Specimens were collected in spring in 1951 at elevations of 2800 and
3200 feet in San Antonio Canyon, on the coastal slope, and in Mescal
Canyon at 4900 feet, on the desert slope. Large, fast flying bats,
probably of this species, were seen at Jackson Lake, 6000 feet
elevation, on October 15, 1951.
Hoary bats are present in the San Gabriels in the fall, winter, and
spring. In 1951 the last spring specimen was taken on June 11, in Mescal
Canyon; then collecting was discontinued until late September when the
first hoary bat was taken on the thirtieth of that month. From this date
on into the winter hoary bats were recorded regularly. They seemed to be
as common in early June as in most of April and May; possibly some
remain in the San Gabriels throughout the summer.
In spring these bats seem to segregate by sex; of twelve kept as
specimens and at least an equal number captured and released only one
was a female. All were captured above 2800 feet.
Hoary bats seem to have a long pre-midnight forage period, having been
captured at ponds from 21 minutes after sunset, to three hours and 26
minutes after sunset. Generally those taken early had empty stomachs
and those taken later had full stomachs. On the night of May 24, 1951, a
hoary bat captured two hours and five minutes after sunset had only a
partially full stomach.
On May 25, 1951, an unusual concentration of hoary bats was observed at
a pond at about 3200 feet elevation, in San Antonio Canyon (Vaughan,
1953). The day had been clear and warm, one of the first summerlike days
of spring. Beginning at 30 minutes after sundown hoary bats were
collected until two hours and 35 minutes after sundown; in this period
22 were caught and at least as many more observed. Many were released
after being examined, whereupon they hung on the foliage of nearby
alders to rest and dry themselves. This concentration of hoary bats may
have been due to a sudden beginning of migration with a resultant
concentration of bats at certain altitudinal belts. The warm weather
might have set off the migration. On evenings that followed subsequent
hot days no such concentration of hoary bats was seen. B. P. Bole (Hall
1946:156) observed a concentration of hoary bats on August 28, 1932, in
Esmeralda County, Nevada.
Several captive _Myotis californicus_ in a jar next to a pond in San
Antonio Canyon set up a squeaking which seemed to attract a hoary bat.
Repeatedly the large bat swooped over the jar.
_Specimens examined._--Total, 12, distributed as follows: Los
Angeles County: Mescal Canyon, 4900 ft., 2; San Antonio Canyon,
3200 ft., 2; San Antonio Canyon, 2800 ft., 8.
=Antrozous pallidus pacificus= Merriam