Kanab Ambersnail

Oxyloma haydeni ssp. kanabensis

Description

The Kanab ambersnail is a small terrestrial snail about 0.5 to 0.8 in (14 to 19 mm) long. The mottled, grayish to yellowish amber shell has three or four whorls in an elongated spire and a broad, expanded aperture. The snail's eyes are borne on the ends of long stalks; the tentacles are small protuberances at the base of the eyestalks.

This species has also been known as Succinea hawokinsi. Some specialists believe that the current taxonomic status of the snail should be reevaluated to determine whether it deserves classification as a full species.

Behavior

Almost nothing is known about the specific behavior of the Kanab ambersnail. Other members of the genus feed on microscopic plants and lay about a dozen jelly-like eggs at the base of plants. The eggs hatch after two or three weeks. Young snails reach full size after about two years, and die soon after.

Habitat

The Kanab ambersnail lives in marshes that are constantly watered by springs and seeps at the base of sandstone cliffs. It is found in close association with cattail (Typha domingensis) which it uses as vegetative cover and protection from predation by birds. It is always associated with perennially wet soils and has never been found in drier habitats, or even in places which are attractive to other land snails, such as underneath logs.

Distribution

This snail species was first collected in 1909 from an area known as The Greens, on Kanab Wash, six mi (9.6 km) above Kanab, Utah. It has only been found at two locations in Kane County in extreme southern Utah, and one in Grand Canyon, Arizona. In Arizona, surveys of 81 springs near Vaseys Paradise failed to find any Kanab ambersnails. However, in 1995, a small population of the nominate subspecies O. h. haydeni was found at Grand Canyon National Park's Indian Gardens Campground.

The two known Utah populations of the Kanab ambersnail are just over a mile apart on privately owned land. A colony inhabiting a marsh beneath a cliff in Kanab Creek Canyon has almost vanished. Although once common at this site, the snail population has suffered a dramatic crash. An intensive search in 1990 found only three individuals. The wetland habitat at this site was recently altered by draining much of the water to provide for domestic livestock.

The only remaining large population occurs in marshes in Three Lakes Canyon, a tributary drainage of Kanab Creek, about 6 mi (9.6 km) north-west of Kanab. In June 1990, the Kanab ambersnail population was estimated at 100,000. However, soon afterward, the landowner began modifying the marshes in preparation for development. This resulted in the destruction of a portion of the snail population.

Threats

The possible imminent destruction of the only remaining substantial Kanab ambersnail population moved the U. S. Fish and Wildlife Service (FWS) to list the snail as Endangered on an emergency basis on August 8, 1991. This emergency determination was scheduled to expire on April 3, 1992. During this eight-month period the FWS followed its normal process in proposing the species for listing. The final listing was done on April 17, 1992. A recovery plan was published in 1995.

Although private landowners had indicated a willingness to protect the snail and negotiate the sale of the property to the federal government or The Nature Conservancy, they were still considering development of the property as a retirement home or recreational vehicle park and campground. The fact that development of the property could happen before a regular listing proposal could be finalized prompted both the emergency and final listings. Discussions are continuing between the landowners and The Nature Conservancy for sale of the property.

Conservation and Recovery

In 1995, FWS released a recovery plan for the Kanab ambersnail. The criteria for downlisting the rare mollusk are to maintain at least 10 populations large enough to ensure their long-term viability, and to establish compatible habitat management practices. These objectives are to be achieved by the following actions: control of threatening activities, such as the timing and hydrological characteristics of water releases from the Glen Canyon Dam; acquire and restore the habitat of the Three Lakes Population, as well as other suitable habitats; conduct surveys to find appropriate habitats for reestablishment attempts; conduct research into the biology and ecological needs of the Kanab ambersnail; establish new populations in suitable habitat, using stock from a captive-rearing program; and implement a program of public education, to build support for the conservation of the endangered snail. The known, privately owned habitat of the Kanab ambersnail will have to be protected. This can be achieved by acquiring the land and establishing a protected area, or by negotiating conservation easements.

Contacts

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 1306
Albuquerque, New Mexico 87103-1306
Telephone: (505) 248-6915
Fax: (505) 248-6915
http://southwest.fws.gov/

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P.O. Box 25486
Denver Federal Center
Denver, Colorado 80225
Telephone: (303) 236-7920
Fax: (303) 236-8295

Utah Ecological Services Field Office
145 East 1300 South, Suite 404
Salt Lake City, Utah 84115-6110
Telephone: (801) 524-5009
Fax: (801) 524-5021

References

Clarke, A. H. 1991. "Status Survey of Selected Land and Freshwater Gastropods in Utah." U. S. Fish and Wildlife Service, Denver, Colorado.

Pilsbry, H. A. 1948. Land Mollusca of North America. The Academy of Natural Science of Philadelphia Monographs, Philadelphia.

U. S. Fish and Wildlife Service. 1995. "Kanab Ambersnail (Oxyloma haydeni kanabensis ) Recovery Plan." U. S. Fish and Wildlife Service, Denver, Colorado.