HOWELL — CALIFOENIA BAT ROOSTS 
175 
dusk. Their large ears give them an odd appearance and their squar- 
ish forms are not to be mistaken. They often either alight on the 
ground or hover just above it with imperceptibly vibrating wings; 
usually a sign that a Jerusalem cricket has been captured. Such bulky 
prey is carried to a favorite station, which is generally located in an old 
shed or loft, but never in the same building as the day roost. Beneath 
these spots may be found the heads and legs of hundreds of crickets, besides 
the remains of a very few other insects. I have stunned the bats with 
blows from a board as they were entering a building with crickets in 
their mouths, and shot them by the light of a pocket flash as they hung 
from the ridge and fed. They are decidedly common in the thermal 
belt and occur in old buildings where a dozen or a hundred pass the 
days together, but invariably out of sight. Hollow partitions, or deep 
cracks, where they can hide in comparative safety, are necessary to 
their comfort, and they strongly resist any efforts to dislodge them 
from such retreats. When aroused, however, they are not averse to 
scrambling forth with such agility that it is almost impossible to catch 
them as they emerge. On May 11, 1 obtained females which contained 
two large embryos each. 
In another paper (Journal of Mammalogy, vol. 1, no. 3, p. Ill) I 
have discussed Eumops, and this I believe to be the only sedentary, 
strictly non-migratory bat in the southwestern part of the state. On 
the lower deserts Antrozous and Corynorhinus may linger through the 
winter, but on this point I am entirely unqualifled to speak. Macrotus, 
as already mentioned, is considered only partly resident; and although 
some may consider that the Mexican free-tail {Nyctinomus mexicanus) 
spends its whole life in one locality, I believe that there is a seasonal 
shifting, and that further study will show that Nyctinomus is absent 
from the northern parts of its range during the coldest weather. Our 
colonies at any rate either dwindle or disappear during the winter, and 
I judge that most of those free-tails which spend the summer with us 
go south at the approach of cold weather, and that their places are 
taken to some extent by individuals from farther north. 
The free-tail is our most ubiquitous bat. Not only are its colonies 
the most numerous but the most populous, and in northern Mexico 
hundreds of thousands may occur together. Just so it has any sort of 
cranny into which it can squeeze, it is happy, regardless of whether the 
site is vacant or occupied by other species. In fact, it shows consider- 
able partiality for the company of Eptesicus and Antrozous. They may 
be crowded into the corner of an attic, or behind a wooden sign on a 
