648 EXPERIMENT STATION EECORD. 



ECONOMIC ZOOLOGY— ENTOMOLOGY. 



Extermination of ground squirrels, gophers, and prairie dogs in North 

 Dakota, W. B. Bell and .S. E. I'ipkr (Xorth Dakota Hta. Circ. 4 (1915), pp. 11, 

 figs. 6). — It is estimated that the annual loss to farmers in North Dakota from 

 the depredations of six species of rodents amounts to more than a million 

 dolhirs, and in dry years this loss is probably more than doubled. The Richard- 

 son ground squirrel or flickertail, commonly called "gopher" in the State, is 

 the most conspicuous offender. 



In January, 1914, an investigation was started by the station in cooperation 

 with the Biological Survey of this Department, the field work commencing 

 early in April and continuing into September. It was found that the Richard- 

 son ground squirrel, like the California ground squirrel, is killed more readily 

 by strychnin absorbed through the cheek ix)uches from properly prepared 

 strychnin-coated grain than through the stomach, only one-fifth as much poison 

 being required to kill when thus taken directly into the circulation. The authors 

 give directions for the preparation of a formula which has given excellent re- 

 sults in exterminating the Richardson ground squirrel, and state that it is 

 equally as effective in destroying the Franklin or gray ground squirrel and 

 the striped or thir teen-lined ground squirrel. In tests made the average cost 

 of treating 1,528 burrows in 135 acres, including poison, grain, and labor, was 

 slightly over 2i cts. per acre. 



Methods of destroying prairie dogs and pocket gophers are also briefly de- 

 scribed. 



Preliminary census of birds of the United States, W. W. Cooke (U. S. 

 Dept. Agr. Bui. 187 (1915), pp. 11, fig. J).— This is a reix)rt of work carried on 

 during the summer of 1914 for the purpose of ascertaining approximately the 

 number and relative abundance of the different species of birds occurring in 

 this country. Such information has been found necessary in administering the 

 federal law relating to the protection of migratory game and insectivorous birds 

 as a basis for determining the adequacy of the protection now afforded them. 

 Nearly 200 reports were received from observers, mainly from the section of 

 the United States north of North Carolina and east of Kan.sas. 



" The census covered 58 of the 108 acres of the average farm of the North- 

 eastern States and revealed on this area a bird population of 69 nesting pairs, 

 and on the remaining 50 acres it is estimated that there would be about one 

 pair to the acre ; in all, 114 nesting pairs to the 108 acres of farmed land. On 

 the 46 acres of wild land existing for each 108 acres of farmed land it is safe 

 to assume that there would be fewer birds than on the census-covered area. 



" The results of the census show that the numbers of birds are too few. and 

 it is believed that with adequate protection and encouragement they can be 

 materially increased. The record for density comes from Chevy Chase. Md., 

 where 161 pairs of 34 species were found nesting on 23 acres. 



" This preliminary census shows that the most abundant bird on farms of the 

 Northeastern States is the robin; that the next is the English sparrow; and 

 that following these are the catbird, the brown thrasher, the house wren, the 

 kingbird, and the bluebii'd in the order named." 



Some common birds useful to the farmer, F. E. L. Beal (U. S. Dept. Agr., 

 Farmers' Bui. 680 (1915), pp. 27, figs. 28). — Brief popular accounts of the more 

 important birds of the farm, particularly as relates to their food habits. 



Food of the robins and bluebirds of the United States. F. E. L. Beal ( U. S. 

 Dept. Agr. Bui. 171 (1915), pp. 31, figs. 2). — This bulletin presents in detail the 

 results of investigations of the food of five species of American robins and blue- 



