Bat – a Colonial Insectivore

Bats are the only flying mammals. Wing membranes are attached to their fingers. After rodents, they are the largest order of Earth animals. 

Microbats live in California. they are insectivores and can eat their weight in insects daily. (Large bats, such as the Fruit Bat, also known as a Flying Fox, live in tropical climates.)

Roost/Colony:

Roosts, which can contain up to thirty generations of family members, are used for protection, warmth, grooming, eating, resting, and mating. Roosting sites include caves, mines, bridges, buildings, crevices, and tree hollows. Bats are nocturnal. They leave their roosts at dusk to hunt and drink water at night.

Since roosts are where large numbers of bats congregate, it’s a system that provides fertile conditions for the spread of diseases such as, rabies, histoplasmosis, and other viruses. Roosts are where White-nose syndrome is spreading (see below).

The Mexican free-tailed bat or Brazilian free-tailed bat (Tadarida brasiliensis) is a migrating bat native to the Americas. Since it roosts in large numbers in few locations, it’s vulnerable to habitat destruction. This bat is considered a species of special concern in California because of declining populations.

Environmental Obstacles:

A keystone species, bats keep ecosystems healthy by controlling insect populations, but they’ve got obstacles. Habitat loss and destruction of roosting sites, wind farms on migratory pathways, and drought are a few.  White-nose syndrome, a muzzle and wing flesh-eating fungus, has decimated bat populations across North America.

Some good news for California bats may be forest lands opened up by wildfires.  UC Berkeley postdoctoral researcher Zachary Steel found that certain bat populations have increased in burned forests. The causes are still under study but causes may be increased food sources, roosting locations in dead trees, and/or more space for flight maneuverability 

Special Adaptations:

Bats hunt with echolocation, sounds out of human hearing range that help locate prey.

While bats can use their mouths to catch prey, most bugs are caught in their wing membranes and either eaten in the air or carried to a roosting spot.

Bats have bendy bones which makes them ultra maneuverable. Some say bats have the fastest horizontal flying speed of any animal, close to 99 miles per hour!

Among roosting bats that create large quantities of urine and guano, they’ve developed respiratory mucous Ph buffer. 

Torpor is an important adaptation for microbats. It can range from a partial state of heterothermic arousal to full hibernation. Lowing body temperature reduces the need for food and fat storage.

A new study by University of California, Berkeley, researchers shows that bats’ brain activity is literally in sync when bats engage in social behaviors like grooming, fighting or sniffing each other.

Using scent markers and sound, mothers can locate their own babies out of thousands.

Life Span

10-20 years

Diet:

  • mosquitos
  • moths
  • beetles
  • dragonflies
  • flies
  • wasps
  • ants
  • grasshoppers
  • termites

Breeding

Photo Credit: Mnolf

Females can breed after 9 months of age, they congregate in maternity roosts.
Males become sexually mature at two years.
Gestation is about three months.
Generally, one pup is born per year. 
Young suckle for between four to seven weeks.
Mother’s must eat their body weight in insects to keep up with nursing demands.


Predators

  • owls
  • hawks
  • falcons

Roosts may come under predation from:

  • climbing animals
  • cats
  • coyote
  • raccoon
  • some species of snakes

Bat Species in Nevada County

  • Big Brown Bat, EPTESICUS FUSCUS
  • California Myotis, MYOTIS CALIFORNICUS
  • Canyon Bat, WESTERN PIPISTRELLE
  • Fringed Myotis, MYOTIS THYSANODES
  • Hoary Bat, LASIURUS CINEREUS
  • Little Brown Myotis, MYOTIS LUCIFUGUS
  • L0ng-eared Myotis, MYOTIS EVOTIS
  • Long-legged Myotis, MYOTIS VOLANS
  • Mexican Free-tail, TADARIDA BRASILIENSIS (migratory)
  • Pallid Bat, ANTROZOUS PALLIDUS
  • Silver-Haired Bat, LASIONYCTERIS NOCTIVAGANS
  • Western Red Bat, LASIURUS BLOSSEVILLII
  • Yuma Myotis, MYOTIS YUMANENSIS

White-Nose Syndrome

“WNS is considered one of the deadliest wildlife diseases, having killed over six million North American bats since it was discovered,” said CDFW Wildlife Veterinarian and Epidemiologist Dr. Deana Clifford. “WNS doesn’t affect human health or pets, but the ecological impacts of bat die-offs may indirectly impact agricultural systems through loss of the natural pesticide effect and nutrient cycling of bats.”

As of spring 2019, the California Department of Fish and Wildlife detected white-nose syndrome in bats in Chester, Plumas County.

Californians Can Help By:

Cavers/Spelunkers Can:

Click image to see more Life on the Creek art. Five dollars from every sale goes toward supporting the documentary project.

Resources:

California Department of  Fish and Wildlife – Deadly Bat Fungus Detected in California

Corkys Pest –Bat Identification 

Northern California Bats – Education, Lectures, Rescue & Resources

Sierra Club – A Song of Bats and Fire

Smithsonian Magazine – What is Killing the Bats?

UC, Berkeley – Bats Brains Sync when they Socialize

USGS – What is White-nose Syndrome?

Washington Post – The batty history of bats in the military and why this new idea just might work

White Nose Syndrom Response Team

Wikipedia – Bat

Wikipedia – Maternity colony

Wikipedia – Mexican Free-tail bat

 
 

AUSTIN, TX (May 8, 2019) – Bat Conservation International (BCI) announced today that early signs of the fungus Pseudogymnoascus destructans (Pd) have been detected at one of the world’s premier bat conservation sites, Bracken Cave Preserve.

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