andomization of call-count routes 








The original call-count routes (established between 1951 and 1956, 
and hereafter designated "management routes") were, in many instances, 
selected in areas of high-density dove populations and were not repre- 
sentative of populations over entire States or management units. 
Randomly located routes were first employed in seven southeastern 
States in 1957 (Foote, Peters, and Finkner, 1958). A study of the 
random and management route data from these States confirmed earlier 
assumptions that a revision of the nationwide call-count survey routes 
should be undertaken if representative dove population indexes were to 
be obtained. This recommendation prompted the gradual selection and 
establishment of 912 randomly located call-count routes. In 1971, for 
the first time, data have been obtained from randomized routes in all 
48 conterminous States for 2 or more years. 
Both types of routes were run during the year of transition from 
management to random routes. This procedure permitted a direct com- 
parison of data (Foote, Peters, and Finkner, 1958). 
Physiographic stratification of call-count routes 
Biologists recognize the limitation of sampling wildlife popula- 
tions by political units. Census data collected and analyzed by eco- 
logical divisions represent better statistical design and could be 
expected to provide more precise information with the same effort. 
An ecological sampling design for the collection of dove popula- 
tion data, using physiographic regions as the basis for stratification, 
was suggested by Foote, Peters, and Finkner (1958). The 79 regions 
designated in this report (fig. 1) are based essentially on a map 
entitled "Physical Divisions of the United States" prepared by 
Fenneman (1931). The boundaries of these divisions were modified 
in several instances after examination of field data and more recent 
ecological studies. 

Breeding Density Index 
The Breeding Density Index (BDI) is an indicator of the number of 
doves per unit of area and is derived from the average number of calling 
doves per route. To obtain as accurate an average as possible for deri- 
vation of this index, the call-count data from each stratum in each 
ptate are weighted according to the land areas they represent. 
