DIXON' — RODENTS IN IMPERIAL VALLEY 
145 
The breeding season of this gopher is long, extending over several 
months. According to professional gopher trappers two litters of 
young are frequently raised in one season. The average number per 
litter appears to be slightly less than six. As with the muskrats, the 
average litter is small in number, but this is more than compensated 
for by more than one litter being raised each season. 
Unlike the muskrats, gophers habitually burrow completely through 
the canal banks. They usually keep just above the water line, but when 
the water in the canal is low the gophers also burrow low, and when the 
canal is again filled, the water leaks out through the gopher hole; this 
leakage, unless discovered and stopped in time, results in a break in 
the canal and in flooding of the surrounding fields. Gophers often 
burrow through the outside of the ditch banks and thus make connec- 
tions with muskrat burrows, causing breaks in the canal for which 
the muskrat receives the blame. At the east end of the Encina flume 
which crosses New River below the line, gophers have riddled the in- 
side of the main canal which at this point is merely a dirt embankment 
built up until the crest is nearly twenty feet above the surrounding 
territory. Gopher burrows in such places are exceedingly dangerous. 
One gopher at this point could easily endanger the growing crops on 
hundreds of acres in Imperial County. A narrow cement core built 
into the center of the canal banks could be cheaply installed at such 
points and would greatly reduce the danger. 
Trapping and local or county bounties are the two control measures 
that have been most used against the gopher in this region. An officer 
of district eight reports that during four months in 1920-21 this dis- 
trict paid a bounty of twenty cents a scalp on nearly 15,000 gophers. 
Districts one and seven each employ two or more regular gopher catchers 
who are paid on a salary basis. These men trap faithfully and work 
where the gophers are doing the most damage, but the territory that 
each trapper can effectively cover is limited. The bounty system soon 
depletes the funds available and affords no permanent relief. Pois- 
oning has been tried, but has met with poor success for the most part, 
due apparently to the abundance of food such as Bermuda grass which 
has been more acceptable to the gophers than the poisoned bait offered. 
Another difficulty is encountered in the fact that the water in the canals 
is used throughout the valley for domestic purposes and care must be 
taken that the water be not polluted by poison or by dead gophers. 
However, poison experiments which have already been carried on in 
the Imperial Valley, using a probe to locate the burrow and a bait 
