Nature Bulletin No. 81   August 31, 1946
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Superintendent of Conservation

****:RATS

Rats and men have been at war since the dawn of history. The "cradle 
of mankind" Central Asia, apparently was also the place of origin of the 
rat. From there, living and traveling with man, it has spread over the 
globe. In the United States today there are about as many rats as there 
are people.

Cur common rat is the Norway or brown rat which arrived here from 
Europe before the Revolutionary War. Fiercer and more cunning, it 
soon exterminated the black rat and the roof rat which had migrated 
here with the early colonists and thrived. The black rat -- which is 
glossy black above, smaller and more slender -- and the roof rat, a close 
relative, are found now only rarely in some of the southern states, 
although still common in tropical America.

These three rats and the common house mouse, another immigrant, are 
distinguished from our native rats and mice by having three rows of 
tubercles along the crowns of their molar teeth. Cur principal native rats 
are the rice rat, the cotton rat, and that friendly nuisance: the wood rat 
or pack rat.

The Norway rat is the most destructive animal in the world. In the 
United States, each year, they consume and damage foodstuffs and 
property valued at hundreds of millions of dollars. Infested with fleas, 
and commonly living in cellars, refuse dumps and filth, they transmit 
many serious human diseases, including typhus and bubonic plague. 
They are hated, loathed and feared. They possess acute senses, 
particularly the sense of smell, and a high degree of animal intelligence. 
They are extremely adaptable. They are omnivorous and will eat their 
own kind or even attack man if starved. They breed rapidly, having 6 to 
20 blind naked young in a litter and 6 or more litters per year which 
mature and begin breeding before the age of six months.

About the only redeeming feature of the rat is the fact that, having lived 
with man and eaten the same foods for thousands of years, they react 
alike to the same diseases and the same treatments. Special strains are 
bred and experimented upon in laboratories to find the cause and cure 
of many human ills.

Red squill, the specific poison for rats, causes other animals to vomit. 
That is one thing a rat cannot do.