700 THE MONTHLY BULLETIN. 



Numerous holes in the sides of gullies and in the banks of washes 

 form the most conspicuous signs of the presence of the Nelson Squirrel. 

 Tracks and mounds at the entrances to burrows are not as noticeable 

 as one would expect from the number and size of the animals. Trails 

 from the burrows to the feeding grounds of this species are usually not 

 well defined. In one place near the mouth of San Emigdio Creek 

 these squirrels were obliged to cross a large dusty area in traveling 

 back and forth between their burrows and their feeding grounds. 

 Numerous tracks in this dusty spot showed that the squirrels in this 

 colony did not follow definite trails, but that each individual chose his 

 own route. In passing around a projecting bank, however, the tracks 

 were found to converge for a short distance into broad, well-beaten 

 paths six to eight inches wide. 



The favorite location for burroAvs of this squirrel is, as already stated, 

 in the sides of banks at the edges of washes or gullies. The burrows 

 usually enter near the bottom of the bank. The entrances to the 

 burrows vary from 1^ to 8 inches in diameter. The largest holes 

 are in soft ground beneath horizontal hard strata in the bank and their 

 large diameter is due at least in part to the weathering or caving in of 

 the soft earth. The burrows of smallest diameter are found in hard, 

 level ground at the roots of Atriplex bushes. The entrances to burrows 

 in the banks are from six inches to fifty feet apart. These bank burrows 

 run back in a generally horizontal direction and are interconnected to a 

 considerable extent under the bank. This was proven by seeing a certain 

 squirrel, known by sight to the observer, disappear into one hole and 

 then in a few minutes reappear at the mouth of an a-d joining burrow 

 twenty or more feet distant. 



All of the eight burrows dug into by various persons from this 

 museum have proven to be simply refuge burrows, with only one 

 entrance ; that is, not of the intercommunicating type. Squirrels were 

 found to reappear in from 5 to 15 minutes after they were chased into 

 such burrows. These refuge burrows were found to be short, less than 

 twelve feet in length; shallow, less than three feet in depth; and of 

 small size, less than two inches in diameter. In three cases the squirrels 

 were gassed in these burrows and an hour later dug out. Two of the 

 animals were found dead near the wasteball at the entrance of the 

 burrow, where they had evidently been overcome by the gas when 

 attempting to make their way out. 



No nests were found in any of the burrows that were dug out, although 

 nesting burrows were particularly sought for. Consequently we have 

 no information to offer regarding this phase of the animal 's life history. 



The Nelson Squirrels found near the mouth of San Emigdio Creek 

 were found to be moderately infested with fleas. The squirrels were 

 often seen to stretch out to their full length and roll over and wallow 

 about in the fine powdery alkaline dust which in many places was an 

 inch deep under the overhanging banks along the edges of the washes. 

 Such dust baths, which were frequently indulged in with considerable 

 evident satisfaction by the squirrels, are likely to serve in keeping the 

 pelage of the animal clean as well as to discourage the fleas. 



Our data regarding the breeding of AmmospermopMlus nelsoni is 

 scanty. The breeding season appears to be much earlier in this species 

 than in the case of the Fisher G-round Squirrel in the same region. 



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