Distribution 
The general distribution of the robin is shown in Fig. 3. 
Robins surely nest in every township in the State, but as yet 
the literature does not accurately reveal the distribution 
(Fig). 
ROBIN 
BREEDING RECORDS 
NESTS OR YOUNG 
@ 1950 — 
A 1900-1950 
@ BEFORE 1900 
PAIRS OR SINGING 
MALES (JUNE) 
O 1950 — 
O BEFORE 1900 
O 
Scale 
2039 40 SOMiles 
o_O 10 
Fig. 5.—Breeding records for the robin in Illinois. Singing male rec- 
ords are for June only. 
Nesting Habitats and Populations 
The earliest references to the robin in Illinois comment 
on its domestic nature (Kennicott 1853-1854), and its 
affinity for human residential areas as nesting habitat has 
probably increased (Table 1). Ford (1919) noted that while 
many species disappeared as the city of Chicago developed, 
the robin remained. Carpenter (1935) believed that the 
robin had a major influence on the forest edge community 
at all seasons but winter. Gates’ (1911) classification of the 
robin as a dominant species of mixed forest and of secon- 
dary abundance in hedges and orchards is surprising, and 
the available census data do not bear him out (Table 1). 
However, there are no census figures available for any 
sandy-soil areas in the state. A difference in nesting ha 
tats is apparent between northern and southern TIilir’ 
(Table 1). There is relatively less use of nonurban habit 
in the south, where nearly 80 percent of the nesting popt 
tion is found in towns, versus 60-70 percent in central ; 
northern Illinois. 
Information on nest-site location in northern and ¢ 
tral Illinois is summarized in Table 2. The list of pli: 
used is undoubtedly very incomplete. Klimstra & Stieg 
(1957) provided data on nest sites in Carbondale, Ilir 
There are no studies that relate plant use to plant avail 
ity. 
: The recorded heights of robin nests vary from | ton 
than 50 feet above ground. The literature indicates mi 
of nest heights in northern Hlinois around 4-6 feet, I( 
feet, and 20-25 feet, and average heights of about 7 fee 
rural nests and 10 feet for urban nests. In both places 
height tends to increase by as much as 3-4 feet as the se: 
passes. The average height of 73 nests in central Illi 
was 10 feet, and early-season nests at Carbondale aver: 
about 15 feet (Klimstra & Stieglitz 1957). 
We have found no data on territory size for the rob 
any habitat. 
Nesting Cycle 
Singing has been recorded in Illinois from late Jan 
(south) and February (central) to November (Sill 
1899 and 1902, Ridgway 1915, and Musselman 1939) 
rarely at night (Musselman 19305 
For populations in northern Illinois at least, the |! 
ing records show that robins have a strong tendency 
turn as breeding birds to the vicinity of their birth (F 
1945). Published banding data are lacking for souther 
nois, but Ridgway (1925) recorded a club-footed robu 
returned to nest each year at Olney. 
The nesting season (onset of nest building to fledg 
last young for the population) lasts from about March 
September 2 with surprisingly little difference ap} 
between south and north. Single nesting cycles for a | 
robins required 36-37 days in the north (Charles 190 
Leach 1927). Time requirements for different phases 
cycle have been recorded as follows: 3-10 days fo 
building (Charles 1909, Scherer 1924, Klimstra & St 
1957, and Davis 1969), 11-13 days for incubation (C 
1909, Scherer 1924, Leach, 1927, Labisky 1966, and 
1969), and 13-15 days for nestling life (Charles. 
Scherer 1924, and Leach 1927). 
Maximum egg production occurs between mic 
and mid-May in central and northern Illinois (Fig. ‘ 
data on the hatching peak presented by Klimstra ¢ 
glitz (1957) indicate a similar curve for the south. 
are no adequate data on clutch size for southern | 
but in a sample of 188 nests found in northern and ) 
Illinois we see little regional variation. Clutches of : 
seven eggs are rare, representing less than 1 percer 
sets. Five-egg clutches are uncommon, representi 
percent of the sets (see also Blocher 1933, and Hess 
