20 19 
10 20 30 9 19 29 9 
MAR APR 
HM 
CENTRAL 
20 20 19 
19 20 30 10 20 30 9 19 
MAY SEP OCT NOV 
ig- 18.—Migration seasons of the hermit thrush in different areas of the state (see Fig. 1). Spring and fall graph lines (1967-1970) show the highest 
ount of each 2 days. Star symbols represent counts made in other years or by other observers. Dot symbols represent counts made in west-central I]- 
lines without dots represent the east. Dashed graph line (north) represents the cumulative counts of birds made by Benjamin T. Gault between 
nd 1927 mainly in Du Page County, and shows the long-term peaks and range of migration dates. 
und one to two hermit thrushes per 100 acres in forest 
hrub areas. The Christmas counts also show great 
l variation in the hermit thrush population (Fig. 21). 
ne years more hermits have been found in northern 
is than in the southern region, but such records were 
bly more a reflection on the distribution of observers 
listribution of the birds. Cooke (1885) reported high 
’ populations (5-20 hermits seen per day) in thickets 
the Mississippi River, but no recent observer has rec- 
comparable numbers. In a 3-day census at Grafton, 
1940) found only two hermit thrushes. Bartel (1954) 
ed three in a day near Lisle (January 17, 1954), ina 
hen the Christmas counts indicated high populations 
south (Fig. 21). 
itler (1896) suggested that hermit thrushes suffer the 
ype of cold mortality in the winter and spring that is 
able in bluebird populations, and James’ (1961) stu- 
dies support this view. The low populations in 1958, 1959, 
and 1960 probably refllect such mortality. 
Food Habits 
In his studies, Forbes (1903) examined 21 specimens of 
hermit thrushes, which were nearly all taken in the spring 
in northeastern Illinois. Even for a thrush, the amount of 
insects eaten by hermits was high (84 percent of all food). 
Coleoptera (29-30 percent) were of major importance, es- 
pecially predaceous ground beetles. Forbes noted that the 
spring migration of the hermit thrush is timed with the 
emergence of many beetles. Gault (1884-1889, unpub- 
lished notes) also found beetles to be the principal food. 
Lepidoptera (18-19 percent), and ants (13-15 percent) 
formed much of the rest of the diet. Like the wood thrush, 
hermits ate more millipeds (12 percent) than most birds. 
21 
