HOWELL^ — CALIFOENIA BAT ROOSTS 
173 
Although the leaf-nose is a very late flier and I have never heard of 
it being observed hunting before complete darkness sets in, we found 
the wings of several diurnal butterflies, as well as parts of moths, be- 
neath their roosts. The sexes have been found together only during 
the mating season. It is not a species that is strictly migratory, and 
may not be so at all, for a colony will spend the winter — apparently in 
a perfectly active state — in a deep cave, the temperature of which 
never varies greatly. Shallow caves are, however, deserted at the 
approach of cold weather; and, judging by the seemingly reduced winter 
population, it is possible that some of the bats at this season may seek 
a warmer climate. 
Some six hundred Yuma bats {Myotis yumanensis yumanensis) 
were found at the one and two-hundred foot levels of, the old Senator 
Mine on the Colorado River. Nearer the surface many were chnging 
singly to the walls, and these were in a sound sleep, squirming but feebly 
when plucked off like ripe fruit. Nearby there were a few lively ones, 
and those in bunches at the deeper levels were all active. The latter 
were gathered in two knots of a hundred each and one lot of over three 
hundred, in a compact mass, on the uneven roof of a chamber. When 
these were approached too closely, the bats swarmed off in every direc- 
tion, bumping into and crawling all over us. The species is a very late 
flier and I have never seen it awing before dark. 
There is a colony of Tejon bats {Myotis yumanensis sociabilis) in 
an old adobe store-house at Fort Tejon, Kern County. A new gal- 
vanized iron roof was put on this building some years since and the 
bats are now distributed in the cracks along the peak. On September 
3 there were at least a thousand of them present and I swept many of 
them into a sack with my bare hands as they congregated in clusters 
against the angles of the rafters. They were quick to slip into cracks, 
and when poked at they catapulted forth, and, as often as not, flew 
directly in my face. On September 23 there were only two hundred 
left, and by December 16 all had departed. No adult males were 
secured in this colony. Beyond doubt this form is entirely migratory. 
With us, the large brown bat {Eptesicus fuscus fuscus) is the com- 
monest of the early fliers during spring and fall, but during the winter 
it is either absent or very rare. I suspect that this species is rare on 
the floor of the valley in midsummer as well, but I am usually away at 
that season. Their abundance may be more apparent than real, as 
they put in an appearance early and are such big, conspicuous fellows, 
they seem to be ever 3 rwhere. I have first noted them on warm eve- 
