rike population in Illinois, no firm data were collected 
itil the 1950’s. In 1957 Ronald F. Labisky of the Illinois 
atural History Survey made a record of the number of 
sting pairs of shrikes on the roadsides of a 36-square- 
le area of agricultural land near Sibley, Illinois (Ford 
dd McLean counties). In succeeding years we continued 
e survey and witnessed a steady decline of the shrike 
pulation until none were left in the area by 1966 (Fig. 
. Our extensive searches elsewhere between 1966 and 
72 revealed that what had happened to the shrike pop- 
ution in the Sibley area also happened over most of 
rthern and central Illinois. Furthermore, thé shrike 
pulation has declined in much of the Midwest ( May- 
id 1949, Petersen 1965, Erdman 1970). 
Was this near extirpation related to the decline of 
lgerows? In 1958 we measured the roadside hedgerows 
the 36-square-mile Sibley study area, and found 5.2 lin- 
“miles of hedge. With 10 pairs nesting in the area that 
w (Fig. 6), the density was 1.9 nests per mile of hedge. 
1959 the hedge declined to 4.8 linear miles, and the 
mber of nests to 8, or 1.7 per mile of hedge. We did 
measure the hedges of the study area again until 
2, when there were still 3.7 miles of roadside hedge 
no nesting shrikes. There were, in addition, at least 
miles of hedges in the area which were not along 
ds. In view of the quantity of hedge still left in the 
a, the disappearance of the shrikes would seem to 
uire some other explanation than just the reduction 
nedges. Another change which occurred in the Sibley 
a during the period when shrikes disappeared was a 
rked reduction in the acreage of hayfields (William 
Edwards and G. Blair Joselyn, personal communica- 
is). We have no data from which to evaluate the 
ct of this change on the shrike, but it may have been 
ortant, depending upon the value of hayfields as 
iging habitat for shrikes. 
In summary, there apparently were two levels of 
nge in the shrike population of northern and central 
Illinois —a relatively slow decline since about 1900, 
probably related to the removal of hedges in many areas, 
LOGGERHEAD SHRIKE 
BREEDING RECORDS 
NESTS OR YOUNG na ee foe 
JO Daviess Pe oi 2 
@ 1950 — en ar é 
v, mest ay \ 
A 1900-1949 e~ 
wHiTesige~[ ‘A € 
M BEFORE 1900 ieik Sey 
Se) ee | an @ | 
PAIRS OR SINGING EO: mo Fubna 
MALES (MAY-JUNE) |.) rye ie 3 eM 
| wannen | Hes a RR] LivinGston | a : 
O 1950— Oo ¥-- Seas | a 
af >. =f =— e 
Imc@QJouch) Aron _/ Orazewere Mec MORN ®&. L.——— —— 
A 1900 - 1949 {en Me uae: re 
oO Pi eee oe hee 
1 -@ Ma) | Ail 1 
C) BEFORE 1900 
eee Sie 
J fF, 
oO ( ae ape | ANCRMON ie) 
PIKE \scorry \ co 
\ LO B} g 
aes. wi Qe i le 
JERSEY 
LL mi 7 een ; vocal A a) ach wae | 
OEE cass | “or a % ; | ; 
Largely Extirpated 
North of Line 
by 1965 
e+ = ETT 
MADISON 
f—-—-- #4 
¢ —— } = 
ey Sy res 
prot) renny\ 5 | * 
fa 
1 
FROMM IN 
i DRE 2 
; oe Se 
wu te} 
a 
iN 
P 
10. O_19 20. 49 SD 
a ee ee ee 
Fig. 5. — Breeding records for the loggerhead shrike in IIli- 
nois. Singing male records are for May and June only. 
Fig. 4. — (To left and below.) Egg laying and migration seasons of the loggerhead shrike in Illinois. Spring and fall graph lines 
v the highest daily count of each 3 days (left scale) in southern Illinois, 1967 and 1970. Asterisks represent counts made either 
ther years or by other observers. Shaded areas show the percent of eggs laid on a given date (right scale). 
20 
SOUTH 
AUG SEP OCT 
NOV 
