die tees nue. Us BeOoNe Bb! Ur UetlaheT TN 5 
species (that highest total is in parenthesis). Again, 51 different counties 
were responsible for reporting the highest individual total for one or more 
species. Table 4 gives the 16 counties which reported the high counts for 
7 or more species. 
The five most common remained the same as in 1972, with the 
Common Grackle, 38,000+, the most abundant. The Mourning Dove 
moved from tenth to sixth place, while the order of the following six 
species remained unchanged. For comparison of these results, see Table 5. 
An important function of this bird count is to measure populations. 
In order to acquire meaningful results, comparable data must be obtained. 
Such measurements are generally based on the number of party hours of 
observation; therefore, it is important for all observers and especially 
compilers to be able to accurately compute party hours of observation. 
If party hours are computed properly, it is possible to determine popula- 
tion changes of species over a period of years, to compare existing popula- 
tions in different parts of the state, etc. 
In order to show the status of various permanent residents, summer 
residents, and migrants at different latitudes in Illinois, I have divided 
Illinois in four areas. Table 6 shows the number of counties and party 
hours for each area. The actual counties in each area are shown graphic- 
ally in Figure I and are listed in Table 7. Figure 2 shows the relative 
abundance of selected species per ten party hours (approximately equal 
to one day of observation) for the four latitudinal divisions. The num- 
ber in parenthesis following the species name is the statewide average 
number of birds per ten-party-hours. 
1t each species was compared for each area on such a figure, the 
statewide relative abundance and distribution for those species could be 
observed. For permanent residents such as the Red-bellied Woodpecker, 
Mockingbird, Carolina Wren, Cardinal, etc., any day could be used for 
the count; for summer residents (Purple Martin, Baltimore Oriole, etc.) 
the count day must occur after the birds had returned to their breeding 
area; for migrants, the count day selected would show how far and in 
what abundance the species had moved through the state. 
Such migrants as the winter residents and early spring species 
(Yellow-bellied Sapsucker, Palin Warbler, etc.) would be most common 
in the northern part of Illinois while the late spring species (7 ennessee 
Warbler, and, this year, some summer residents like the /ndigo Bunting, 
Red-eyed Vireo, Yellowthroat, etc.) would be most common in the 
southern part of the state. From the figures, readers can see that Red- 
tailed Hawks, Loggerhead Shrikes, Red-belhed Woodpeckers, Eastern 
Bluebirds, Carolina Wrens and Cardinals were most common in southern 
Illinois; Red-headed Woodpeckers and Horned Larks were most common 
in central Illinois; and the Belted Kingfisher and Purple Martins were 
about equally common throughout the state on 5 May 1973. 
Most observers and compilers submitted all necessary information 
concerning the count. The County statistics appear in Table 7 (Col. 2 
lists the area of the state the county occurs in; Col. 4, the total number 
