Batty About Bats...and a Free Webinar Oct 12! | UC Agriculture and Natural Resources

October 3rd, 2022

Throughout history bats have been objects of fear, hostility, and myths, largely due to their nocturnal, mysterious behavior. Horror movies and media exaggerations has led people to believe they are dangerous disease-ridden blood suckers. The truth is very different.

Fascinating Bat Bits

Bats are the only true flying mammal, making up a quarter of the world's mammals. There are 1,100 species of bats, with forty species in the USA. California has twenty-five species, most of which are insectivores.

Bats are one of only three mammals that generally sleep upside down, with sloths and manatees being the other two.

Brown bat hovers over a cluster of flowers. — Bat pollinating agave flower, Merlin D. Tuttle.

Bats can live between five and thirty years, depending on the species. Most female bats have only one pup per year, making them vulnerable to extinction.

According to the U.S. Forest Service, fruit-eating bats are responsible for dispersing seeds that grow into bananas, avocados and 300 other plant species around the world. Agave plants (which are the source of tequila and mezcal) evolved to supply most of their nectar after dark to attract the nocturnal bats to cross-pollinate their flowers.

Insect eating bats often consume their own weight in insects each night, eating up to a thousand mosquito-size insects in an hour! It is estimated that bats' value to agriculture could exceed $23 million per year.

Bats are excellent fliers with some species flying up to 60-100 mph. They can locate and catch insects in midflight in total darkness, using echolocation, which is the ability to locate objects by reflected sound waves.

Where Do Bats Live?

Small bats grouped together. — Pallid bat colony, Merlin D. Tuttle

Bat roosting sites include caves, tree cavities, buildings, bridges, attics, barns, bat boxes or other structures.

Usually, males and females with young will roost separately, but in late summer or early autumn, males may join the colony. In the winter when insects become scarce, some bats hibernate, while others may migrate to warmer areas, returning in the spring months.

Bat Myths and Facts

Because of their nocturnal habits, bats are rarely seen, so seem mysterious and are often misunderstood.

Myth - Bats suck people's blood.

Two adult bats hanging from roof truss, Jack Kelly Clark.

Fact - There are three species of “vampire bats” whose food source is blood. None are found in the USA.

Myth - Bats are blind.

Fact - Bats do have small eyes, but they are functional. Megabats, which are larger bats such as fruit bats (found in forests of Africa, Asia, Australia, and Europe), search for their food using both sight and smell.

Myth - Bats fly towards and get tangled in people's hair.

Fact - Bats hang upside down from their roosts and tend to drop down and flap their wings before they start to lift off in flight. So, though it may appear the animals are swooping down on you and want to nest in your hair, they're not. In fact, bats don't make nests.

Bats as Pests

Like many mammals, bats can contract rabies. It is rare for a rabid bat to bite a human. According to the World Health Organization, an estimated 59,000 humans die from rabies each year, with 99% of these deaths being due to contact with rabid, unvaccinated dogs.

Most bat parasites such as fleas and mites are host specific and cannot survive on other animals. No evidence exists of disease transmission to humans or domestic pets from bat parasites.

Bat droppings, known as guano, can harbor a widespread fungus found in soil, Histoplasma capsulatum, which causes Histoplasmosis in humans. However, most human infections come from birds.

If You Find a Bat. . .

Leather glove holding a bat. — Pallid bat peers out of gloved hand, Kathy Keatley Garvey.

A bat that flies into your living space is usually lost, perhaps young, and its only goal is to find an exit outside. While keeping it in sight, close all the interior doors to the room, opening exterior doors and windows to provide means for the bat to escape.

If you find a bat laying on the ground, please leave it alone, especially in the spring or fall, when they may be migrating and are just resting during their long journey. If after an hour or two, the bat has not moved, it is likely sick and should be avoided. If it is in an area where children or pets can access it, you may want to trap it. While wearing leather gloves, carefully put a box over it and slide a piece of cardboard underneath it to trap it. Then contact your local wildlife rescue organization (in Stanislaus County that is the Stanislaus Wildlife Care Center at 1220 Geer Rd., Hughson, 209-883-9414).

Bats in Trouble

Bat with wings outstretched against the night sky. — Mexican free tail bat in flight, Merlin D. Tuttle.

More than half of the bat species in the United States are in severe decline or listed as endangered. In addition to loss of habitat, tree-roosting and migratory bats face significant threats from wind turbines.

One of their most dire threats comes from white-nose syndrome (WNS), a disease that has decimated bats in the USA and Canada. Bats that hibernate during the winter do so to ration their energy and survive during a time of year when insects are scarce. The WNS fungus grows on bats' skin which disturbs their hibernation, thus increasing the amount of energy they are using, resulting in dehydration, starvation and often, death. However, a 2015 breakthrough appears promising. A team of researchers treated infected bats infected with a common bacterium on bananas which seems to stop the growth of the fungus. The treated bats were successfully released back to the wild.

How Can You Help Bats

Smiling advisor holding wooden bat box to show audience. — Farm Advisor Rachael Long shows a bat house, UCANR.

Bats are a part of healthy and diverse ecosystems. Some ways you can help:

Learn more about bats, educating friends and family.
With an iNaturalist app on your smartphone, you can take part in citizen science by observing bats in a park or your own backyard.
Build a bat house. Bats need places to roost, rest, raise young. UC IPM gives information how to build a backyard bat house: http://ipm.ucanr.edu/PMG/PESTNOTES/pn74150.html. Other bat house links are provided in Resources. Choose a pesticide-free open location with five to seven hours of sunlight. Bats prefer interior temperatures of 80-100ºF during the summer.
Stay out of caves when directed. Bats need to be undisturbed in caves, particularly in the winter months. If you do visit caves where bats live, clean your shoes before and after to avoid tracking white nose syndrome to another cave.

Where to Go See Bats

A dozen bats leaving the Yolo Causeway bridge and flying together to look for food. — Mexican free-tailed bats leaving the Yolo Causeway at dusk, Kathy Keatley Garvey.

There are a couple locations near Stanislaus County where you can go see bats at dusk during the warmer months:

Yolo Bypass Wildlife Area: Not far from Sacramento, this colony resides under the Yolo Causeways, a 3-mile-viaduct on Interstate 80. These are Mexican Free-tailed bats (Tadarida brasiliensis) who take up residence in the crevices in the concrete bridge. The colony numbers up to a quarter-million bats in size. If you want to see the bats yourself, you can find a place with a good view, but you can also book tours that are specifically designed to get you close enough to see the colony. https://www.yolobasin.org/bats2022/
Consumnes River Preserve: Near Lodi, several species of bats are found in both the riparian forest and in a bat-friendly bridge built over the Cosumnes River. https://www.nature.org/en-us/get-involved/how-to-help/places-we-protect/cosumnes-river/

All About Bats Webinar

Bat with wings spread in flight with a bright green grasshopper in its mouth. — Pallid bat with grasshopper, Merlin D. Tuttle

If you wish to learn more about these vital, fascinating creatures, join Rachael Long, UC ANR Integrated Pest Management Advisor for Yolo, Solano, and Sacramento Counties for her webinar “All About Bats.” Rachael will discuss the natural history of bats, including common types found in California, bats and pest control, bat boxes to attract bats, excluding unwanted bats, bats and rabies prevention, as well as fielding questions from participants about bats. Listed below is registration information:

Webinar: “All About Bats”
Where: On Zoom
When: Wednesday, October 12, 2022, from 1:00-2:30 p.m
Instructor: Rachael Long, UC ANR Integrated Pest Management for Yolo, Solano and Sacramento Counties
Cost: Free
Register: https://ucanr.edu/all/about/bats