The only known habitat for two of Kauai’s strangest endangered animals recently received critical habitat designation from the U.S. Fish and Wildlife Service. The eyeless wolf spider and one of its prey, a shrimp-like eyeless amphipod, both live deep inside the dark, damp caves of Kauai’s Koloa District, and nowhere else in the world. Yet the size of the area covered by the designation was reduced by 94 percent after private landowners told the agency that the original proposal could have cost them millions of dollars.
The final critical habitat rule includes 272 acres of southern Kauai in a highly developable resort area. This is only a fraction of the 4,193-acre critical habitat initially proposed in March 2002.
A draft economic analysis found that private landowners could face significant economic impacts due to the critical habitat designation. In the final rule, the direct economic costs were said to be between $260,000 and $429,000 over 18 years. The potential indirect costs, mainly due to loss of development potential and associated property values, is estimated at between $4.5 million and $6.1 million over 18 years.
“I want to thank the private landowners in the area who shared so much new information with us,” said Paul Henson, field supervisor for the Pacific Islands Fish and Wildlife Office, in a press release. “Due to their assistance, we have a much better knowledge base about these two cave species and their habitats, and we were able to better refine the critical habitat rule.”
During the review of the new rule, promising new information about the two endangered species was also brought to the attention of the scientists. They found that the Kauai cave wolf spider inhabits two more caves than was originally thought, bringing their total known occurrence to six caves in the Koloa area. They also found one additional cave inhabited by the cave amphipod, bringing that species total to seven occupied caves.
“During the public comment period for the proposed rule, we were provided with a significant amount of new scientific information regarding site-specific conditions on lands that were part of the proposed critical habitat,” Henson said. “Based on this information and our field visits, we were able to eliminate areas that do not provide the habitat needed by these cave animals or are not essential for their conservation.”
Photographs, drilling records and archaeological and biological surveys were also made available to the Service, which helped eliminate areas from the final critical habitat designation because they did not provide the habitat needed by the two invertebrates.
“We know that areas with more than 12 inches of soil deposits generally are unsuitable because the soil tends to fill the caves and mesocaves where the animals live,” Henson explained in the release.
The Kauai cave wolf spider and the Kauai cave amphipod are both “troglobites,” which means that they need a cave environment to survive. To provide the right habitat for these unique species, the caves must have near 100 percent relative humidity and food sources for the animals. The lava tubes of the Koloa of Kauai can provide this environment. On many areas of the island, lave tube caves have either collapsed of filled with sediments, but the Koloa area contains some younger lave flows that include caves, cracks and caverns that suit the cave creatures.
The Kauai cave wolf spider is only about 1.5 inches long. It is a hunting spider that has lost its eyes through the process of evolution. They have adapted to live in the lava tube caves, where eyes are useless in the absolute darkness. The spider chases and grabs its prey, instead of building webs. The Kauai wolf spider, unlike most wolf spiders, produces only 15 to 30 eggs per clutch. The large newly hatched spiderlings are carried on the female’s back for only a few days.
The Kauai cave amphipod is 0.25 to 0.4 inches long and is a pale landhopper that resembles a shrimp and has also lost it eyes. The amphipod is believed to be an important food source for the Kauai cave spider. It feeds on the decaying roots of surface plants that reach into the cave, along with rotting branches and other plant materials.
Critical habitat refers to specific geographic areas that are essential for the conservation of a threatened or endangered species and that may require special management considerations. These areas do not have to be occupied by the species at the time of designation. A designation does not set up a preserve or refuge, and only applies to situations where Federal funding or a Federal permit is involved.
The final critical habitat rule, including maps and a detailed description of the units, was published in the April 9 edition of the Federal Register, and is also available at the U.S. Fish and Wildlife Service website. Copies of the rule may also be obtained by calling the Fish and Wildlife Service’s Honolulu office at 808-541-3441. The rule takes effect in about a month.