In the growing darkness, a tiny shape swoops down, barely missing my hair, and scoops up a drink from the river while still in flight. Long after the last birds have gone to roost, a member of one of our 19 local species of bats is beginning its nightly prowl.
Bats have an undeserved reputation as dirty or frightening creatures. While popular culture may associate bats with vampires, disease, or Gotham City crime fighters, they are generally innocuous to humans. A bat may fly low, just over your head chasing evasive insects but it is in complete control; bats do not attack humans. Only three bat species—all of which live in South and Central America and the Caribbean—feed on blood. The virus that causes COVID-19 has not been detected in any of the 47 species of bats found in the US. And though bats, like other mammals can carry rabies, California's last reported case of human rabies was in 2012.
Bats, Order Chiroptera (Greek, hand wing), comprise 22% of all mammal species on Earth. Analogous to human fingers, their forelimbs have evolved into wings; they are the only mammals adapted for sustained flight. Bats use echolocation to find food and navigate in the dark. They emit high-frequency sonic pulses by passing bursts of air over their vocal cords and listening for the returning echoes. The sounds are so piercing that the bat's middle ear bones momentarily disconnect to prevent self-deafening.
Voracious insectivores, bats play an important role in pest control. Especially useful around our local vineyards, one little brown bat can eat its body weight in insects every night, substantially saving pesticide usage. After their nocturnal foraging, they return to the same roosting sites, favoring dead or dying trees, caves, and crevices. Or sometimes old buildings like Hesperia Hall.
Scientists who study bats, chiropterologists, favor the shorthand LBBs for the numerous Little Brown Bats that are difficult to identify in flight. Since each species of bats has its own unique sonic signature, analysis done using an ultrasonic data collector is the current method of classification. The Echo Meter Touch 2 PRO made by Wildlife Acoustics loads onto a cell phone and picks up bat echolocation sounds, identifying the probable species. My sporadic success using plant identifiers on my phone leaves me hesitant to cough up the $179 but it might make a nice birthday gift for a chiropterophillic friend.
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