Oct. 25, 2019 – October 24-31 is Bat Week, an annual international celebration of these fascinating winged mammals and the important role they play in our environment.

California is home to 25 species of bats, ranging from the commonly found Mexican free-tailed bat, a medium-sized bat that makes its home in caves, attics, under bridges and in abandoned structures, and canyon bat, smallest of California’s bats with a wingspan of about seven inches, to the western mastiff bat, which has a wingspan of almost two feet.
Bats – which are the only mammals that can fly – can be found in just about every corner of California. They serve several hugely important functions, including pest management, pollination of rare plants and seed dispersal.
About two-thirds of bats are insectivorous. Each night, a bat will consume between 50 and 100 percent of its own weight in insects. They protect our food crops and timber industry – worth more than $57 billion per year – and if it weren’t for bats, farmers might need to use far more chemical pesticides than they do now. Nationwide, the service bats provide to American agriculture by suppressing insect populations has been valued at an estimated $4 billion to $50 billion per year.
Unfortunately, population declines have caused 17 of California’s 25 native bat species to receive some level of state or federal protection. And the threat is only increasing.
California Department of Fish and Wildlife (CDFW) biologists are preparing for the possibility of the introduction of a fungus known to be deadly to bats. In June 2019, the fungus that causes White-nose Syndrome (WNS) was detected in low levels for the first time in Plumas County. The fungus – Pseudogymnoascus destructans – grows in and on bats’ skin during winter hibernation and spreads quickly through bat colonies. WNS has killed more than six million bats elsewhere in the U.S. and minimizing its impacts on California’s bats is a top priority for CDFW’s Nongame Wildlife Program.
“Given the huge impact WNS has had on eastern populations of bats, and its occurrence now in Washington state, it is essential to be vigilant for signs of an outbreak of the disease in California so we can take appropriate action, when needed,” says Scott Osborn, CDFW’s lead for WNS response.
Californians can learn more about WNS, including how to report bats that could be suffering from the disease, on CDFW’s website.
In addition to reporting bats that might be suffering from WNS, other ideas to promote bat conservation can be found on the Bat Week 2019 website. For example:
  • You can report bat sightings using the North American Bat Tracker, and help biologists document the location and health of existing bat colonies.
  • You can take an urban bat walk in many communities. Contact your local nature center, museum, zoo or other educational institution to see if a bat expert is available to lead a walk.
  • You can build a bat house for your own yard, helping to promote a healthy environment in your own backyard.
  • You can plant a bat-friendly garden that attracts night pollinators, like moths, that bats like to eat.
“In addition to the important ecosystem functions they provide, bats are simply amazing animals,” says Osborn. “They occupy a completely unique niche among animals: they fly, they use echolocation to navigate at night and capture insects in complete darkness, and many hibernate to escape the harsh conditions of winter when their insect prey is unavailable. When you consider all these adaptations are packaged in an animal that weighs about as much as a nickel, you can’t help but feel a sense of awe.”

When you file your California income tax return, please consider making a voluntary contribution to the California Sea Otter Fund (line 410) or the Rare and Endangered Species Fund (line 403). Thank you!