206 GNAWING ANIMALS 



H. Osgood dug out a burrow, of which he made a careful 

 diagram, accompanied by measurements. 



'In this case the burrow went down nearly vertically to 

 a depth of \\ x/ 2 feet below the surface, when it turned abruptly 

 and became horizontal as shown in the diagram. The hori- 

 zontal part was 13}/2 feet in length. One-third of the hori- 

 zontal part (the terminal 4 feet, F) and two old nests and 

 passageways (E) were plugged with black earth brought in 

 from the surface layer, which was very different from the 

 light-colored clayey earth in which the greater part of the 

 burrow lay. 



"Four or five feet below the entrance was a diverticulum, 

 or short side passage (G), probably used as a place in which 

 to turn around when the animals come back to take a look 

 at the intruder before finally disappearing in the bottoms of 

 their burrows. It is also used, apparently, as a resting-place 

 where they bark and scold after retreating from the mouths 

 of the burrows. As elsewhere noted, they are often heard 

 barking after they have gone in. 



'The burrow was opened the day after bisulphide of car- 

 bon had been used for destroying the animals, and the ma- 

 terial carrying the bisulphide was found at the bottom of the 

 vertical part, just where the horizontal part turns off. Two 

 dead animals were found, one in the horizontal part, the other 

 in the nest, as indicated by the letter K in the diagram. 



"The Prairie-Dog has several natural enemies which, 

 when not interfered with by man, usually serve to hold its 

 numbers in check. The most inveterate of these appear to 

 be the coyote, badger, black-footed ferret, and rattlesnake." 



