





























Status of the Central Management Unit population 
1971 populatton dtstrtbutton.==Highest population densities in 
fhe Central Management Unit were distributed in the eastern and central 
sections, especially in the Great Plains and Central Lowlands. Low 
jensities were rather-uniformly distributed in the western and south- 
western sections of the Unit (fig. 4). States represented by a mean 
of 30 or more doves heard per route included Kansas, Nebraska, and 
South Dakota (table 3, fig. 3). Kansas had the highest mean BDI of 
any State, with an adjusted mean of 58.9 doves heard calling per route. 
1970 to 1971 population changes.--The Central Unit BDI declined 4.1 
percent from 21.9 doves heard per route in 1970 to 21.0 doves heard per 
route in 1971 (table 3). The 1971 population levels were substantially 
higher than in 1970 over much of the northern and northeastern sections 
of the Unit, and generally lower throughout the central and southcentral 
areas (figs. 5, 6). From 1970 to 1971, the combined hunting States 
index decreased 5.2 percent, and the combined nonhunting States index 
declined 1.8 percent (table 3). 
In 1971, the mean temperature at the start of the surveys was 
Significantly colder than in 1970: Central Unit, - 3.3 degrees Fahren- 
heit; hunting States, - 3.0 degrees; and nonhunting States, - 3.9 
degrees (table 2). The mean survey date in 1971 was one day earlier 
than in 1970. A slightly greater proportion of the 1971 routes were 
under conditions of high disturbance. 
1961 to 1971 long-term population trends.--In 1971, the Central 
Unit BDI declined for the fifth successive year to the lowest level for 
the ll-year period (table 3, fig. 7). The population index also declined 
for the fifth successive year in the combined nonhunting States, while 
the population level for the hunting States has declined three times 
during the last 5 years. Both the combined hunting States and the com- 
bined nonhunting States indexes are at their lowest levels for the period 
(table 3, fig. 12). Current population levels are well below the pre- 
ceding 10-year means: Central Unit, -14.9 percent; combined hunting 
States, -8.5 percent; and combined nonhunting States, -26.5 percent 
Pigs. 7, 12). 
Regression analysis shows that a significant downward trend in the 
dove population index occurred from 1961 to 1971 in the Central Unit. 
Similar downward trends were observed for the combined hunting States 
and the combined nonhunting States (table 3, fig. 9). The annual rates 
of decline in the adjusted BDI's were determined as follows: Central 
Unit, -2.5 percent; combined hunting States, -1.3 percent; and combined 
Nonhunting, -4.7 percent. Significant upward population trends occurred 
in Arkansas, Colorado, and Nebraska; downward trends were evident in all 
but three of the remaining States (table 3, fig. 10). 
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