LINOIS BIRDS: Tyrannidae 
HIS IS THE FIFTH in a series of papers 
icicacd especially to bring together and 
mmarize the widely scattered and often almost 
ccessible published data on Illinois birds. The papers 
) include unpublished information gained from the 
hors’ continuing field studies, and information 
tributed by a number of excellent observers from 
eral areas of the state. 
Much of the quantitative data presented on migration 
| nesting represents special study areas (Fig. 1). Our 
icles On interpretation and presentation of data have 
n discussed in the earlier papers (Graber et al. 1970, 
1, 1972, 1973), each of which deals with a different 
uly of birds. Two points concerned with the 
sentation of data that were not considered in the 
lier papers deserve mention here. Unless otherwise 
ed, references to time of day are to central standard 
e. Also unless otherwise stated, measurements of wing 
3th refer to the wing chord, and measurements of bills 
r to the distance from the anterior edge of the nostril 
he tip of the bill. 
This paper deals with the flycatchers of Illinois, a 
up that presents some particularly difficult problems 
identification. Though the species are biologically 
inctive, some of them, especially species of the genus 
pidonax, are all but identical in appearance. Five 
pidonax flycatchers (yellow-bellied, Acadian, willow, 
tr, and least) occur regularly in Illinois, and there are 
unber of errors in the Illinois ornithological literature 
probably stem from misidentification of these and 
‘tr even less similar flycatchers. Except for the 
ow-bellied flycatcher, the Illinois Empidonax 
atchers are not identifiable in the field unless they 
or are associated with a nest and a_ particular 
itat. Even the yellow-belly can easily be confused 
| other Empzdonax, particularly in the fall (Mengel 
2), but because we have studied many collected 
imens of Empidonax flycatchers we believe we can 
ly identify the yellow-bellied flycatcher in the field if 
ee the bird at close range. Such field identifications 
tentative at best, however, and it is not easy to 
tify Empidonax flycatchers even when they are in 
1 (Phillips et al. 1966). 
n our censuses of the migration we counted 
singing (silent) Empidonax flycatchers, other than 
w-bellies, simply as unidentified Empidonax. 
ing birds or collected specimens were counted under 
‘ppropriate species, and even with yellow-bellies most 
ar identifications were based on songs or call notes. 
identified many more Empidonax in the spring than 
his paper is published by authority of the State of Illinois, IRS Ch. 127, Par. 
Itis a contribution from the Section of Wildlife Research of the Illinois Natural 
Survey. Dr. Richard R. Graber and Dr. Jean W. Graber are Wildlife Specialists 
/urvey. The late Miss Ethelyn Kirk served as Technical Assistant in the Section of 
¢ Research at the Survey. 
Richard R. Graber, Jean W. Graber, and Ethelyn L. Kirk 
in the fall, because birds sing more in the spring than in 
fall. Other methods of study, such as bird netting, are 
essential for this group particularly. In dealing with 
published records, we have generally accepted 
identifications of Empidonax flycatchers as given unless 
the record seemed clearly in error. Such errors are 
discussed briefly in the species accounts. Where 
problematical identifications were involved, we based our 
judgements, to the extent possible, on data from 
collected specimens.The available collections are 
woefully inadequate. 
Recently the American Ornithologists’ Union 
Committee on Classification and Nomenclature (1973) 
recognized the existence of two species of Traill’s 
flycatchers. The populations which for many years had 
been considered one species, Traill’s flycatcher 
(Emprdonax trailli), are now considered to comprise two 
distinct species — the willow flycatcher (E. trail) and 
the alder flycatcher (E. alnorum). The two forms differ 
slightly in song and nesting habits (Stein 1963), but are so 
similar in appearance that many specimens (in hand) 
cannot be specifically identified with certainty. Despite 
the extreme subtlety of the differences between the two 
forms, we have followed the A.O.U. Committee’s new 
nomenclature, where applicable, but have also used the 
old name (Traill’s flycatcher) in reference to the complex 
of populations when specific identification was not 
possible. 
For the flycatchers, as for other groups, vocalizations 
are interesting but also very difficult to treat ir writing. 
Consequently we have placed little emphasis on this 
aspect of Illinois ornithology. The phonetic interpre- 
tations of vocalizations which we and others use may be 
more misleading than helpful, as there are perhaps as 
many interpretations of a song or a call as there are 
interpreters. For example, we have never been able to 
hear the commonly used phonetic “fitz-bew” as the song 
of the willow flycatcher. To our ears there are definite 
“rrr” sounds in the song which the phrase “fitz-bew” 
simply does not convey. Audiograms of bird vocalizations 
are more precise, and unquestionably superior for 
technical studies of song, but they are probably of little or 
no more help than phonetics to students who have never 
heard the song or call. There is no real substitute for 
hearing and learning the song in the field. 
For help, particularly with the acquisition of data for 
this report on the flycatchers, we especially thank Mrs. 
William Carroll of Woodstock, James and Loraine Funk 
of Liberty, L. Barrie Hunt of Eastern Illinois University, 
Richard A. Anderson of St. Louis, Peter C. Petersen of 
Davenport, David Hayward of Carbondale, Lawrence G. 
Balch of Chicago, Mark Swan of Oregon, Michael D. 
Morrison of Sparta, Noel P. Lane of Edwardsville, 
William G. George of Southern Illinois University, 
