DIXON — KODENTS IN IMPERIAL VALLEY 
141 
of about eight dollars each in ordinary years, and in 1920 large raw 
skins sold for as much as twenty dollars. There appears to be no good 
reason why the beavers should not be removed wherever they are endan- 
gering the canal banks. The value of the pelt should defray the cost 
of the trapping if this is done at the proper season when the fur is 
prime and hence of greatest value. 
In April, 1894, Dr. E. A. Mearns saw what he believed to be muskrat 
sign near Seven Wells on the Alamo (Salton) River. It is probable 
that a few muskrats existed along this stream prior to the construction 
of the Imperial irrigation system. Muskrats are now to be found in 
all of the main irrigation canals carrying over ten second feet of water 
between Salton Sea and the Gulf. 
A conservative estimate based upon careful investigation places the 
present muskrat average population per mile as follows: Large main 
canals, 40; small mains, 20; Alamo River, 20; New River, 40 (and in 
places up to 200 per mile). In 1920, 67 muskrats were actually trapped 
during a single night in a distance of one mile along New River, and 
at least twice as many were left untrapped. Over 400 muskrats were 
taken by one trapper in twenty nights on the Brawley main. This 
trapper set his traps only one night in each place, and trapped about 
one mile of canal a night. In three months, W. W. Morrison and 
assistant, caught 1738 muskrats. From the known number of trappers 
and their catch it is conservatively estimated that 25,000 muskrat 
pelts were shipped out of the Imperial Valley during the trapping 
season of 1919-20. It is further believed that the catch (25,000) 
equaled one half the total population of muskrats. 
Muskrats breed every month in the year in the Imperial Valley. 
Small woolly Juvenals barely able to leave the nest and forage for 
themselves have been caught in mid-winter, and small young have 
been trapped during every month of the year. The bulk of the young 
are born between February 15 and October 30. Three and possibly 
more litters are raised in one year. The litters are relatively small. 
The average number of embryos in twenty-three pregnant females was 
six, with three and nine as extremes. 
In the Imperial Valley muskrats live and forage entirely within the 
canals and other waterways. The writer has been unable to find a 
single instance where muskrats have gone out from the canals and 
injured growing crops in the adjoining fields. The favorite food of 
this rodent consists of the natural vegetation, such as cat-tail and 
grass roots, which grow along the inner banks and tend to clog up the 
