122 ANIMAL LIFE OF CARLSBAD CAVERN 



BIG BROWN BAT 



Eptesicus fuscus (Fig. 45) 



These large brown bats, weighing twelve grams, were 

 the commonest and the only kind shot in Slaughter 

 Canyon as they came to the water tank in the evening 

 to drink. Others seen flying at the spring and at the 

 entrance of the cavern may have been the same, but 

 none was taken near there. A couple of old skulls 

 picked up on the floor of the far south end of the lowest 

 room of the cavern prove to be of this species, and 

 strongly suggest an opening at that end where they 

 could have entered without going the whole length of 

 the dark corridors. 



These medium large, dark brown bats can often be 

 recognized on the wing by their size, color, and strong 

 rapid flight. The spread is about thirteen inches 

 across extended wings. 



SILVER BAT 



Lasionycteris noctivagans 



One of these black, woolly bats, with frosted back, 

 was shot at the spring the evening of April 12, by Dana 

 Lee, and two others were seen flying along the wall of 

 Walnut Canyon a few days later in the early evening. 

 The one collected measured 275 millimeters across the 

 wings, and weighed eight grams. They are northern 

 bats, breeding in the higher mountains of the northern 

 states and Canada, and migrating to lower or warmer 

 areas to spend the winter, but whether they winter in 

 caves or go south to a warm climate is not known. 



