RILEY — BEAVER CULTURE 
205 
planted specimens more time to become located, build a house and store 
food before winter s6ts in. 
The estimate made of the beavers in 1918 showed 12,000 in the 
streams within the vicinity of the Forest. While this may have been 
a little high at the time, it is believed to be conservative at the pres- 
ent time. Anything approaching an accurate census, however, has not 
yet been made. On streams, like Saguache Creek, which are subject 
to flooding and washing out of dams, not nearly all of the beavers 
construct dams. They often simply burrow into the bank and make 
dens without them. This fall numerous runways and cuttings of wil- 
lows were observed along the creek, and dens without dams. The 
observations of local trappers and also of the state trapper agree 
with the information given by the Biological Survey that they 
average about four kits to the litter. From information obtained from 
Mr. J. D. Figgins of the Colorado Museum of Natural History, they 
have a litter each year, and the young ones remain with the old until 
they are two years old, or until the third litter is born. This would 
indicate that there are two litters in most dams. There is one point, 
however, which has not been cleared up. That is, whether the 
secondary dams are also regularly inhabited. Some claim that the 
two-year-olds occupy them when pushed out by the parents, but there 
is a difference of opinion as to this. With the gathering of a little more 
information as to their habits, it is hoped to make a more accurate 
census, but it is going to require time and close observation. 
Likewise, there is very little information about natural losses and 
rate of increase. Estimates of the numbers in Long Branch Creek 
showed 50 beavers in 1908 and 3,000 in 1918, indicating an average 
yearly increase for the period of about 50 per cent. This, however, 
is based only on estimates. In order to be conservative, an annual 
increase of 25 per cent has been assumed until such time as more 
accurate information can be obtained. It is evident at any rate that 
they increase rapidly, judging by the new dams constructed each year. 
I have traveled for days on end through the Forests of Wyoming 
over lands of first quality for fur animal production. A trapper at 
Valley Wyoming wrote me not long ago that he had out 200 miles of 
trap lines and he was not doing so well because the martens were 
scarce. That while there was lots of feed such as rabbits and squirrels 
in the region where he was trapping, the martens were not there and he 
thought they had just been trapped out. In fact, he beheved the only 
hope for the marten is a closed season. 
