Nature Bulletin No. 242-A   October 29, 1966
Forest Preserve District of Cook County
Seymour Simon, President
Roland F. Eisenbeis, Supt. of Conservation

****:TRAFFIC TOLL OF WILDLIFE

The Jains, a religious sect in India, take a vow "not to kill". A Jain 
wears a cloth over his mouth for fear he might unknowingly swallow a 
gnat or a fly, and carries a broom to whisk small creatures from his 
path. We Americans go to the other extreme. We brush off the fact that, 
on our highways, we have carelessly killed and crippled more of our 
own people than two world wars. But that is not all. Highway traffic is a 
major cause of death to our wildlife.

Until the advent of the automobile, a few animals lost their lives on 
public roads. Occasionally a turtle or a snake was injured or crushed in 
the horse-and buggy days, but rarely a bird or mammal. The Model T 
Ford and its contemporaries, with an average speed of 25 miles per 
hour on the gravel and dirt roads of their time, ran down a few rabbits, 
possums, skunks and roving house cats blinded by their headlights, but 
there were few daytime casualties except sparrows, red-headed 
woodpeckers, and farmers' poultry.

Then, during the 1920' s, much of our present network of paved 
highways was built. In the late twenties, fast cars and trucks began to 
appear in numbers and, presently, most traffic was moving at 50 miles 
per hour, more or less. Then, a sharp upturn in the traffic kill of wildlife 
began, which continues to increase.

The first study of this traffic hazard was made by W. P. Flint of the 
Illinois Natural History Survey. He kept year-round records during 
1930, 1931 and 1932 of all wildlife and livestock killed on a 25-mile 
stretch of state highway between Urbana and Oakwood, Illinois. An 
average of one dead animal per day was found on each two miles of 
pavement. From April to October were the peak months. Of the total, 
almost half were English sparrows, approximately one-tenth were 
chickens, one-tenth were rabbits and one-tenth were gophers. Less than 
one-third were species useful to man: songbirds, domestic poultry, 
game animals and fur-bearers.

Another study of this toll of animals was made on Cook County 
highways in 1946 and 1 947 by forest preserve naturalists. A day-to-day 
tally of the casualties among the larger forms of animal life was kept for 
a total of 21,000 miles about equally divided between highways in rural 
regions, through suburban towns, and those traversing or bordering our 
forest preserves. For various reasons but principally on account of the 
large volume of fast traffic on the many 4-lane pavements, it was not 
possible to count small animals such as mice and songbirds, or even 
larger ones. Others were thrown off the pavement or, badly injured, 
crawled away to die. We may have seen only a fifth or possibly a half of 
the total.

Even so, here the picture is much different than in rural downstate 
Illinois. Rabbits were by far the most numerous, followed by squirrels, 
cats, possums and skunks -- in that order. On roads through suburban 
towns and rural regions, the percentage of cats killed increased sharply. 
Dogs, raccoons, gophers, groundhogs, mink, muskrats, a few weasels, 
and even one red fox, were the other large mammals counted. 
Pheasants, because of their size, were the most common birds found 
killed. Domestic poultry was uncommon. It was found that the annual 
kill by traffic of game and fur-bearing animals, on highways passing 
through or bordering our forest preserves -- a minimum of 3000 animals 
-- is about the same, per square mile of land, as the annual kill by 
hunters and trappers in downstate Illinois. To wildlife, the automobile is 
as deadly as the shotgun.