/ 
index to the breeding population but does not take production 
into consideration. This factor is especially significant 
since a high percentage of the fall population is normally 
composed of young-of-the-year. 
Recent studies (Frankel and Baskett, 1961; Jackson and 
Baskett, 1964) have shown that unmated males call at a greater 
rate than mated males. This suggests that the reliability of 
the annual call-count census is reduced by the variability in 
the ratios of mated males to unmated males. However, Wight 
(1964) shows that changes in the ratio of mated to unmated 
males, where sex ratios of the adult segment of the population 
approach equality, will not significantly alter the capability 
of the dove call-count census to measure annual trends in the 
mourning dove breeding population. Irby (1964) also states 
that he found no evidence on his study areas in Arizona that 
the number of unmated males could materially affect call-count 
figures. 
Weighting factors 
When combining the data from several States to obtain 
breeding population indexes for management units, or, parts of 
management units, it is necessary to give appropriate weight 
to the data from each State. This is done by multiplying the 
adjusted average number of doves heard calling per route in 
each State by the estimated area of dove habitat (in square 
miles) in the State to obtain a breeding population index value. 
These index values from each State are then added together to 
obtain the properly weighted breeding population index for the 
combination of States. This weighting procedure recognizes 
differences between States, both in dove density and in the 
amount of habitat. Dove habitat area was estimated and listed 
in the 1958 Mourning Dove Newsletter in table 5 and management 
units were described by Kiel (1959) in Special Scientific 
Report--Wildlife No. 42. 
Randomization of dove call-count routes 
In order that the data on dove population density shall 
be representative of the breeding dove population of each State, 
random location of dove census routes is desirable. The original 
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