SOME INTERESTING BEAVER DAMS IN COI.ORADO 43 1 



water there above the dam, and throws the swifter current to the 

 other side in the shallow water. Then the lower dam, turning 

 most of the water back to the south side, keeps the water deep 

 under that bank. 



These 2 dams backed the water up for more than 200 feet, 

 and the pond thus formed was apparently inhabited or used by 

 quite a colony of beavers. On the south bank were several 

 trails leading back from the river, and 75 feet above the dam 

 was a lot of willow brush stored in the water, the large ends of 

 the branches stuck into or against the bank and the small ends 

 lying out into the pond (PI. xxix, fig. i). These branches 

 were anywhere from 3 to 7 or 8 feet long, and as they extended 

 along the bank for a distance of 100 feet or more in water 4 

 feet or more deep, and were laid from the bottom to above the 

 surface, it is easily seen that the animals had done much work 

 in getting their winter's supply on hand. Near the upper end 

 of this brush was a house or lodge, or at least I supposed it to 

 be such, though it was somewhat different from any others that 

 I have seen, being in a clump of willows (the willows here are 

 not trees but bunches or clumps of small stems growing from 

 one or more roots, sometimes to a height of 12 feet or more). 

 Among the stems of this clump of willows the mud and sticks 

 seem to have been piled up to a height of 3 feet and the mud 

 well plastered dow^n. It stood a few feet back from the stream, 

 but between the latter and the house was a little channel and 

 there was one on either side, and these channels all showed 

 signs of constant use by beavers, as the water was so shallow 

 that in going through, the animals' bodies left clear indications 

 of their passage on the soft bottom. 



Returning now to the dams, or rather to the slough a short 

 distance below them, which was 4 feet wide, it will be seen 

 (PI. XXV) that there is one dam across the slough and then 

 farther along a dam beside it. This latter was at a low place 

 in the bank and prevented an overflow to the east, but a little 

 farther south was an overflow into a small ditch across which 

 the beaver had thrown a small dam hardly 2 feet long. This 

 last looked to me like a waste of labor for I could not see any- 

 thing gained by it. This marked the limits of the flooded land 

 here. 



