Western Red Bat: Lasiurus Blossevilliix

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Image of the western red bat

The western red bat is a tree bat closely associated with cottonwoods at altitudes below 6,500 feet in riparian areas.

They particularly favor roosts where leaves form a dense canopy above, and branches do not obstruct the flyway below the bats.

Western red bats, particularly in California’s Sacramento Valley, are also known to roost in orchards. Despite their bright amber color, when they curl up in their furry tail membranes to sleep.

This species lives in solitary, like all tree bats, coming together to mate and migrate. Western red bats often give birth to twins, and there can be litters of up to four pups for western red bats, although three are the average.

Typically, these bats feed along forest edges, in small clearings, or around street-lights where moths are preferred. ¹

Learn More: Species Of Bats

Western Red Bat Physical Characteristics

Upper urface of tail/hind feet are thickly furred
Ears: 1.0-1.5 cm long.
Fur Color: varying from orange to rusty red
Total length: 11.0 cm; wingspan: 28.0 cm; weight:11 grams
Dense fur on the back is long and soft

Diet Of The Western Red Bat

1-2 hours after dark, western red bats begin to forage, and the food search may last until the following morning.

Western red bats tend to feed 600-1000 yards from their roosting site and will forage from a few feet above the ground to tree-top level.

Moths are one of the main prey items, but flies, bugs, beetles, cicadas, and ground-dwelling crickets are all food options. To capture prey, they use their wing membranes and will land on vegetation to catch an insect.

Echolocation, including narrow and wideband calls, is used to find prey. They use long calls with a low pulse repetition of narrowband frequencies when searching.

Western red bats will hang around light sources which attract insects. The bats are intelligent and will return to the light source if the insect population is constant. ²

Western Red Bat Habitat

Western red bat roosting sites are in the foliage of forest trees and shrubs, typically 1.5 to 12 m above the ground.

The western red bat’s perfect roosting tree is dark and sheltered above the roost seat for predator protection and clear below the roost, allowing the bat to quickly exit the tree.

The bat often relies on roosting and foraging riparian trees and has been linked to mature cottonwood, sycamore, and willow that stand adjacent to streams. Some fruit trees in orchards have also been associated with western red bats, and some evidence has indicated that they may use caves occasionally. ³

Range Of The Western Red Bat

The red bat is locally abundant in California, appearing from Shasta County, CA, to the Mexican border, west of the Sierra Nevada crest and deserts.

Migration occurs between summer and winter, but migrant bats may be found outside the typical seasons.

Since these bats require forested areas, they will not be found in deserts. Males and females occupy different areas during warm months but come together in the winter. ⁴

Behavior Of The Western Red Bat

This species lives solitary for most of its life, except during mating season and when a female cares for its young. During foraging and migration, temporary associations occur.

Western Red Bat Communication Methods

Photo of western red bat roosting on a tree

While there has been no study of this species’ communication, several anecdotal observations suggest that vocal and chemical signals play a role in regulating social encounters.

The same perches used by red bats during previous nights may be selected by migrating individuals, perhaps responding to chemical indications placed on the perch.

Probable sources of substances are the four sets of facial glands. Red bats chirp and squeak in flight, as well as emit high-frequency sound pulses. They produce raspy, buzzy sounds when handled by humans. ⁵

Western Red Bat Reproduction

There is little known of the mating habits of the western red bat. Related bats have an enormous range of mating patterns, so how the western red bat mates is challenging to say.

Red bats in a litter can have up to five pups. They mate in late summer to early fall, when there are the most insects available to eat. From mating until after hibernating through the winter, women can store the sperm to have the pups when the weather is warm, and insects are available again.

The parental care of western red bats is not very well known, but a related bat, Lasiurus borealis, has been studied and probably has similar habits. During the day, while hanging from a tree or shrub, a Lasiurus borealis mother lets her young cling to her. As they cling to her, other babies also hang from twigs or leaves.

The young are always moving during this period by stretching, cleaning themselves, or interacting with their mother. During this time, she provides milk for them as well. It lasts for a while until the kids are 90% of their adult size. ⁶

Predators Of The Western Red Bat

This bat species has a shortlist of predators due to the bat’s ability to escape danger and strategically choose roosting sites based on the availability of escape routes.

Typical nests will be situated well above ground level to prevent land-bound animals from attacking the western red bat off spring.

Top 5 Red Bat Predators

Roadrunners
Opossums
Feral cats
Falcons
Scrub jays

Sources:

Bat Conservation International. “Lasiurus Blossevillii.” Bat Conservation International, 1 July 2020, www.batcon.org/bat/lasiurus-blossevillii.
“Western Red Bat.” Lower Colorado River Multi-Species Conservation Program, www.lcrmscp.gov/species/western_red.html. Accessed 9 Dec. 2020.
Lavender, J. 2014. “Lasiurus blossevillii” (On-line), Animal Diversity Web. Accessed December 09, 2020 at https://animaldiversity.org/accounts/Lasiurus_blossevillii/
Harris, J. “California Wildlife Habitat Relationships System.” Animal Diversity, nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=2339. Accessed 9 Dec. 2020.
Communications, Esf Office Of. “Red Bat | Adirondack Ecological Center | SUNY ESF | College of Environmental Science and Forestry.” SUNY College Of Environmental Science And Forestry, 1988, www.esf.edu/aec/adks/mammals/red_bat.htm.
Lavender, J. 2014. “Lasiurus blossevillii” (On-line), Animal Diversity Web. Accessed December 09, 2020 at http://www.biokids.umich.edu/accounts/Lasiurus_blossevillii/