10 BULJ.ETIN 1165, U. S. DEPARTMENT OF AGRICULTURE. 



of 126 pairs to the hundred acres. One tract of 40 acres, in 1918, 

 suffered the heaviest loss in the breeding population noted on a 

 single area. Several species found in 1917 were entirely absent the 

 following year, among them being the mockingbird and the brown 

 thrasher, each of which had been represented by two pairs, besides 

 several species of insectivorous birds. In 1917 there were three 

 species and four pairs of woodpeckers, and in 1918 not a woodpecker 

 was present. 



TENNESSEE. 



An average bird population of 107 pairs to the hundred acres was 

 found in Tennessee in 1917 on land that contained no woodland or 

 orchard and had 40 per cent in crops. 



LOUISIANA. 



Returns from Louisiana deal with land that was exceptionally 

 favorable to bird life, in the years 1916 to 1918, inclusive. A little 

 over 35 per cent of this area was in woods and more than 3 per cent 

 in orchard, while only 20 per cent was cultivated. The average bird 

 population for the three years was slightly over two pairs to the acre. 



RESULTS OF CENSUSES FROM WESTERN STATES. 



Reference to the map (Fig. 1, p. 7) will show that reports on bird 

 censuses from the western part of the country are very few indeed. 

 In this vast area stretching from the Plains to the Pacific physical 

 conditions are greatly diversified, and climatic conditions range from 

 humid on the eastern border through various degrees of aridity to the 

 humid region of the Pacific coast. Nothing more definite can be said 

 of the bird life of this area than that it is very variable. In all parts 

 of the country birds are inclined to concentrate in places where water 

 is available and trees and bushes offer shelter, and, judging from 

 present returns, this is especially true over the western part of the 

 country, particularly in the Plains region, where only a few species 

 nest on the open prairies. 



Beyond the Plains, in the Rocky Mountain region, is presented the 

 additional problem of altitude, and here there is also much heavy 

 forest, where birds are far from abundant, as the bird counts at hand 

 show. The valleys, when not cultivated, are frequently arid and fur- 

 nish nesting sites for few species of birds. 



The Great Basin, between the Rockies and the Sierras, offers many 

 interesting problems. Reclamation projects are bringing under 

 cultivation many thousands of acres of land formerly desert, and 

 changes in the bird life, both in species and in numbers, will result* 

 it is therefore very desirable that as many counts as possible be ob- 

 tained immediately from this region in order that material may be 

 at hand on which to base comparisons in the future. 



For the Plains region from North Dakota to Oklahoma data are 

 too few and scattered to allow any generalizations, except that birds 

 are seemingly less abundant than in the more humid regions farther 

 east, and also that they are very unevenly distributed. There are 

 few extensive tracts of woodland, the trees being largely confined to 

 planted groves and to strips along the river bottoms, and here, where 

 water and shelter are to be had, birds are sometimes enormously 

 abundant. 



