90 COMMISSION OF CONSERVATION 
It is said that the best salt marshes will furnish 50 rats a year per 
acre. They may be fenced with 14-inch mesh wire, 5 feet wide, by 
burying it a foot on dry land and deeper near water area. Not more 
than 50 rat houses, or pairs, should be kept on an acre. It is necessary 
to have an area of water which does not freeze to the bottom. This, 
in many cases, could be secured by dredging and the mud thrown up 
would be used by the rats for making homes. Wild rice, water lilies, 
cat-tails, and various roots, are their natural food. Carrots, beets, 
turnips, apples, pumpkins and other cheap vegetables and fruits may 
be grown in nearby fields for summer food, or stored in pits for winter. 
A small quantity of meat may also be fed. 
The muskrat probably has only two litters a yea: in the colder 
parts of Canada, but farther south, three litters are born, and the first 
litters bear young in the autumn. The first are born about the middle 
of May and each litter numbers from four to nine, although as many as 
twelve have been reported. 
BEAVER 
(Castor Canadensis) 
The beaver formerly existed over nearly all the continent of North 
America. It was also found in Europe and the greater part of Asia and 
Northern Africa, but, in most of these, became extinct centuries ago. 
There are only a few colonies in Europe at the present time and these 
are preserved carefully by government authorities. It israpidly becom- 
ing extinct in America. The homes of the greatest numbers, at the pre- 
sent time, are in the country between the Great lakes and the St. 
Lawrence river northward to Hudson bay, and in noithern British 
Columbia. 
No animal did more than the beaver to effect the colonization of 
America. It lured men into the most remote wildernesses, furnished 
him food and clothing, and was one of the chief articles of commerce 
with Europe. So universal an article of trade did it become that, in 
northern Canada, beaver skin became the unit of currency. 
Brass estimates the world’s production as follows: America, 80,000 
skins; Asia, 1,000; Europe, a few. Besides the skins, the castorum, 
or dry beaver castor, is traded in, bringing from $12 to $15 a pound 
at the present time. 
Because of its interesting habits, every schoolboy is well 
Uses of acquainted with most phases of the life of the beaver. Its 
the Beaver 5 Fi 
flesh, skins and castors are valuable, the latter being used 
as a base in perfume manufacture. The flesh is excellent and the 
tail is considered a delicacy. The skin was formeily used in the manu- 
