28 BULLETIN 1091, U. S. DEPARTMEXT OF AGEICULTURE. { buR^No!^!, 



The following plants not represented in the list stored by the 

 kangaroo rat on the Range Reserve have been found in the cheek 

 pouches or mounds of spectahilis in other localities : 



Amaranthus palmeri, Sesuvkini portulacastrum, and Atriplex icriglitii (allu- 

 vial soil of Santa Cruz Valley, Continental, Ariz., Bailey). 



Cut leaves and stems of a small sagebrush (Franklin Mountains, Tex., Gaut). 



Gutierrezia heads (San Juan Valley, N. Mes., Birdseye). 



Verbesina enceliodes, Portulaca olei-acea, Bouteloua gracilis, and Munron 

 squarrosa (Rio Alamosa, N. Mex., Goldman). 



Tops of buds of Artemisia fiUfolia (Mesa Jumanes, N. Mex., Gaut). 



Tumbleweed (Amaranthus graecizans), Russian thistle (Salsola pestifer), 

 Munroa squarrosa, and 8i)07-o'bolus cryptandrus strictus (Sandia Mountains, Al- 

 buquerque, X. Mex., Vorhies). 



BURROW SYSTEMS, OR DENS. 



The burrow S3'stem, or den. in which spectat'ilis stores its caches of 

 food materials, has its nest, and remains throughout the hours of day- 

 light is a complicated labyrinth of tunnels. Ejection of refuse and 

 soil from this retreat builds up the mound frequently referred to. 

 These mounds are, as Bailey says, characteristic of the species, and 

 are as unmistakable as muskrat houses or beaver dams, and as care- 

 fully planned and built for as definite a purpose — home and shelter. 

 They are, furthermore, the most notable of all kangaroo rat dwelling 

 places (Nelson, 1918, 400). They range in height from 6 inches to 

 approximately 4 feet and from 5 to 15 feet in diameter. 



The mound is built up not onl}- through the cleaning out of chaff 

 and other food refuse, but through extension and modification of 

 the tunnels : old tunnels, entrances, and caches of musty food material 

 are from time to time closed up and others excavated, repair and re- 

 building being especially necessary after the collapse of portions 

 of the den as a result of heavy rains or trampling by cattle. Ejected 

 material is most commonly simply thrown out fan-wise from the 

 openings, without much apparent effort to add to the height of the 

 mound. 



There are usually from 6 to 12 entrance holes in each mound 

 opening into the subterranean burrow system, each hole from 4 to 

 5^ inches in diameter. These holes are nearlj^ all situated a little 

 above the surface of the surrounding soil, and as Price has suggested 

 (in Allen, 1895, 213), this is doubtless a wise provision against flood- 

 ing, as torrential rains sometimes occur in the kangaroo rat country. 



Both Bailey and Nelson state that as a rule several of the holes 

 are closed with sand or miscellaneous earth and old storage material 

 during the daytime, but our observations on the Range Reserve are 

 that such closing is only occasional. Many occupied dens have not 



