Mammals of the San Gabriel Mountains of California Part 4

=Eptesicus fuscus bernardinus= Rhoads

Big Brown Bat

This bat was on the coastal slope from the sage scrub a.s.sociation at 1100 feet, up to 8000 feet on Blue Ridge, and on the desert slope down to the upper edge of the Joshua tree belt at 4800 feet in Mescal Canyon.

It was the most common bat at the ponds in San Antonio Canyon in May and June of 1951, but in September and October of the same year none was obtained there.

On the Pacific slope of the San Gabriels the big brown bats segregate according to s.e.x in the spring, the males occupying the foothills and mountains and the females the level valley floor at the coastal base of the range. Of 70 big brown bats captured in May and June of 1951, at the ponds in San Antonio Canyon, only one was a female. A large colony of more than 200 individuals in a barn near Covina, in the citrus belt, was composed of only females.

Times of capture of this bat at the ponds in San Antonio Canyon ranged from ten minutes after sunset to two hours and thirty minutes after sunset. Generally these bats came to the ponds in groups of several individuals, and often more than a dozen were captured in the course of an evening's collecting.

_Specimens examined._--Total, 7, distributed as follows: Los Angeles County: Mescal Canyon, 4800 ft., 1; San Antonio Canyon, 2800 ft., 2; Covina, 1100 ft., 4 (2PC).

=Lasiurus borealis teleotis= (H. Allen)

Red Bat

One female was taken on September 30, 1951, in San Antonio Canyon, at 2800 feet elevation. The descriptions which the citrus growers of the Claremont and Glendora vicinity give of the bats they find occasionally hanging in their citrus trees accurately describe this species. Its seasonal occurrence there is unknown.

=Lasiurus cinereus cinereus= (Pasilot de Beauvois)

h.o.a.ry Bat

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.

h.o.a.ry 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 h.o.a.ry bat was taken on the thirtieth of that month. From this date on into the winter h.o.a.ry 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 s.e.x; 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.

h.o.a.ry 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 h.o.a.ry bat captured two hours and five minutes after sunset had only a partially full stomach.

On May 25, 1951, an unusual concentration of h.o.a.ry 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 h.o.a.ry 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 h.o.a.ry bats may have been due to a sudden beginning of migration with a resultant concentration of bats at certain alt.i.tudinal belts. The warm weather might have set off the migration. On evenings that followed subsequent hot days no such concentration of h.o.a.ry bats was seen. B. P. Bole (Hall 1946:156) observed a concentration of h.o.a.ry 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 h.o.a.ry 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

Pallid Bat

The pallid bat is probably the most common and characteristic bat of the citrus belt at the Pacific base of the mountains. Only once, on May 4, 1951, was this bat taken in the mountains. On that night two individuals were collected at 2800 feet in San Antonio Canyon. All of the other specimens and observations were from colonies in old barns and outbuildings in the citrus belt where these bats are found in spring, summer, and fall.

The impression gained by examining many mixed colonies of _Antrozous_ and _Tadarida_ was that the former greatly outnumbered the latter. For example, a small colony of bats in an old barn near San Dimas Wash consisted of about thirty pallid bats and five freetails.

Large numbers of wings of moths of the family _Sphingidae_, and legs and parts of the heads of Jerusalem crickets (_Stenopelmatus fuscus_) were beneath an _Antrozous_ night-roosting place in a barn near Upland.

Pallid bats were collected in 1951, from April 16 to October 17 but probably were active in the area into November.

Each of two pregnant females taken two miles northeast of San Dimas on April 20, 1951, carried two embryos 4 millimeters long.

_Specimens examined._--Total, 6, distributed as follows: Los Angeles County: 2 mi. NE San Dimas, 1200 ft., 2 (1PC); Ontario, 1100 ft., 4 (3PC).

Family MOLOSSIDAE

=Tadarida mexicana= (Saussure)

Mexican Free-tailed Bat

This bat, regularly met with in the citrus belt at the coastal base of the range, occurred in small numbers with colonies of _Antrozous_, and was once found with a colony of _Eptesicus_ near Covina. None of the females taken in April 1951 was pregnant.

_Specimens examined._--Los Angeles County: 2 mi. NE San Dimas, 1200 ft., 4.

=Eumops perotis californicus= (Merriam)

Mastiff Bat

H. W. Grinnell (1918:373) mentioned individuals collected at Sierra Madre (at the coastal base of the San Gabriels west of the study area), and Sanborn (1932:351) reported specimens from Covina and Azusa.

Probably this bat occurs locally all along the coastal base of the range.

Family LEPORIDAE

=Lepus californicus bennettii= Gray

California Jack Rabbit

This species was found in the coastal sage belt from Cajon Wash west to San Gabriel Canyon and was most plentiful in thin stands of sagebrush, and in and around citrus groves. Because of their preference for semi-open country, jack rabbits are absent from much of the coastal belt of sagebrush where the brush is fairly continuous, and they never were observed in the chaparral a.s.sociation.

Coyotes catch many jack rabbits and regularly forage around the foothill borders of the citrus groves for cottontails and jack rabbits.

A female examined on February 19, 1951, was pregnant, and one taken on March 15, 1951, carried three small embryos.

_Specimens examined._--San Bernardino County: 2 mi. NW Upland, 1600 ft., 3 (PC).

=Lepus californicus deserticola= Mearns

California Jack Rabbit

There was sign of jack rabbits along the desert slope of the San Gabriels up to about 6700 feet, one-half mile west of Big Pines. They were fairly common in the Joshua tree belt, occurred less commonly in the juniper belt, and were present locally in small numbers in the pinyon-juniper a.s.sociation.