivated with equal success, these crops mature at widely different dates. 

 Thus oranges ripen in southern California from January to April; on 

 the Santa Barbara plain, in July and August; at Orovilie, in Nov^ember 

 and December. Similarly, peaches mature at different points in north- 

 ern California from May to September, and in Los Angeles as late as 

 November. (Cherries are ready for market in Vaca Valley in March 

 and April, while in neighboring vallej^s they do not ripen until May 

 and June. The great commercial importance of these differences in 

 time of ripening of fruits is obvious. 



The native fauna and flora of a region afford a suggestion as to its 

 climatic peculiarities and agricultural possibilities, assisting one to con- 

 clude what farm crops and varieties of fruit will or will not be likely 

 to succeed in a particular place. The Biological Surve}'^ is making a 

 critical stud}' of this subject, and is engaged in the preparation of maps 

 showing the natural distri})ution of the faunal and floral areas and con- 

 sequent courses of the crop belts, and is also preparing lists of the par- 

 ticular kinds and varieties of crops and fruits likely to succeed in each. 

 The labor of tracing the zone boundaries in California is one of infinite 

 detail, and is rendered still more difficult by the absence of accurate 

 topographic base maps, except of the areas already mapped b}^ the 

 United States Geological Survey. 



In addition to the work in California and Texas, some field work 

 has been done in Montana, the Dakotas, Nebraska, Kansas, Indian Ter- 

 ritor}^, New Mexico, Mexico, and Canada. 



THE PRAIRIE DOG SCOURGE. 



The extension of ranching on the Great Plains has led to serious, 

 widespread, and reiterated complaints of steadily increasing losses 

 from the depredations of prairie dogs. The increase in these pests is 

 the natural result of the destruction of their enemies, chiefly co3'otes 

 and the larger hawks. Assistants were sent to various points in the 

 afflicted area, from Montana to Texas, and much information was col- 

 lected. As a result a circular of directions for the destruction of 

 prairie dogs has been published, and an article on the subject was con- 

 tributed to the Yearbook for 1901. 



Section of Economic Ornithology. 



During the year field work on the food habits of birds has been 

 carried on in California and Maryland, and the stomachs of considera- 

 bly more than 2,000 birds have been examined in the laboratory. Of 

 these, 1,000 were of the game birds, 500 of sparrows, and the remain- 

 der distributed among other groups of economic value. A bulletin on 



