LINOIS BIRDS: Laniidae 
HIS PAPER ON THE SHRIKES of Illinois is 
the fourth in a series intended to summarize the 
uilable knowledge on birds of Illinois. The basic goals, 
cedures, and policies of the project were outlined in 
introduction to the first paper (Graber et al. 1970). 
the introductions to subsequent papers we have con- 
ered in more detail various problems in the interpreta- 
n and presentation of data on Illinois birds. 
Much of the information presented comes from the 
rature. Data from this source are so widely dispersed 
ough the thousands of papers published in the past 
tury that they are essentially lost to most students of 
Js. We estimate that our bibliography on Illinois birds 
nore than 85 percent complete. The literature avail- 
e to us is primarily that in the collective libraries of 
University of Illinois, including the Illinois Natural 
tory Survey Library, but we are also making use of 
library loans to fill in the gaps. The search for pub- 
ed reports continues, and we add worthwhile papers, 
h old and new, to the bibliography each year. For each 
ily account we try to have the literature coverage 
rent to the time our manuscript is submitted, i.e. usu- 
within a year of the date of publication. An inherent 
ger of a definitive project of this sort is that students 
be overly trusting of our coverage of the literature. 
urge all students who use the papers to weigh our 
mary of the literature against their own knowledge 
llinois birds and the pertinent literature. Corrections 
ny errors, whether of omission or commission, should 
er be published separately, or brought to our attention. 
For a number of species of birds, including the shrikes, 
only semblance of winter population data available 
Illinois are those from the National Audubon Society's 
ual Christmas counts which were started in 1900. We 
e used data from all of the Illinois census stations and 
e which touch Illinois or its natural boundaries (Fig. 
including data published in the (Illinois) Audubon 
tin and Iowa Bird Life. We have tried various kinds 
malyses on the Christmas count data, such as calcu- 
ns of frequency of occurrence by census, by year and 
lecade, and calculations of numbers of birds per cen- 
per hour of observation, and per mile traveled. 
The limitations in treatment of the Christmas count 
mation are dictated by the rough and incomplete 
we of the raw field data. In the case of shrikes, for 
nple, it can be shown that, on the average, more than 
hours of observation and 8,000 miles of travel have 
1 required for a party of observers to see a northern 
ke in central Illinois in winter. When we consider that 
‘his paper, in the biological notes series, is published in part with 
te funds. Dr. Richard R. Graber and Dr. Jean W. Graber are Wildlife 
alists in the Section of Wildlife Research of the Illinois Natural History 
y. The late Miss Ethelyn Kirk served as Technical Assistant in the 
m of Wildlife Research at the Survey. 
Richard R. Graber, Jean W. Graber, and Ethelyn L. Kirk 
the sum of all central Illinois counts, beginning in 1902, 
did not comprise 600 hours of observation time until the 
count was in its fourth decade, until about 1935, we can 
see the serious limitations of the count for studies of long- 
term population changes, particularly for relatively un- 
common species. No calculations, either of frequency of 
occurrence or population density, can have meaning based 
on such incomplete coverage. 
Besides their poor coverage, the early counts were 
also short on important collateral data, such as mileage 
traveled, habitats covered, and weather information. An- 
other drawback of the counts, pointed up particularly 
well by the shrike data, is the problem of inaccurate 
identifications. Our analysis (see under species account 
of the northern shrike) indicates that the two Illinois 
shrike species have sometimes been confused by students, 
though not necessarily more so on the Christmas counts 
than generally in winter. 
In important ways the counts have improved in re- 
cent decades — more complete coverage, more complete 
station data, and better informed participants in the 
counts. ‘hus, in presenting data from the Christmas 
counts we tend to emphasize the information for more 
recent decades, especially since 1940. In general, we have 
accepted species identifications as given except for in- 
stances where the data differ markedly from our personal 
observations. 
In our graphs on the occurrence of shrikes in the 
Christmas counts we have plotted data as the number 
of birds seen per 100 party hours of observation (a “party 
hour” can be defined as an hour of observation time by 
a group of observers, considered as a single observer). 
We used hours as the measure of censusing instead of 
miles traveled, despite the fact that mileage shows better 
correlation with numbers of shrikes seen (r = .617) than 
do the hour data (r = 415). We adopted this course 
only because some census takers still do not provide 
mileage data. 
It is a pleasure to acknowledge James and Loraine 
Funk of Liberty, Thomas May of Lenzburg, and Michael 
Morrison of Sparta for providing valuable information 
used in this report. Our colleagues William L. Anderson, 
Ronald Labisky, and James Seets of the Survey made 
particularly important contributions in the form of field 
data and specimens. We are also especially indebted to 
Milton W. Sanderson, of the Survey’s Faunistic Section, 
who patiently identified numerous fragments of insects 
from the stomachs of shrike specimens. John Unzicker 
and Wallace LaBerge identified spiders and Hymenoptera 
specimens for us, and James Appleby and George Godfrey 
identified the corn borer larvae. Staff members of the 
Survey’s Wildlife Research Office and Editorial Office 
provided characteristically fine help in the preparation 
