lyzed to determine population trends for the years 1903- 
1955. 
2.—Even though most of northern and central [llinois 
offered fairly uniform habitat of cultivated farm land 
with relatively little forest, the distribution of raptors 
was not uniform, and raptor populations varied consid- 
erably even within relatively small areas. Highest con- 
centrations of raptors were in the southern part of the 
state. Through the years a given locality, in relation 
to other localities, has tended to show a consistent 
rank with regard to the density of its raptor populations, 
as reported in the Christmas counts. 
3.—Analysis of frequency of occurrence for all spe- 
cies of raptors recorded on Christmas counts in the 
period 1903-1955 was based on 527 censuses—103 in 
southern, 123 in central, and 301 in northern [llinois. 
This analysis shows the expected higher frequency of 
prairie-inhabiting species of raptors in central and north- 
ern Illinois and of woodland species in southern [Ili- 
nois. Regardless of habitat, certain species, such as 
the sparrow hawk and the marsh hawk, were seen with 
increasing frequency from north to south, as though re- 
sponsive to the temperature cline. 
4.-The combined data for all raptor species show 
that there has been a marked and consistent decline in 
winter raptor populations during the period 1903-1955. 
Peaks representing years of high population are lower 
in later years. Trends in raptor populations were de- 
duced from birds per observer-hour, birds per party-hour, 
and birds per mile. 
5.—The records of individual species show that the 
rough-legged hawk has suffered the severest decline in 
numbers; the red-tailed hawk, the sparrow hawk, and 
the barred owl also have decreased. Marsh hawk and 
red-shouldered hawk populations have not changed ap- 
preciably. The bald eagle has been increasing in num- 
bers since the early 1940’s, but this is the only species 
for which a notable increase was shown. The records 
for many species are too incomplete to evaluate. 
6.—Because the decline in raptor populations is 
shown particularly among the less wary species and 
those species that are most likely to be encountered by 
man, it is suggested that man may be directly responsible 
for the decline. This view is corroborated by the fact that 
many raptor band returns are from birds that were trap- 
ped or shot and also by the indication that a notably 
lethargic species, the rough-legged hawk, has suffered 
the severest population decline. 
7.-The species of raptors—Buteo spp., Circus spp., 
and Falco sparverius—that have been protected by law 
since 1919 were seen at least seven times as frequently 
on Illinois Christmas counts as the previously unpro- 
tected accipiters and the great horned owl. 
8.—-A briefly annotated list summarizes the winter 
records of the species of raptors reported from [Illinois 
on Christmas counts in the period 1903-1955. 
LITERATURE CITED 
Broley, Charles L. 
1947. Migration and nesting of Florida bald eagles. Wilson Bul. 59(1):3-20. 
Chapman, Frank M., Editor 
1900. A Christmas bird-census. Bird-Lore 2(6):192. 
Cooke, May Thacher 
1941. Returns from banded birds; Recoveries of some banded birds of prey. Bird-Banding 12(4):150-60. 
Kifrig, C. W. G. 
1939. Save the hawks! [1]. Audubon Soc. Bul. 1939(30):5-11. 
Hickey, Joseph J. 
1955. Letter to the editor. Wilson Bul. 67(2):144-5. 
King, D. B., and R. K. Winters 
1952. Forest resources and industries of Illinois. Ill. Ag. Exp. Sta. Bul. 562. 95 pp. 
Lincoln, Frederick C. 
1936. Recoveries of banded birds of prey. Bird-Banding 7(1):38-45. 
Nice, Margaret M. 
1945. Rare and endangered species of birds in northern Illinois. Il]. Audubon Soc. Bul. 1945(53):9-10. 
Smith, Harry R., and Paul W. Parmalee 
1955. A distributional check list of the birds of Illinois. Ill. Mus. Pop. Sci. Ser. 4. 62 pp. 
Stewart, Paul A. 
1954. The value of the Christmas bird counts. Wilson Bul. 66(3): 184-95. 
Wallace, George J. 
1955. An introduction to ornithology. Macmillan Company, New York. 443 pp. 
24 <s" 
