34 BULLETIX 1091, U. S. DEPAETMEXT OF AGRICULTURE. {-^^ 



echnical 

 Bull. No. 1, 



trapping for spectaljiJis on its own characteristic mounds one catches 

 a large percentage of merrinmi. 



On two separate occasions ^'orhies has observed the smaller species 

 running over the mounds of the larger, actually carrying away the 

 grain which had been placed to entice the larger when it might 

 appear. (In these cases the larger species did not put in an appearance 

 until near morning.) Furthermore, the dens of merriaml are often 

 connected by distinct runways with those of spectabilis. indicating 

 much traveling or visiting. That this is probably not fi-iendly visit- 

 ing is suggested by the certainty with which an individual of the 

 larger species will strike and kill one of the smaller when the}^ are 

 placed together in the same inclosure. The word "thief" expresses 

 this suspected relationship better than Avould the term " parasite. '' 



It is not to be expected that such obvious shelter retreats as the 

 mounds of spectabUis should fail to attract the attention of other 

 animals. We have found a small gecko {Coleonyx variegatus), 

 scorpions of two or three undetermined species, and certain in- 

 sects (of the Order Orthoptera) to be very common inhabitants 

 of the dens. "With the exception of the parasitic insects the most 

 common are wingless locustids {CeuthopMJus spp.) and the pecu- 

 liar wingless females of a species of cockroach {Arenivaga erratlca). 

 These two are seldom absent when a burrow is excavated, the female 

 cockroaches being abundant, although the winged males have never 

 been taken in the burrows. 



Gary's observations at Monahans, Tex., and those of others at 

 numerous localities, combined with our own, show that at A^arious 

 times the dens furnish protection and shelter for various species 

 of cottontail rabbits {Sylvilagus). ground squirrels (C/'teUus and 

 Am?nospermo])hiJus) , wood rats iNeotoinci). grasshopper mice 

 {Onychomys), rattlesnakes (Crotalus). and most of the common 

 lizards. Of these the ground squirrels CiteUus tereticaudus and 

 ArmmxosperTriopMlus harris'd are most often noted on the Range Re- 

 serve using the dens as a retreat, the ATnmospermophilus seldom 

 being observed to enter any other kind of burrow. It should be 

 added that the total observations include dens which have been 

 deserted by their rightful owners. 



NATURAL CHECKS. 



The enemies of the kangaroo rat are not determined in detail, or 

 as to relative importance, but the badger {Taxidea taxus herlan- 

 dAeri) and the kit fox, or swift {Vulpes macrotis neomexicana) . 

 may well be foremost. Dens which have been deeply excavated by 

 badgers are frequently seen, and sometimes two or three badger 

 tunnels penetrate one burrow system. Dens thus despoiled are 



