Under pressure

Some of the earth’s oldest species are at risk

Chuckwallas like this one are among the reptile species facing an uncertain future due to habitat destruction and commercial collection.

Chuckwallas like this one are among the reptile species facing an uncertain future due to habitat destruction and commercial collection.

The Nevada Natural Heritage Program keeps a list of at-risk, rare, threatened, and endangered species, including amphibians and reptiles, at http://heritage.nv.gov/lists/track.pdf.

Amphibians and reptiles have been around since the dawn of the dinosaurs, and they’re some of the earth’s most interesting creatures. The Komodo Dragon, Gila monster, African bush viper, king cobra, and poison dart frog are all members. But these animals face widespread pressure from humans and nature alike.

According to AmphibiaWeb.com, nearly one-third of the world’s 6,300 amphibian species—frogs and toads, newts and salamanders—are threatened, and a global conservation effort is underway. In the Western United States, the main reasons are habitat loss due to water development, introduction of exotic species, pesticides and disease.

“The Western U.S. is one of the main hotspots for species extinction, population decline and reduced biodiversity,” says David Bradford, chair of the California-Nevada Amphibian Population Task Force. “We don’t have as many species as tropical regions, but the at-risk fraction is large.”

Amphibians require water to live, and Nevada is already the driest state in the nation. Add to that the diversion of water bodies for cities and agriculture, and the burden on indigenous species increases dramatically. Non-native species also pose a risk. Introduced trout, bullfrogs and crayfish compete for food with local amphibians, and bullfrogs prey on native species. Crayfish eat eggs and are able to go underground or over land when water dries up.

Widely used pesticides like Atrazine are deadly for amphibians, disrupting their endocrine systems. Chytridiomycosis is a disease caused by the pathogen Batrachochytrium dendrobatidi. “This disease is a puzzle to everybody,” says Bradford. “Some species get wiped out, and some manage to live with it.”

As for reptiles, Nevada is home to more than 50 native species of them, including snakes, lizards, geckos, iguanas, skinks and Gila monsters. Three big problems are lack of information, habitat destruction and commercial collection.

“The desert tortoise is well-studied, but we don’t have enough baseline information on other species to help monitor and maintain their populations,” says UNR biology graduate student Chris Gienger. “Their low densities and nocturnal movement make them tough to census.”

Gienger says problems are much worse in populated areas like Clark County than in the huge swaths of undeveloped land in central Nevada.

Like other rare and intriguing animals, exotic reptiles are frequently sought by collectors and would-be pet owners. Unfortunately, reptiles usually don’t make good pets. “Reptiles, like birds, have a wide range, specific diet and complex social structure in nature, and now they’re being kept in a cage or terrarium,” explains Dr. Mark Ditsworth at King’s Row Pet Hospital. “Their physical and mental health both suffer, and they tend to injure themselves out of deprivation and stress.” He adds that reptiles live a long time, and the initial novelty of owning such a pet usually wears off quickly.

The Nevada Department of Wildlife requires a permit for the commercial collection of unprotected reptiles and amphibians but sets no catch limit. Interestingly, state regulations compel all of these animals be shipped out of state. It’s illegal for stores in Nevada to carry native species, but it’s not illegal to capture or sell them. This policy promotes the loss of endemic species and biological resources in the state.