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BATS
Chiroptera
Townsend's
big-eared bat © J. Scott Altenbach
There are more
than 1,100 different species of bats, representing 20% of all
mammal species worldwide. At least twenty of these bat species
are found in the Los Padres National Forest. However, their
numbers have dwindled and more than two thirds of bat species in
the region are imperiled. Protecting remaining bat populations
is important because of their vital role as insect controllers,
pollinators, and seed scatterers.
Bats vary widely in size - the smallest mammal in the world is
the bumblebee bat of Thailand (smaller than a dime), while some
of the fruit bats (also known as “flying foxes”) of the Asian
tropics can have a wingspan of up to six feet. Their shape also
varies between species and usually corresponds with food type
and highly specialized hunting or foraging habits. For instance,
certain insect-eating bats that feed over water have very
different feet, wings and ears than bats that catch insects in
mid-air. Contrary to popular belief, more than 70% of bats eat
insects, with much of the remainder being tropical species that
feed on fruit and nectar. A few are carnivorous, eating small
fish, birds and frogs. Only three species of bat are vampiric,
totally subsisting on blood, and they are only found in South
America. Sadly, bats all over the world have been targeted by
humans based upon an unfounded fear that they are vampire bats
when really they eat insects or fruit.
Bats are the only truly flying mammal species. This is part of
the reason that they roost upside-down; because they don’t have
the strength, like birds, to launch themselves into flight from
standing, they drop from a hanging position directly into
flight. Hanging upside-down also allows them to rest safely away
from predators. Some bats are solitary and travel and roost
alone or in small groups, while others prefer to congregate in
large colonies of millions of bats. They are a commuting,
migratory species, meaning they move from place to place on a
nightly basis from a few to hundreds of miles. Like humans, bats
give birth to live, helpless young and breast feed them on milk
for several months, making them, for their size, the slowest
reproducing mammals on earth. They are also quite long-lived for
their size—some species can live into their thirties!
Bat sonar (formally called echolocation) is perhaps the most
unique bat trait. Like dolphins, bats emit pulses of extremely
high frequency sound waves, which bounce back to them as echoes
and allow them to form an image of their surroundings. Most bats
even have relatively good eyesight, but use this technique to
navigate and hunt. Bat sonar is so efficient that they can
snatch flying insects from the air and navigate past objects as
small as a string in complete darkness.
Within the Los Padres National Forest, bat species vary from
“mouse-eared” bats (from the genus Myotis) to the very
large western mastiff bat. Conservation issues mainly have to do
with the availability of adequate roosts (usually trees or
caves) and feeding habitat within the distance of the nightly
commute to a new roost. The large scale urban development
surrounding the southern portions of the Los Padres limits bat
survival in many areas, and therefore looking at the entire
landscape’s interactions to inform conservation is vital.
Following are further
descriptions of bat species found within the Los Padres National
Forest that are classified as Federally Endangered (FE), Federal
Species of Concern (FSC), California Species of Special Concern
(CSC), Forest Service Sensitive (FSS), Bureau of Land Management
Sensitive (BLM), or any combination thereof.
Fringed Myotis (Myotis thysanodes) –
FSC, CSC, BLM
photo ©
J. Scott Altenbach
 Fringed
myotis is a large “mouse-eared” bat, with its name referring to
a fringe of short hairs on the edge of the membrane between its
hind legs. It can be found from sea-level to above 6,400 feet
across its general range from British Columbia to Mexico, but is
restricted to high-elevation habitats in southern California. In
the Los Padres, it was found only at high elevations above 4,600
feet and populations are very patchy throughout the forest.
Little is known about its history in this area, but it is
actually thought to have always been a rare species in the Los
Padres. Fringed myotis eats mostly insects such as crickets,
moths and daddy longlegs, and roosts mostly in rock crevices and
buildings .
Long-Eared Myotis (Myotis evotis) –
FSC, BLM
photo ©
J. Scott Altenbach
 Long-eared
myotis is also a member of the “mouse-eared” bat genus, and has
very long ears that are narrower than those of other myotis.
This bat, like its relative the fringed myotis, can only be
found throughout the upper elevations of the Los Padres, usually
in oak woodlands. The long-eared myotis eats mostly moths, flies
and beetles. It usually roosts in hollow trees, under slabs of
bark or in abandoned mines, so timber harvesting and the sealing
of mine entrances are harmful to its survival. However, a common
technique is to seal mine entrances with “bat-friendly” gates
that allow bats access to the caves, but keep humans and larger
animals out.
Long-Legged Myotis (Myotis volans) –
FSC, CSC, BLM
photo ©
J. Scott Altenbach
 Long-legged
myotis is the Los Padres National Forest’s third threatened
member of the “mouse-eared” genus. It can be recognized by its
short ears, long tail and relatively large hind feet. It occurs
mostly in the high-elevation woodlands of the Los Padres and
roosts in hollow tree snags or lightning scars during the day,
and caves or mines at night. Although the long-legged myotis,
like the fringed myotis, is likely to have always been rare in
this area, timber harvests, pesticides, and mine reclamation
activities are harmful to its survival. Its diet consists mostly
of moths, termites, beetles and flies.
Pallid Bat (Antrozous pallidus) –
CSC, FSS, BLM
photo ©
J. Scott Altenbach
 Pallid
bat is a small, pale colored bat with large eyes that has very
unique feeding habits: it feeds mostly on insects from the
ground, while most other insect-eating bats capture food from
the air. It is known to eat scorpions (it is immune to their
sting!), spiders, praying mantids, and grasshoppers and has even
been seen running across the ground chasing crickets. Pallid
bats are found at high elevations between 1,100-6,600 feet
within the Los Padres. There is strong evidence to suggest that
the pallid bat has suffered severe population declines in recent
years in our region due to the destruction of roosting sites
(human structures, mines, tree hollows). It is extremely
dependent upon its roosts for survival, and the large scale of
roost disturbance in this region may cause populations to fail
in the future.
Townsend’s Big-Eared Bat (Corynorhinus townsendii)
– CSC, FSS, FSC, BLM
photo ©
J. Scott Altenbach
 Townsend’s
Big-Eared Bat, so named for its extremely large ears, is found
throughout the Los Padres. Its distribution, however, depends
upon the availability of caves or abandoned mines due to its
large size and preference to live in large colonies. Its ability
to survive also depends on these types of roosting sites, and
its numbers are in decline due to disturbance of its
reproductive roosts. These disturbances include mining, sealing
of abandoned mines, vandalism and recreational use of caves.
Recommended conservation efforts include protection of key
roosting sites and close monitoring of population numbers.
Western Mastiff Bat (Eumops perotis californicus)
– CSC, FSC, BLM
photo ©
J. Scott Altenbach
 Western
mastiff bat’s home range extends through all of California, but
its greatest concentration historically was in southern
California. It is the largest bat native to North America, with
a wingspan of almost 2 feet, and is characterized by its
enormous ears that are joined at the base and extend over each
side of its head like a bonnet. It usually roosts in rock
crevices and large rock outcroppings on cliffs that have an
opening of at least 6.5 feet to allow them to drop in from
flight. The western mastiff bat is very dependent on wide-open
spaces for foraging for moths, its main food source, and is
affected by the limitation on foraging that urban development
causes.
Western Red Bat (Lasiurus blossevillii) –
CSC, FSS
photo ©
J. Scott Altenbach
 Western
red bat is a solitary species that roosts alone or in small
groups mainly in shrubs and small trees in habitats bordering
rivers, forests and urban areas. It has been documented along
the upper Salinas River in the Los Padres National Forest. The
western red bat is also a migratory species, ranging from Canada
to South America, only spending its summers in southern
California and the Los Padres National Forest before migrating
southwest. Because of its migratory nature, the western red bat
is very dependent upon the connectivity of habitat along its
migratory pathway and has probably suffered decline due to
habitat loss from urban expansion, reservoir construction and
agricultural conversion.
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