172 
JOURNAL OF MAMMALOGY 
young were found in the breeding area, while the males had sought a 
higher zone. 
If a colony of bats is located in an attic, the spots which to us appear 
most favorable are often unoccupied. When a particular site is once 
chosen, a little use will fix the bat scent and it will always be selected 
thereafter. The surface against which the little bodies rest becomes 
smooth and oily, and often there will be deposits of urine salts a half 
inch thick. Ectoparasites usually abound, but, as far as I am aware, 
they are of species which cannot survive upon human hosts. An 
abandoned roost is rare and it is almost impossible to drive the tenants 
from a favorite home. Only the most persistent persecution and re- 
peated raids will have any effect, and even if the whole colony is anni- 
hilated others will often take possession the following year. A colony 
of bats is a decided asset, especially in a district where there are manj^ 
mosquitoes, and it should be broken up only when the annoyance from 
its presence becomes very great. 
The California leaf-nose {Macrotus californicus) is a common desert 
bat and is found only in caves and old mines. Probably it would be 
nearly as common in the San Diegan coast region if natural caves were 
not so scarce. The Salton Sea section is an especially fine locality for 
it, for here there are many caves which the long-departed waves at 
sea level have tunnelled out of the rocky coast line. Most of these 
caves are rather shallow and nearly all are tenanted by colonies of this 
bat — from a score to two-hundred individuals to a colony. They 
hang singly from the roof by their long legs and are very alert to escape 
an approaching danger. WEen one is within thirty feet of them away 
they go, circling about and dashing out from the entrance to the cave. 
If one remains quiet a few will return and hang to a horizontal surface, 
gently fanning half-closed wings and twisting about on one leg with 
their heads turning in every direction to watch for danger. When alight- 
ing they do not catch hold by the thumbs and then turn about head 
downwards, but “flip up” just as they alight and hang directly by their 
feet. It is significant that these bats have very long legs, and that the 
long-legged European Rhinolophus also uses this method of alighting. 
This habit is doubtless a necessity to species that hang directly from a 
horizontal surface, and this method of roosting probably tends to 
lengthen the legs. It is perhaps a rule that bats with exceptionally 
long legs are free hangers; or, in other words, that they hang by the 
feet without support from any other part of the body. 
