10 BULLETIN 1091, U. S. DEPARTMENT OF AGRICULTURE. { b1u1i.^No!'i, 



ing heights above the general surface of the surrounding soil, the 

 height depending rather more upon the character of the soil and the 

 location of the mound as to exposure or protection than upon the 

 area occupied by the burrow system which lies within and is the 

 reason for the mound. 



A den in sandy soil in the open may be of maximum size in area 

 occupied and yet scarcely present the appearance of a mound in any 

 sense, due probably both to the fact that the sandy soil will not heap 

 up to such a height over a honeycomb of tunnels as will a j&rmer or 

 rocky soil, and also to its greater exposure to the leveling action of 

 rains and the trampling of animals. These mounds are in themselves 

 large enough to attract some attention, but their conspicuousness is 

 enhanced by the fact that they are more or less completely denuded 

 of vegetation and are the centers of cleared areas often as much as 

 30 feet in diameter (PI. V, Fig. 1) ; and further that from 3 to 12 

 large dark openings loom up in every mound. The larger openings 

 are of such size as to suggest the presence of a much larger animal 

 than actually inhabits the mound. Add to the above the fact that 

 the traveler by day never sees the mound builder, and we have the 

 chief reasons why curiosity is so often aroused by these habitations. 



On the Eange Eeserve the mounds are usually rendered conspicuous 

 by the absence of small vegetation, but Nelson writes that in the 

 vicinity of Gallego, Chihuahua, they can be readily distinguished at 

 a distance because of a growth of weeds and small bushes over their 

 summits, which overtop the grass. In the vicinity of Albuquerque, 

 N. Mex., Bailey reports (and this was recently confirmed by Vorhies) 

 that the mounds about the holes of spectabilis are often hardly 

 noticeable. Hollister writes that in the yellow-pine forests of the 

 Gallina Mountains the burrows are usually under the trunk of some 

 fallen pine, both sides of it in some cases being taken up with holes, 

 there being some eight or ten entrances along each side, the burrows 

 extending into the ground beneath the log. In the vicinity of 

 Blanco, X. Mex., Birdseye saj's that occasionally spectabilis makes 

 typical dens but more often lives in old prairie-dog holes {Cyno7nys) , 

 or in holes which look more like those of D. ordii. » 



Runways and Tracks. 



Still other features add to the interest in the dwelling places of 

 spectabilis. Radiating in various directions from some of the open- 

 ings of the mounds well-used runways are to be seen, some of them 

 fading out in the surrounding vegetation, but others extending 30, 

 40, or even 50 or more yards to neighboring burrows or mounds (PI. 

 V, Fig. 2; PI. VI, Fig. 1). These runways and the entrances to the 

 mounds are well worn, showing that the inhabitants are at home and 



