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Scientist ponders disappearing species in 'Year of the Rabbit'

February 03, 2011

The Chinese New Year heralds the “Year of the Rabbit” on Thursday, Feb. 3; a year that holds particular significance for Arizona State University professor Andrew Smith. Smith is one of the world’s leading experts on pikas in China and the chair of the International Union for Conservation of Nature (IUCN) Species Survival Commission’s Lagomorph Specialist Group.

“As we enter this new cycle in the Chinese zodiac, nearly one in four rabbits, hares and pikas, from the taxonomic order known as lagomorphs or hare-shaped animals, are listed on IUCN”s Red List of Threatened Species™,” warns Smith.

Despite rabbits’ reputation as prolific breeders, Smith and other conservationists point to habitat loss, overhunting and disease as some of the major threats faced by lagomorphs. For example, while all domestic rabbits are descendants of the wild European rabbit, Oryctolagus cuniculus, this species has drastically declined in its native range on the Iberian Peninsula as a result of rabbit hemorrhagic fever and habitat loss. In Portugal, 30 percent of the species was lost in 10 years; and, elsewhere, deaths from the viral disease range from 40 to 100 percent. 

So what’s one less rabbit in the pot? Many lagomorphs are “keystone” species, which means that their impact on the environment is disproportionate relative to their numbers. They are a critical to the health of land they tunnel in, to the plants that grow, and up the food chain to the predators that feed on them, Smith says. “Lagomorphs include some of the most endangered species on the planet. Because of their ecological importance as prey, population declines of lagomorphs have led to catastrophic declines in predator species.”

Luis Ruedas, a member of the Lagomorph Specialist Group and professor at Portland State University, notes that “the reduction in rabbit numbers in the Iberian Peninsula led to a decline in the ‘Critically Endangered’ Iberian Lynx, Lynx pardina, as well as the ‘Vulnerable’ Spanish Imperial Eagle, Aquila adalberti.”

In addition, some lagomorphs are important game animals formerly occurring in areas that are economically depressed, says Smith. “All these factors mean that strong action is necessary to conserve this group of animals, key players in the world’s ecosystems.”

More than 15 lagomorphs have been Red-listed, including rabbits in South Africa, Sumatra, India, Nepal, Japan, and four species in Mexico. Even members of the pygmy rabbit, Brachylagus idahoensis, once thriving throughout the Great Basin in the United State,  are in decline, and have become extinct in Washington.

Smith’s favorite study animal, the plateau pika, Ochotona curzoniae, is also a keystone species. Pika burrows on the Tibetan Plateau provide habitats for other rare and geographically-restricted species. Hume’s ground pecker, Pseudopodoces humilis, and at least five species of snow finch depend on pika burrows, as do some species of lizard. Similarly, plateau pikas are an integral prey species for several species of weasel, fox, wolf, the ‘Near Threatened’ Pallas’s cat, Otocolobus manul, and the brown bear, Ursus arctos. More importantly, pika burrowing activities contribute to soil turnover and enrichment, which leads to increased plant species richness in areas they inhabit. This soil turnover also promotes nutrient cycling in the soil, and decreases the potential for erosion during heavy monsoons. In spite of the benefits to the environment, pikas have, like prairie dogs, been the target of extensive and long-lasting poisoning campaigns.

Leading the list of four endangered pikas is the Ili Pika, Ochotona iliensis. First described about 30 years ago, it lives in the remote Tian Shan mountains of northwest China. Recent censuses have shown that since its discovery it has disappeared from half of its previously known locations.

“Without changes in human activities, preservation of habitat and recognition of their importance and their plight, we might soon find bunnies joining the tiger on the road to extinction,” says Smith, who is a President’s Professor in the School of Life Sciences in ASU’s College of Liberal Arts and Sciences.