Yellowstone Beaver 191 



These localities, together with a number of smaller ponds near by, 

 harbor many colonies of beaver and represent a great variety of 

 conditions. They are all easily accessible to the tourist by either 

 roads or trails. 



Colony near Yellowstone Bridge. The group of ponds paral- 

 lelling the Cooke City road, near the Yellowstone Bridge (figure 37) 

 is the one which visitors to Camp Roosevelt are most likely to see. 

 If they do not make a special visit to the ponds they are almost sure 

 to pass them on the way to the Yellowstone or Lamar rivers on 

 fishing trips. Therefore a somewhat detailed account of them may 

 not be out of place here. Mr. M. P. Skinner, the Park Naturalist, 

 informs me that there were no beaver at this place ten years ago, so 

 that all the work here has been done within that period of time. 

 Here is a steep, narrow gulch, with a small stream of water, and 

 formerly densely set with aspens, along which have been constructed 

 about twenty dams of various lengths, making a series of ponds 

 which form a continuous waterway for several hundred feet. There 

 are two lodges, and in one pond beaver were living in burrows whose 

 entrances were protected by log-piles (figure 38). In this pond there 

 were at least three beavers, an adult and two yearlings. Quite pos- 

 sibly there may also have been another adult. In one of the lodges 

 were 2 adults, 3 yearlings, and 3 of the season's youngsters. 



A question often asked is : Why do the beavers have so many 

 ponds ? There are several reasons for this. In the first place, these 

 ponds were most probably not all built at ■ once, but successively, 

 those lowest downstream first. As the green aspens growing in the 

 gulch and on the hillside were cut down and used for food, the 

 animals had to move upstream to get nearer the food supply and so 

 more dams were built. A beaver always prefers to travel in the 

 water when it can ; it is too much at the mercy of its enemies when 

 on land, and also it can float sticks along a pond to the dam, drag 

 them over the next to the pond below, and thus take them wherever 

 desired. As practically all the green aspens in this gulch near the 

 water as well as on the adjoining hillside are now cut, there is but 

 little available food unless the animals go some distance above the 

 uppermost ponds, where the space is too narrow and the slope too 

 steep to make s : zable pools. They do appear, however, to be work- 

 ing that way. Their other alternative is to go across the road to 

 the large grove on the hillside above, and opposite the ponds (figure 

 39). They have cut down some trees there, but it is a dangerous 



