Listing actions

Endangered Species Bulletin, July-August, 2002

From December 2001 through January 2002, the Fish and Wildlife Service published the following proposed and final Endangered Species Act (ESA) rulemakings in the Federal Register.

Emergency Listing

Tumbling Creek Cavesnail (Antrobia culveri) On December 27, under the emergency provisions of the ESA, we gave immediate protection to the Tumbling Creek cavesnail, a unique aquatic snail found only in one cave stream in southwest Missouri. The Tumbling Creek cavesnail's population has declined significantly in recent years, and biologists believe that the species may face imminent extinction. Our action places the cavesnail on the endangered species list for 240 days. During this time, we will evaluate a proposed listing rule, which we also published on December 27; if approved, it would give the species long-term protection under the standard provisions of the ESA.

The Tumbling Creek cavesnail measures only about one-tenth of an inch (2.5 millimeters), is white, and is blind. Tumbling Creek Cave supports a high diversity of species. Several species of invertebrates, previously unknown, have been discovered there, and the cave also hosts colonies of gray bats (Myotis grisescens) and Indiana bats (Myotis sodalis), both of which are already listed as endangered. The cave itself is privately owned, while the land in the surrounding watershed is in both public and private ownership.

Biologists monitoring cavesnail populations in Tumbling Creek Cave over recent years have noted a sharp decline. The specific cause is unknown, but biologists believe that deteriorated water quality is a likely cause. Species such as the cavesnail that depend on underground water systems are highly vulnerable to changes in water quality and quantity. These underground systems are recharged by water filtering down from the surface, and land-use activities on the surface can affect water quality below. Water entering Tumbling Creek Cave from the land surface around the cave may contain silt or pollutants.

Proposed Listing Rules

Island Fox (Urocyon littoralis) Four rare subspecies of the tiny, docile island fox inhabiting four of the Channel Islands off of the southern California coast may receive ESA protection. On December 10, we proposed to list the Santa Cruz Island fox (U. l. santacruzae), Santa Rosa Island fox (U. l. santarosae), San Miguel Island fox (U. l. littoralis), and Santa Catalina Island fox (U. 1. catalinae) as endangered.

Fox populations on each of the islands, including the three within Channel Islands National Park, have dropped dramatically since 1995. On Santa Cruz Island, the population decreased from 1,300 to fewer than 100 animals. Island foxes on San Miguel and Santa Rosa islands no longer exist in the wild, and captive breeding programs are underway on both islands. Fewer than 200 foxes occur in the wild on Santa Catalina Island and the fox is being bred in captivity. Based on studies conducted as recently as 1999, the four subspecies of Channel Island foxes have a 50 percent chance of extinction over the next five to 10 years.

The primary causes of the decline of these island fox subspecies are predation by golden eagles (Aquila chrysaetos), the rapid spread of canine distemper through the Santa Catalina island subspecies, and habitat degradation caused by the introduction of sheep, goats, rabbits, deer, elk, cattle, pigs, and horses.

Biologists speculate that island foxes, which are smaller than house cats, may have gotten to the islands more than 18,000 years ago by floating on debris from the mainland during a storm, earthquake, or other natural event. At that time, when ocean levels were lower, the foxes inhabited one land mass called Santarosae that consisted of what later became San Miguel, Santa Rosa, and Santa Cruz islands. As sea levels rose and the northern Channel Islands separated, each fox population became genetically distinct. Foxes arrived between 2,200 to 3,800 years ago on the southern Channel Islands of Catalina, San Clemente, and San Nicolas, and were likely introduced by Native Americans, who may have kept them as pets.

Island foxes are inquisitive and generally show little fear of humans. They are grayish-white and black on the back and dull white on the underbelly. The base of the ears and sides of the neck and limbs are cinnamon-rust colored. As opportunistic foragers, island foxes--the largest native carnivore on the islands--will eat a wide variety of plants and small animals. They live in a wide variety of island habitats. When a female is ready to give birth in the spring, she will find a rock crevice or hollow stump and deliver from one to five pups, which are cared for by both the male and female for several months.

In October 2001, we awarded $504,000 in grants to the state of California to develop and put into effect a Candidate Conservation Agreement for the Santa Cruz Island fox. This grant will fund recovery actions for the fox that are identified in the state's draft recovery plan for the species. These actions include relocating golden eagles from Santa Cruz Island back to the mainland, undertaking captive breeding of the foxes, monitoring, and tracking causes of mortality. We also provided a $10,800 grant to fund the development and initial implementation of a Candidate Conservation Agreement for the Santa Catalina Island fox and the island loggerhead shrike.