114 ANIMAL LIFE OF CARLSBAD CAVERN 



worked in the cave. Two men working together could 

 fill and tie up four hundred sacks a day, the sacks 

 weighing 50 pounds each, and these were lifted to the 

 surface with engine and cable and loaded on heavy 

 wagons for the twenty-two-mile haul to Carlsbad. 



The guano was shipped to the General Fertilizer 

 Company of California, but I could get only a general 

 statement of prices ranging from twenty to eighty 

 dollars a ton. Of course the returns were not all profit, 

 but the cave was considered a valuable property until 

 the store of guano was practically exhausted. The 

 lower levels were very old, and not so rich in nitrates 

 nor so valuable as the more recent deposits. 



At the present time there is little guano in the cave, 

 probably not a dozen car loads, and it is being deposited 

 so slowly that it can not have a real value again for 

 many years. A layer of about three inches in depth 

 has been added since the work stopped four years ago. 

 Under the central part of the bat roost, on April 29, 

 1924, I spread a paper twenty by thirty inches, and 

 in 44 hours caught 1,145 of the bat droppings, each 

 about the size of a grain of wheat and all together 

 weighing 5 grams when fresh, and 3.7 grams when dry. 

 The paper was about half-covered, so that a single 

 layer about two millimeters, or a twelfth of an inch, 

 deep would at this season require about 88 hours or 

 nearly four days for deposit. 



But insect life was scarce at this season, and bats 

 taken as they entered the cave in the morning had 

 their stomachs not more than half-filled, while those 

 leaving at night showed empty stomachs and often the 



