It’s California Bat Week October 24-31, 2018.
Bats are one of the most important animals in our environment. With more than 1,300 different species in the world, bats are diverse in both how they look and how they keep ecosystems balanced.
While they might be creepy, bats are vital to a healthy environment. One bat eats thousands of insects every night, benefiting crops, forests, and humans. Fewer insects mean less need for pesticides. It’s been estimated that bats save US farmers $3.7 billion worth of insect control each year.
Like bees, bats assist in pollination. They help disperse seeds by munching on fruits and dropping seeds the natural way (read: guano), in forests. Fruit bats contribute to the pollination and seed dispersal of some of our favorite foods, such as bananas, avocados, pineapples, figs, and mangoes. They even help in the production of tequila (agave) and chocolate. Bat guano is used as a powerful fertilizer worldwide and vampire bats have created anti-clotting medication to help stroke victims.
Today, bat populations are in decline everywhere due to habitat loss, pesticide use, destruction of roost sites, climate change, disease, and other threats.
Development of open space to suburban, commercial, and even agricultural use has threatened the natural habitat of bats. While some may prefer the attic of your grandmother’s house or barn, others prefer mines, caves, and trees near rivers and streams. Loss of habitat has pushed some species of these beneficial creatures to the brink of extinction.
The Department of Conservation’s Division of Mine Reclamation assists in the protection of bat habitat through its Abandoned Mine Lands Unit (AMLU). The main mission of AMLU is to identify and remediate dangerous mine openings and other hazards left when historic mining operations ceased – even as far back as the Gold Rush era of the mid-1800s. When bat habitat is found in old abandoned mines, AMLU can seal them in such a way that humans are kept out for their own safety while critters such as bats continue to have access.
“Bat gates are typically installed in mines that are hazardous to human visitors but also provide valuable bat habitat,” said AMLU’s Jon Mistchenko.
AMLU staff works on a variety of remediations of legacy abandoned mine sites in California in partnership with multiple landowning agencies, such as the California State Lands Commission, California Department of Parks and Recreation, California Department of Fish and Wildlife, National Park Service, US Bureau of Land Management, and US Forest Service. Staff receive special training, including from the US Mine Safety and Health Administration, wear proper safety equipment, and work in teams of at least two persons, before approaching or entering any abandoned mine.
“Abandoned mine sites can be an irresistible and sometimes deadly draw for children and adults. Our recommendation to the general public is to ‘Stay Out, Stay Alive,’” cautioned AMLU Program Manager Cy Oggins.
An initial inspection of each site is required, sometimes involving underground entry to assess physical hazards, wildlife potential, and to determine appropriate closure methods. Bats are often the focus of these underground biological assessments because while some bats live under bridges, in buildings, and trees, other species live only underground. Protecting this subterranean habitat is critical to the survival of bats, and AMLU staff takes great care to ensure that happens.
Recently, on a hot summer day in the Mojave Desert, as AMLU staff inspected an underground abandoned mine, they encountered more than they expected.
“During the hot season, much of the desert wildlife spend daylight hours underground. We found rattlesnakes, desert tortoises, rats, and bee honeycombs underground,” said Mistchenko.
The occasional solitary bat was photographed on this inspection, but once AMLU staff encountered a bat maternity colony, immediate exit was required.
A maternity colony is a temporary group of female bats, often found in warmer mines, gathered together to give birth, nurse, and wean their pups. Bats are mammals, like humans, and typically give birth to one pup at a time. The pups grow very rapidly and learn to fly and hunt during this time, but these groups can be very sensitive to disturbance. Once the pups are weaned, they leave the colony and the colony itself will break apart. Maternity colonies vary by species and can range in size from 10 or fewer bats to over 15 million at a time.
“One abandoned mine we inspected included a side tunnel with a very tight bend; moving slowing and carefully around the bend, my headlamp suddenly illuminated 20 pairs of eyes staring back at me—a maternity colony hanging just 15 feet in front of me,” recounts Mistchenko. “I quickly backed around the corner so that they would not feel threatened by my presence—unfortunately resulting in no photos of the colony. Even when expecting it, encountering wild animals while in a dark, confined space is always a bit surprising to me.”
With the important benefits bats provide, it’s crucial to protect them and honor this natural ecosystem. Take a look at some of AMLU’s work here in this short video:
More photos of recent mine inspections below.
Learn more about bats through these resources:
Bat Appreciation Day – April 17