percentage changes have been applied to the base figure 
(average doves heard calling per route) to give an ad justed 
figure which shows the true relation of indexes from year to 
year. The selection of a base figure is necessary because 
not all routes are censused each year. 
Each year, beginning with @ base year, and on dove-call 
routes censused in 2 successive years, the average number of 
doves heard calling on each route in each State has been 
adjusted. This adjustment has been made according to the per- 
centage change from the previous year. For example, 1957 was 
selected as a base year in Alabama (table 2). In that. year, 
the average number of doves heard calling per route was 21.1. 
In 1958, the percentage change from 1957 in counts on com- 
parable routes was an increase of 12.8 percent, so the base 
figure of 21.1 was adjusted upward by 12.8 percent to a level 
of 23.8. In 1959, the percentage change from 1958 in counts 
on comparable routes was a decrease of 21.6 percent, or from 
23.8 to 18.7. 
TRENDS IN THE BREEDING POPULATION INDEX - 1963 
Eastern Management Unit 
The breeding population index for the Eastern Unit 
decreased 3.6 percent from the 1962 level (table 1). This 
marks the third year of decline since the peak index reached 
in 1960. Figure 2 shows that the breeding index of the 
Eastern Unit showed a general increase during the 7 years 
prior to 1961. The 1963 index is 9.7 percent below the peak 
1960 index and 2.6 percent below the Unit's 10-year average 
index (1953-62). 
The hunting States of the Eastern Unit showed a 7.2- 
percent decline from the 1962 breeding population index. The 
nonhunting States showed an 8.0-percent rise from the 1962 
population index level (table 1). 
Central Management Unit 
The breeding population index for the Central Unit decreased 
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