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WALTER LOUIS HAHN. 



by other bones, were scattered among the rocks in a manner in- 

 dicating that the animals had probably died where they hung 

 suspended from the roof of the cave and that they had not 

 reached the place by accident nor been killed all at one time by 

 a single catastrophe. The age of the remains is difficult to deter- 

 mine. The cave itself is of comparatively recent origin and the 

 bone deposit is evidently much more recent. However, some of 

 the bones must have been there for a considerable period, since 

 they were covered with a deposit of calcium carbonate more than 

 a millimeter in thickness. The remains may indicate that the red 

 bat is a decadent species, represented by fewer individuals at 

 present than in the past, or they may indicate that it has aban- 

 doned the cave-dwelling habit in recent times. 



During the summer all of the cave-inhabiting species resort 

 to other places, finding temporary homes in attics, deserted build- 

 ings, hollow trees and dark nooks in the forest. Merriam ('87) 

 and Miller ('97) have shown that some of the tree-inhabiting 

 species migrate, and there is evidence that Myotis hicifiigus does 

 also. Just after most of the bats of this species left the Shawnee 

 Cave, about the end of April, 1907, there was a period during 

 which very few were seen flying about in the evening. A few 

 weeks later they were again seen in abundance. It seems probable 

 that the animals which wintered at this place migrated farther north 

 and that the summer residents had passed the winter elsewhere. 

 Howell ('08), describing the diurnal migration of bats near Wash- 

 ington, D. C, states that some of those observed were small and 

 apparently belonged to the genera Myotis or Pipistrellns. He 

 further states that more than a hundred bats were seen between 

 9 and 10 a. m. on September 28, 1907. All were flying with 

 the wind in a southwesterly direction, at a height of from 150 

 to 400 feet. Their manner of flight was unusually steady and 

 consisted chiefly of a sailing or drifting motion with only occa- 

 sional zigzag movements. 



The number and relative abundance of the different species 

 vary without any relation to the size or physical condition of the 

 cave. Mammoth Cave was visited in November, 1 907. In a hasty 

 examination of a part of Little Bat Avenue, about 1,000 bats 

 were seen. These were apparently all M. lucifiigiis. The guides 



