cidedly later fall migration for the species. Just how 
e Traill’s flycatchers may be found on their nesting 
ritories has not been determined, but considering 
ing dates as late as July 27 (Fig. 34) we might expect 
at at least a few Illinois birds would still be occupied 
th nesting until about September 1. In Wisconsin 
Cabe (1951) found that regular singing by Traill’s 
catchers ended August 9-11. We have heard the 
aill’s flycatcher song (species ?) but once in September, 
the 5th at Urbana, Illinois. 
At least 15 specimens of Traill’s flycatchers have been 
‘ked up, with other nocturnal migrants, at television 
vers in central and northern Illinois on dates between 
gust 31 (INHS specimen), and October 7 (Petersen 
59). We have examined 12 of these specimens, and all 
t one appeared to be alder flycatchers. This is in 
~ping with our general impression that in tower kills 
rthern forms tend to be more prevalent than southern 
ms. On one night, September 1-2, 1972, at least 5 
ers, all immatures, were killed at towers in central 
nois. A kill on the night of September 20-21, 1966, 
duced two immature alders and one adult willow 
catcher. 
We do not know if there is a difference in the timing 
the fall migration of the two species. For the Traill’s 
nplex, the peak of the fall migration probably occurs 
ate August and early September, or possibly even later 
g. 34). The northern Illinois specimen of October 7 is 
latest Illinois record of which we know. 
Both adult and immature specimens taken in 
stember show only very few pin feathers in the body 
mage, most notably the throat, suggesting that the 
It may be largely finished in August. One adult male, 
en August 31, was in worn plumage however, with no 
It in evidence. We could not certainly identify the bird 
(0 species. 
\d Habits 
Two specimens of Traill’s flycatchers examined by 
bes (18826) had eaten insects exclusively, one fourth 
ag canker worms, and one-third Ichneumons. 
other one-fourth of the stomach contents was beetles, 
| about one-tenth was ants and other Hymenoptera. 
\ST FLYCATCHER (Empidonax minimus) 
(Fig. 37 and 38) 
ing Migration 
The earliest recorded arrival dates of least flycatchers 
llinois, April 11 for southern Illinois (Fig. 39) and 
il 12 for the north (Walter & Walter 1904), are 
dably exceptional, and the alleged arrival date of 
‘ch 30 for the north (Abbott et al. 1933) is probably 
*tror. Usually least flycatchers are not found in the 
> until late April or early May, with peak numbers 
iring April 28-May 10 in the south, May 7-16 in 
ral Illinois, and after May 10 in the north (Fig. 39). 
‘Migration in central and northern Illinois extends 
June, and in the north a relatively small number 
remain to nest (Fig. 39). The species has also been 
recorded in the St. Louis area as late as June 3 (Widmann 
1907). 
Distribution 
The least flycatcher is a nesting species of the 
northern United States and Canada. It winters in Mexico 
and Central America (Fig. 38). In Illinois the species may 
nest as far south as Marshall County where Barnes found 
a nest in 1910 (Illinois State Museum specimen) and 
Iroquois County where we have found singing territorial 
males in recent years (Fig. 40). There are no authentic 
records of nests in central Illinois. The listing of this 
species as a breeding bird in Hancock County (American 
Ornithologists’ Union 1957, George 1971) is apparently 
based on the fact that Worthen collected it at Warsaw 
during the “breeding season” (Widmann 1907). The 
McLean County record (American Ornithologists’ Union 
1957) and a Clinton County record (Anonymous tor) 
lack substantiation. The listings of the species in the 
breeding bird census at Decatur (Chaniot & Kirby 1955) 
and in “summer census” at Urbana (Wandell 1948) are 
Fig. 37. — Empidonax species. This small flycatcher is 
representative of the genus, species of which are best identified in the 
field by their song. 
43 
