ioe AUD OU BeOCNe BU LL Bete N 7 
Cooperative Study of Migration — 1955 
By JAMES H. ZIMMERMAN 
IN 1952 WE DREAMED of plotting on maps the arrival dates of certain com- 
mon migrants in every county of the 41 states and provinces east of the 
Rockies, from the Gulf into Canada, for 6 years. Our aim was to study, in 
unprecedented detail, the effects of our rapidly changing weather on the 
timing, extent, speed and direction of bird flights. Only with the recent 
gratifying growth of Audubon and other nature clubs all over the country 
has there been a sufficient number of birders scattered across our vast fly- 
ways to make possible the tracing of migrants almost from town to town. 
Heretofore, we have known only the general outlines of migratory flights. 
The average progress of many birds was mapped long ago from arrival 
dates at scattered stations, perhaps one or two per state. Many studies have 
more recently revealed that birds arrive or leave during certain types of 
weather. Sometimes it seems to be warm temperatures, south winds, or 
storms, that favor flights northward in spring; the picture in fall is less 
clear. Intensive observations are needed, but they must cover large enough 
areas to encompass whole weather patterns. 
Now in its third year, this study promises to fulfill our ambitious dreams. 
The hundreds of reports have demonstrated everyone’s willingness to share 
notes. Once on IBM punch cards, the arrival dates are easily sorted and 
totalled. They are available to bird students, some of whom are already 
relying on them in their own research. We have so far concentrated on find- 
ing more observers. A preliminary check of the reports received (see 
Audubon Magazine, May-June, 1954, pp. 180-133) tantalizingly showed that, 
in 1953, there were already enough cooperators to provide very interesting 
results, but not yet enough to remove our findings from the shadow of 
doubt. In 1954, the response happily was three times as great, thanks to 
more publicity. If this trebles again in 1955, we shall be able to see for 
certain whether, indeed, white-throats and swifts, for instance, do move 
north only on certain dates as much as a week apart, and whether they do 
jump such long distances as they seemed to when data were meager. So in 
our last drive for more cooperators everywhere, this year, before we de- 
vote our attention mainly to study of the accumulated results and the new 
reports, we seek many additional observers, not only in the poorly-repre- 
sented parts of Illinois, but even in the Chicago area, which has provided 
a large share of Illinois reports in the past. There just aren’t enough orni- 
thologists, including bird-banders, to go around; hence we must depend on 
every backyard bird-watcher as well. One observer in each neighborhood 
isn’t enough. Is your town and your bird club well represented on our maps? 
How to make and report observations: Our ideal cooperator doesn’t make 
special trips to find all species listed. Rather, he spends a few minutes 
nearly every day in the same area, such as his own yard or on the way to 
work. (Observations on occasional visits to other areas should be reported 
separately.) He reports only those species he is sure he can identify. For 
species that winter nearby, he reports on migrants only when they can be 
distinguished from the resident individuals. He reports his own first dates, 
