Fig. 4. — Egg-laying and migration seasons of the eastern kingbird 
ifferent areas of the state (see Fig. 1). Spring and fall graph lines 
)7-1970) show highest daily count of each 2 days (left scale). Asterisk 
bols represent counts made in other years or by other observers. 
ded areas show the span of dates during which egg laying has been 
rded. 
40 NORTH 
20 
10 . 
3) 
we 
ey Le) 9 I9 29 9 19 
AUG SEP OCT 
20. 30 9 [Saeco ) I9 
20 
fe) %, 
) 
%*%X * 
ee) 9 Sic 9 19 
AUG SEP OCT 
EASTERN KINGBIRD 
BREEDING RECORDS 
NESTS OR YOUNG 
@ 1950 — 
A 1900-1949 
@ BEFORE 1900 
PAIRS OR SINGING 
MALES (JUNE) 
O 1950 — 
A\ 1900 — 1949 
C) BEFORE 1900 
Fig. 5. — Breeding records for the eastern kingbird in Illinois. 
Singing male records cover the period June 1 to early July. 
in Olney, but we know of no significant recent 
populations in urban habitat. Eiseman & Shank (1962) 
witnessed a nesting attempt by kingbirds in Chicago that 
was aborted apparently because of the commotion of 
human traffic. 
From the statewide censuses of birds, we concluded 
that the state population of eastern kingbirds declined 
about 50 percent between 1907 and 1957, and that the 
loss was particularly great in southern Illinois (Graber & 
Graber 1963). We attributed the decline to large acreage 
losses of two important kingbird habitats — pastures and 
orchards. Eifrig (1937) also believed the kingbird 
population was declining, but attributed the change to 
reduced fly populations. 
No territories of kingbirds have been measured in 
Illinois. The species is renowned for its aggressive 
behavior toward some other birds, including species of 
hawks, crows (Corvus brachyrhynchos), nighthawks 
(Chordeiles minor), red-winged blackbirds (Agelaius 
phoeniceus), and others (Ridgway 1889, Hankinson 
1915, Musselman 1933, Back 1934-35). It is also 
surprisingly tolerant of some other species. The orchard 
oriole (Icterus spurius) sometimes nests in the same tree 
with the eastern kingbird in southern Illinois. There are 
7 
