Hawaiian Hoary Bat
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Kihei Iki |
DISTRIBUTION and HABITAT:
The Hawaiian Hoary Bat (Lasiurus cinereus semotus) is a member of the Family Vespertilionidae (Common or Vesper bats). It is described as a subspecies of the North American Hoary Bat. Hoary means frosted, and refers to the white tips of the body hairs.
Native Hawaiians named the bat Opeapea, referring to the bats half-taro leaf, canoe sail, cross, or radially spoked outline. Bats are still commonly seen on the islands of Hawaii, Kauai, and Maui, but are rarely seen on Oahu. The bat is considered to be Hawaiis only native land mammal. There is fossil evidence of at least one other Hawaiian bat species. Several failed attempts at deliberate introduction of non-native bat species have been reported.
BEHAVIOR:
Usually considered solitary, Hawaiian bats are assumed to roost in trees and have only rarely been seen exiting lava tubes, leaving cracks in rock walls, or hanging from man made structures. They are found in both wet and dry areas, and from sea level to 13,000 ft.
DIET:
Hawaiian bats forage for flying insects, primarily in the early evening hours. Typically it feeds over streams, bays, or along the seacoast. Others are seen feeding at the junction of forests and open pastures, or over lava flows. Bats can be attracted to insects congregating near bright floodlights. As do most insectivorous bats, Hawaiian bats emit high frequency (ultrasonic) echolocation calls that detect their flying prey. Hawaiian hoary bat echolocation calls have been measured to peak at 27.8 KHz, but range from 15 30 KHz. Their lower frequency social calls may be audible to humans. These low frequency chirps are used to warn other bats away from their feeding territory.
Hoary bats can probably eat up to 40% of their own body weight in a single meal. It has been suggested that certain moths in Hawaii have evolved with the bat and can detect the social calls of hoary bats. Upon hearing the bats, the flying moths will defensively dive to elude the hunting bats. The Hawaiian hoary bat is known to feed on termites, mosquitoes, moths, beetles, flies, crickets, and stink bugs.
ENDANGERED STATUS:
The US Fish and Wildlife Service and the State of Hawaii have classified it as an endangered species since the mid nineteen seventies.
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Kihei Ha ehu ehu |
ZOO HISTORY:
In December of 1991, an injured bat was found at a nursery in Kihei, along the coast of Maui. Turned in to the State Department of Agriculture, this bat was transferred to the Honolulu Zoo for long-term care. The bat was determined to be an adult female and it had sustained a fracture of its left wrist. Conservative treatment was started and the injury healed without complications, however the wrist joint became fused in the flexed position. Unable to extend the left wing, the bat could not fly.
An inadequate diet was thought to be the greatest obstacle to long-term maintenance of an insectivorous bat, so several experts were consulted and various diets were tried. The bat was named Kihei iki which means little cloak or shawl. She was housed at the zoos Animal Health Center until her death in September 1994. The longevity of hoary bats is unknown; it is assumed that they have a relatively short life span of about 6 7 years.
On August 16, 2002, another injured female bat was recovered at Burlas Farm in Kaloko, Kona, on the Big Island of Hawaii (elevation 1,600 ft). The Burlas Jack Russell Terrier, Ipo, found the bat in their yard. Wildlife rehabilitator Ann Goody at Three Ring Ranch cared for the bat until it was determined that its injuries were too severe to allow the bat to be released back into the wild. The bat was then transferred to the Honolulu Zoo in early November 2002. Coincidentally, this bats injury was located at the same site, the left wrist joint, as the previous bat.
There were key differences however, as this bat appeared to be quite young, perhaps only a few months old. Also, its hair coat pattern was very different from the classic hoary color. This young bats coat color pattern was uniformly reddish brown. Perhaps it is an example of what has previously been described as the red phase of the Hawaiian Hoary bat. She has been named Kihei Ha ehu ehu, meaning reddish brown cloak, and is being housed again at the zoos Animal Health Center.
Ehu's diet consists entirely of mealworms, which are raised on a special high calcium cricket diet with sliced apples as their water source. She will not be on public display, but may be viewed at the Animal Health Center for specific research or educational purposes.
Update:
On the morning of February 1, 2008, our Hawaiian bat Ehu was found dead. Over the previous couple of weeks she had been losing hair and slowing down in her activity and appetite. Patchy hair loss was also observed in our previous bat Kihei and may be indicative of a dietary or nutrient deficiency. Ehu was found in a sleeping position on the padded floor of her enclosure and seems to have passed peacefully.
Kihei lived with us for just short of 3 years and we were able to care for Ehu for over 5 years. The average life span of Hoary bats is unknown, and although bat experts think they might not live more than 6 to 7 years in the wild, a bat rehabilitator in California kept one of the mainland subspecies of hoary bat alive for about 8 years.
We learned much from Ehu over 5 years, such as documenting a change in her coat color pattern from a generalized reddish-brown to the classic hoary pattern. It also appears that she showed a consistent body weight gain during the winter months (based on daily body weight measurements). Although we have only been exposed to two individual Hawaiian bats, the combined 8 years of experience with them shows them to be very docile and gentle creatures. They would literally fall asleep in your palm after feeding and with gently stroking of their heads.
Federally funded research of the Hawaiian bat continues on the Big Island of Hawaii yet there is still much unknown about this enigmatic but increasingly charismatic native Hawaiian mammal. We will always be grateful for every opportunity to be exposed to these remarkable animals.
Note: The above comments are by our Zoo Veterinarian, Dr. Ben Okimoto.
References:
Bat Conservation International, Dr. Merlin Tuttle
Mammals In Hawaii, Dr. P. Quentin Tomich
