Journal of Mammalogy 
Published Quarterly by the American Society of Mammalogists 
VoL. 1 MAY, 1920 No. 3 
CONTRIBUTION TO THE LIFE-HISTORY OF THE CALI- 
FORNIA MASTIFF BAT 
By a. Braziee Howell 
[Plates 5-d] 
Among the bats found within our borders, there is probably none 
more interesting than our largest species — the Cahfornia mastiff bat 
{Eumops calif ornicus). First discovered at Alhambra, Cahfornia, 
by E. C. Thurber, it has always been considered decidedly rare, and is 
poorly represented in even our largest museums. 
During the past year, I have had exceptional opportunities to study 
this form, and now after a great deal of hunting, which cannot better 
be described than by the word “snooping,” poking my nose into every 
likely and unlikely place, and even advertising, I have no hesitancy in 
pronouncing it a common species in the orange section or thermal belt 
of Los Angeles County. However, to be successful in finding it, one 
must employ no little energy and perseverance. Almost all of my 
observations were made in the company of L. Little, and with his 
assistance. 
I imagine that in the days before houses were built in this section, 
“mastiffs” were in the habit of roosting in cracks of occasional chffs. 
Undoubtedly, they sometimes used hollow trees as well, but not to a 
great extent, for trees with cavities high enough to suit them were any- 
thing but plentiful. At present, they may be found in a variety of 
situations, such as attics, large warehouses, or cracks in high masonry, 
but the colonies are not nearly as populous as are those of most other 
bats. I consider that twenty is rather a large number for a colony, 
although as many as seventy may be found together. I have heard 
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