production into consideration. This limitation is especially 
noteworthy since a high percentage of an average fall popula¬ 
tion is composed of young-of-the-year. 
As a basis for breeding population indexes, it has been 
found that doves heard calling have provided a less variable 
index than doves seen. Recent studies (Frankel and Baskett, 
1961 and Jackson and Baskett, 196 ^) have shown that unmated 
males call at a greater rate than mated males. This suggests 
that the annual call-count census measures changes in the ratio 
of mated males to unmated males, rather than changes in breeding 
dove densities. However, Wight (in press) shows that changes 
in matedness, where the 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. Continued 
research on this problem is being conducted at this time. 
Weighting factors 
When combining data from several States to obtain breed¬ 
ing population indexes for management units or parts of manage¬ 
ment 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 combina¬ 
tion 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 1. 
Randomization of dove-call routes 
In order that the data on dove population density shall be 
representative of the breeding dove population of each State, 
random selection of dove census routes is desirable. The pre¬ 
sent management routes were, in some cases, selected in areas 
of high-density dove populations and do not yield representa¬ 
tive measurements of the breeding dove populations throughout 
the entire State. 
