Gormpson 110. Carlsbad Cavern Big Canyon Apr. 24, 1931. Sigon, Knight, Thompson Speaking of the Blacktailed Prairie Dog which we saw between Carlsbad & the Caverns Sigon explained the "pipe holes" The "prairie dog" digs its hole at an angle & removes the dirt through this hole. Then it digs straight up from the bottom of the shafting shaft to the surface of the ground, or earth. Above the shafting shaft. This leaves just the "pipe hole" entrance for safety, since a snake would have a difficult time going down a vertical shaft. Sigon does not believe in the air chamber escape during flood, but thinks the dog simply plugs up its hole somewhere under the ground until the water fades away. He has seen & caught a few Black-footed Ferrets in Prairie Dog colonies. The ferret has a wide distribution