The Organization for Bat Conservation has declared the week from Oct. 25 through 31 as Bat Week. They’re encouraging folks on the mainland to build as many bat houses as possible on Halloween. Though we don’t have a site for this bat house building marathon in Hawaii, we can all participate in Bat Week by reviewing the importance of bats to us and our environment.
In Hawaii, we have a single species of bat. The Hawaiian hoary bat (Lasiurus cinereus semotus) has the Hawaiian name opeapea. This bat is the only Hawaiian endemic land mammal. The only other endemic mammal is the Hawaiian monk seal. The opeapea arrived here many thousands of years ago. Its distant relatives probably made the 2,500 mile journey from the North American mainland with the help of a storm or a floating tree at least 10,000 years ago.
Hawaiian hoary bats are small creatures. Though they have a wing span up to 13 inches, most of them weigh only half an ounce. They are usually solitary individuals that roost in trees and make nightly forays to feed on moths and other insects. Their name refers to the frosty white tips on their fur, which is a reddish brown color.
Most bats, including the opeapea, have prominent ears compared to their body size. These help them maneuver in flight using echolocation. This bio sonar makes it possible for them to locate objects by reflected sound. They make a sound with their vocal cords that is not audible to humans. The sound bounces off objects including their insect prey, allowing them to find food and avoid objects that are difficult to see at night.
The hoary bat was the first mammal to arrive in Hawaii and is still here today, basically unchanged. At this point, this tiny friend to farmers and gardeners is on Hawaii’s endangered species list with only about 1,000 remaining. Since these flying mammals offer invaluable services and are an important player in our fragile ecosystem, it is in our interest to see that they survive and thrive.
In their nightly flights, these bats eat nearly their body weight in insects including mosquitoes. Where the bats are numerous, insect populations are greatly reduced. Many bat species function as pollinators. Our hoary bat’s diet is mainly insects but they certainly come in contact with plants and their flowers in their nocturnal activities, as well as during their daily resting and roosting. Though bats in general have a scary reputation, our hoary bats are tiny, cute, helpful and quite harmless.
Legislation to assign the opeapea the land mammal title for the state is in process. Bat Conservation International is encouraging the designation. Members believe that highlighting this unique and valuable animal in this way would increase understanding and appreciation for the local hoary bat.
Though loss of habitat because of development is the major reason for bat numbers to decline, several other issues are affecting the bat population. The use of pesticides and the increase in predatory animals, including cats and rats, both play a part in bat decline. Roost disturbance because of a reduction in tree cover is also a factor.
Conservation efforts are seeking to help our bats thrive. As early as 1970, the Hawaiian hoary bat was listed as a federal and state endangered species. Both a recovery plan and conservation strategy recommend conserving known habitats and managing forests as well as agricultural lands to support existent bat populations. Educating the public about the bat and its many benefits is also an important step toward increasing bat numbers.
We can all help support bats. We can watch for them gliding through the twilight right after sunset and help conserve areas near the sightings that might provide roosting and daytime rest areas for them. We can spread the positive word about bats, discourage people’s fears and share information about the help they offer in reducing insect populations. We can preserve trees and forested areas on our land to encourage bats and to help maintain existent populations.
Check out information on the web about Bat Week and about our wonderful native hoary bat. A video of a release of an injured bat after healing is available at www.threeringranch.org. An excellent article by Greg Koob, Farmers Can Help our Hawaiian Hoary Bats is available at http://www.ctahr.hawaii.edu/sustainag/news/articles/V11-Koob-hoarybat.pdf. Check these out and tell others to do so. Together we can help this little critter survive.
Tropical gardening helpline
Carole asks: Why haven’t you written about the importance of bats in tropical gardening? When and if you do, please include instructions for building a bat house. We all need to encourage bats onto our property and offer protection to these valuable animals.
Answer: Thanks for the encouragement to write about bats. The Hawaiian hoary bat is a solitary species that roosts in trees or shrubs, where it can rest hidden in foliage and have a clear flight line. They usually stay away from people and their activities. They do not use bat houses.
Building a bat house is a wonderful activity, however, for children and adults. Consider using the online instructions for building a bat house at http://batweek.org/index.php/resources/how-to-make-a-bat-house or go to http://batconservation.org/help/bat-houses and download the e-guide to building and installing bat houses. Check out YouTube sites if you want to see how others have constructed and placed bat houses.
Register with Bat Conservation International and send the bat house as a gift to a friend on the mainland who lives in an area where the house will be used.
Meanwhile, help spread the word about our Hawaiian hoary bat as a way to celebrate Bat Week.
Email plant questions to konamg@ctahr.hawaii.edu for answers by certified master gardeners. Some questions will be chosen for inclusion in this column.
Diana Duff is a plant adviser, educator and consultant living on an organic farm in Captain Cook.
Gardening events
Saturday: Coffee Farm & Mill Improvement meets from 3 to 5 p.m. at the Kona Cooperative Extension office in Kainaliu with Fernando Vicentini, a mechanical engineer from Brazil, speaking on improving efficiency to lower costs and help control coffee berry borer and other pests. Call Gina at 322-4892 to reserve a spot or email ginab@hawaii.edu by Friday.
Farmers markets
Wednesday: Hooulu Farmers Market, 9 a.m. to 2 p.m. at the Sheraton Kona Resort & Spa at Keauhou Bay
Wednesday: Sunset Farmers Market, 2 p.m. to sunset at the north makai corner of the Kmart parking lot
Saturday: Keauhou Farmers Market, 8 a.m. to noon at Keauhou Shopping Center
Sunday: South Kona Green Market, 9 a.m. to 2 p.m. at Amy B. H. Greenwell Ethnobotanical Garden in Captain Cook
Monday to Saturday: U-Pick greens and produce, 10 a.m. to 4 p.m. Tropical Edibles Nursery in Captain Cook
Plant advice lines
Anytime: konamg@ctahr.hawaii.edu
Thursday: 9 a.m. to noon at UH Cooperative Extension Service in Kainaliu, 322-4892.
Monday, Tuesday and Friday: 9 a.m. to noon at UH CES at Komohana in Hilo, 981-5199 or himga@hawaii.edu.