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:

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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.

North American Beaver – Water Banker

History

In 1805, Lewis and Clark saw beaver dams “extending as far up those streams as [we] could discover them.” Even before the famous explorers, French trappers and traders were drawn to the land teeming with beaver.

The beaver is North America’s largest rodent. Its pelt is waterproof and has a double layer of insulation making it highly desirable for human use. At the height of pelt demand, some estimates claim that between 60-400 million animals were taken.

Fortunately, we have beavers living along Deer Creek!

The beaver method of water retention, stream restoration, and habitat rehabilitation.

Beaver ponds and dams;

  • reduce erosion
  • act as a fire break
  • slow water movement through a watershed, replenishing the water table, reducing the need for irrigation
  • filter nitrogen and other chemicals that cause algae blooms resulting in oxygen-deprived dead zones
  • retain sediments, increasing watershed biodiversity

Ponds volume keeps water temperatures cool, necessary for certain fish species

Discord Between Beavers and People

  • beaver may eat landscape plants and trees within 165 feet of the water’s edge
  • water pooling on the land will expand
  • roads and structures may flood
  • dams plug culverts and drains
  • animals and wildlife are attracted to the habitats beavers create

In 2017, the USDA Animal and Plant Health Inspection Service killed 81 beavers in California.

Beaver Problem Remediation

  • install a pond flow device, limiting water rise, eliminating flooding
  • choose landscape plants that beaver don’t eat
  • choose plants that resprout after a beaver visit
  • keep landscape plants distant from the water source

Barrier methods;

  • wrap large trees with 3 ft. high galvanized welded wire fencing or multiple layers of chicken wire
  • paint tree trunks with sanded paint ( mix 2/3 cup masonry sand per quart of latex paint)
  • surround groups of trees/ shrubs with 3 ft. high fencing strong enough to withstand a 60 lb animal pushing on it or attempting to  get under it
  • apply and reapply deer and big game repellent

Diet and Behavior

Nocturnal and non-hibernating, beavers eat plants; leaves, bark twigs, trees, willow, cottonwood and other deciduous trees. They’ll also eat garden plants if given the chance.

Pairs may mate for life but are not always monogamous. Kits are born between April and June, remaining with their parents for two years. A beaver colony usually consists of a breeding pair and several generations of their kits.

A full grown beaver can grow up to 60 pounds. (Fossil records show that they once reached 300 lbs!) Their lifespan in the wild is between 5 – 10 years.

Spending most of their time in the water, beavers have few predators. When on land, they are most vulnerable. Predators include; man, wolves, coyote, mountain lion, bears, bobcats, and dogs.

The Beaver Butt Thing – Castoreum

Aside from fur, trappers learned of another beaver special quality; castor glands, located near the anus, smell vanilla sweet. Castoreum is secreted with urine to mark territory. One can’t help imagining the very first gland discovery. A mountain man noticed it while taking the animal apart. To verify, he needed a close-and-personal secondary sensory test. Enthusiastic conversations between trappers spread the news and began a new industry.

Castoreum, a thick, syrup-like ooze was used in the perfume industry, starting in the 1800’s, to enhance other scents and increase their longevity.

“The United States, the Food and Drug Administration lists castoreum extract as a generally recognized safe (GRAS) food additive. … While it is mainly used in foods and beverages as part of a substitute vanilla flavor, it is less commonly used as a part of a raspberry or strawberry flavoring.” Wikipedia

Despite Castoreum’s listing with the FDA, it was never a substance in wide use. Anesthetizing and milking beavers was time-consuming and costly.

[Castoreum should not be confused with Castor, as in Castor Oil, which is a plant.]

Beaver Adaptations

  • continuously growing incisors
  • an insatiable need to build at the sound of water
  • tail functions as extra leg while on land
  • a mouth valve that keeps water out while carrying/floating a tree or branch
  • ear valves with the same function
  • back of throat valve – ditto
  • nostril valves – ditto
  • nictitating membrane covers eyes underwater acting like goggles
  • tail slaps on water warn of danger
  • hind foot has a split toenail used as a comb
  • fur is waterproof, treated with an oily substance
  • intestinal bacteria ferment cellulose to digest plant matter — this is why castoreum smells so good!

California Native & Aquatic Keystone Species

The National Geographic Society describes a keystone species as an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.

 

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If you liked this post, you may also like, Singing Coyote – the Ultimate Adaptor.

Resources:

Bay Nature – For beaver believers salvation lies in a once-reviled rodent

Beavers: 8 things to know about nature’s most impressive landscape engineers

Dispatch – USDA fights endless battle of wits with ingenious beavers

Bridge Creek (Oregon) Beaver Dam Analog Steelhead Restoration (2004-2020)

Climate Change | Beavers Help Battle Ongoing Drought

Eager Beaver author, Ben Goldfarb Radio Interview.

KCRA Beaver Problem

Martinez Beavers.org

Mental Floss – A Brief History of Castoreum, the Beaver Butt Secretion Used as Flavoring

Nature World News – (Beaver) Dams Help Remove Nitrogen From Estuaries and Restore Streams | 2015

National Geographic – Beaver Butts Emit Goo Used for Vanilla Flavoring

National Geographic – Beavers Have Vanilla-Scented Butts and More Odd Facts

National Geographic – Beavers —Once Nearly Extinct—Could Help Fight Climate Change

National Park Service – Beaver

New York Post – Distillery has new bourbon flavored by beaver secretion

New York Times |2017 – Beavers Emerge as Gents of Arctic Destruction

NOAA Fisheries – Working with Beaver to Restore Salmon Habitat

NOAA – Working with Beaver to Restore Salmon Habitat

Science Magazine | 6/7/18 – Beaver dams without beavers? Artificial logjams are a popular but controversial restoration tool – rebeavering Bear Valley (an hour north of Redding)

Smithsonian’s National Zoo – Beaver

Spokane Lands Council – Beaver Solution

Time Magazine – The True History Behind Idaho’s Parachuting Beavers

USDA – 2017 California Animals Killed Report

USDA – How to Keep Beavers from Plugging Culverts [PDF]

USDA – Mountain Beaver Damage and Management

Washington Dept. Fish and Wildlife  – Beavers

Wikipedia – Beaver in the Sierra Nevada

Wikipedia – California Fur Rush

 

 

 

 

 

 

Warning! Video below shows animal butchering – Beaver Castor Gland Removal

 

 

 

 

 

 

 

 

 

 

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