Book News and Reviews 



137 



argue well for the accuracy of the observa- 

 tions on which they are based. 



One of the deductions drawn from the 

 data thus far obtained is "that the present 

 bird population is much less than it ought 

 to be, and much less than it would be if 

 birds were given proper protection and 

 encouragement. ..." The close agree- 

 ment between Mr. Burns' census of 

 1899-1901 and that of 1914 indicate that, 

 under normal conditions, or where birds 

 are neither especially encouraged nor 

 molested, the average summer popula- 

 tion is less than one pair to the acre. But 

 in the Bulletin under review we learn that, 

 where efforts are made to attract birds by 

 supplying them with nesting-places and 

 baths, their numbers may be increased 

 sevenfold. 



Thus at Chevy Chase, Md., no less than 

 148 pairs of 34 species of native birds were 

 found nesting on 23 acres. 



It is obvious, in the face of definite 

 statistics of this kind, how comparatively 

 useless are the vague terms by which we 

 have previously expressed the relative 

 abundance of species. But even these 

 terms of "common," "tolerably com- 

 mon," etc., are far more dependable than 

 statements based on casual observations 

 compared with hazy recollections. 



From an economic point of view, it is 

 of the first importance for us to have some 

 conception of the numbers of birds inhabit- 

 ing this country. We may study the 

 food-habits of a limited number of individ- 

 uals, but the economic relations of a 

 species at large can be estimated only 

 when we know approximately by how 

 many individuals the species in question 

 is represented. 



From a purely biologic aspect, it is 

 also of fundamental importance for us 

 to have some knowledge of our avian 

 population, as a basis on which to study 

 the relations existing between the bird 

 and its environments. 



Here, then, is an admirable opportunity 

 for the field student to cooperate with the 

 government, and, in closing this notice, 

 we take pleasure in appending a letter 

 from Mr. E. W. Nelson, Assistant Chief 



of the Biological Survey, in which he 

 calls for volunteer observers among 

 Bird-Lore's readers. We trust that they 

 will respond as cordially as they do to 

 the call for a Christmas Census. — 

 F. M. C. 



Mr. Nelson's Letter 



United States Department of .\griculture 



Bureau of Biology Survey 



Washington, D. C. 



February, 16, 1915. 

 Dr. Frank M. Chapm.^n, Editor "Bird-Lore:" 



Dear Mr. Chapman: A preliminary cen- 

 sus of the birds of the United States was 

 undertaken by the Bureau of Biological 

 Survey during the spring of 1914. The 

 results were so encouraging that the work 

 is to be repeated in the spring of 1915, on a 

 larger scale. Observers are particularly 

 desired in the West and South and, as 

 Bird-Lore has a wide circulation in these 

 sections, it is hoped that its readers will be 

 able to render valuable assistance in the 

 season's campaign. Anyone familiar with 

 the birds nesting in his neighborhood can 

 help, more particularly as only about the 

 equivalent of one day's work is needed. 



The general plan is to select an area con- 

 taining not less than 40 nor more than 80 

 acres that fairly represents the average 

 conditions of the district with reference to 

 the proportions of plowed-land, meadow- 

 land, and woods, and go over this selected 

 area early in the morning, during the 

 height of the nesting season, and count the 

 singing males, each male being considered 

 to represent a nesting pair. In the latitude 

 of Washington, D. C, the best time is the 

 last week in May; in the South the count- 

 ing should be done earlier; while in New 

 England and the northern part of the 

 Mississippi Valley, about June 10 is the 

 proper time. The morning count should 

 be supplemented by visits on other days, 

 to make sure that all the birds previously 

 noted are actually nesting within the 

 prescribed area and that no species has 

 been overlooked. 



Readers of Bird-Lore and others who 

 are willing to volunteer for this work are 

 requested to send their names and 

 addresses to the Biological Survey, Wash- 



