MOCKINGBIRD (Mimus polyglottos) 
(Fig. 5) 
jpring Migration 
The Illinois literature is almost devoid of direct refer- 
suces to migrations of the mockingbird. The only clue 
ivailable as to the nature of the migration was provided 
yy a specimen killed with a group of night migrants at a 
elevision tower in Champaign County May 7, 1956 
Brewer & Ellis 1958). As indirect evidence of the mock- 
ngbird’s migration there are the many records of mock- 
rs appearing in northern Illinois in late April (especially 
fter April 17) and May (Clark & Nice 1950, Coursen 
947, Ford 1956, and others). 
The spring migration is somewhat obscured by the 
iresence of mockingbirds in winter in many parts of the 
tate, but even in southern Illinois our censuses showed 
ae mockingbird population fluctuating seasonally in a 
attern that suggested migration (Fig. 2). Both in south- 
rn and central Illinois the highest spring counts were in 
.pril. ‘The distribution of sightings of mockingbirds re- 
orted in the literature for northern Illinois and our cen- 
is data for the central and south indicate a timetable for 
1e mocker similar to that of the brown thrasher. 
CENTRAL 
NW 
12524 l2 24 12 24 12 24 
t 40 MARCH APRIL MAY JUNE 
( 
) 35 
j SOUTH 
- 30 
; — NUMBER OF BIRDS 
) 
) Feo 
] 
15 
Te) y 
5 \ 
fe) EGG LAYING 
12 24 12 24 12 24 12 24 12 24 
FEBRUARY MARCH APRIL MAY JUNE 
Fig. 2. — Nesting and migration seasons of the mockingbird in different regions of the state (see Fig. IVF 
NUMBER OF BIRDS 
° 
NESTING 
Distribution 
The general distribution of the mockingbird is shown 
in Fig. 3. In recent years mockers have been reported in 
winter throughout much of the breeding range, and with 
increasing frequency, even north of the main breeding 
range (Andrews 1967). There are recent nesting records 
in the northern tier of Illinois counties but there are still 
no published nesting records for most of the counties, even 
in southern Illinois (Fig. 4). At least as early as 1933 
a mockingbird nest was reported north of the Illinois line 
in Wisconsin (Van Sickle 1942), yet even today the mock- 
ingbird population is sparse north of the central zone. 
Ridgway (1889) and Ferry (1907) pointed out that the 
distribution of the mocker was irregular. Population 
densities of mockingbirds are still highly variable from 
place to place. For example, mocker populations are 
notably higher in southeastern Illinois than in the south- 
west. 
Even before the turn of the century, it was recognized 
that the mockingbird was extending its Illinois range 
northward (Forbes 1880). A number of observers have 
provided important reference points on the progression 
of the range extension (Fig. 4). Silloway (1902) found 
mockingbirds nesting only “sparingly” in northern Ma- 
rae 
12 24 12 24 12 24 12 24 
JULY AUGUST SEPTEMBER OCTOBER 
WW 
ke 
aq 
ey 
z 
WW 
> 
o 
40 2 
oO 
(a) 
oNESTING Me < 
20 
Oo 
ty 
Om 
(e) 
aa O Ad 
12 24 12 24 2 eye 12 24 12 24 
JULY AUGUST SEPTEMBER OCTOBER NOVEMBER 
Spring and fall graph 
les show the highest daily counts of each 3 days (left hand scale). The lines are interrupted where data have not been col- 
sted. Shaded block indicates length of the nesting season and level of adult nesting population. Egg-laying graph line (right 
nd scale) is based on repeated searches of roadside habitat throughout the nesting season. 
