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Death Valley
Photographer's Guide


 
 
Critters in the News
         
Extinction Biology - that's how at least one herpetologist describes his field of study. With a third of the world's 5,743 amphibian species described as "threatened" by the Global Amphibian Assessment in 2004, and another 168 already gone, that phrase seems disturbingly accurate. And it's not just amphibians; reptiles are also in decline throughout the world and here in the United States. Global warming, habitat destruction, a fungal epidemic, and above all politics are having a combined effect that will lead to the extinction of hundreds of species in this century.

More than just one-day news stories, these are ongoing issues that provide textbook examples of how environmental policies and decisions affect our daily lives - and the lives of the millions of plants and animals with whom we share the Earth.
Mountain yellow-legged frog, Rana muscosaMountain yellow-legged frog California red-legged frog, Rana aurora draytoniiCalifornia red-legged frog
Yosemite toad, Bufo canorusYosemite toad San Francisco garter snake, Thamnophis sirtalis tetrataeniaSan Francisco garter snake
Bullfrog, Rana catesbeianaBullfrog Mojave desert sidewinder, Crotalus cerastes cerastesRattlesnakes
African clawed frog, Silurana spAfrican clawed frog Sceloporus occidentalis with tickLizards and Lyme disease
Once common in the high meadows of the Sierra Nevada, the mountain yellow-legged frog is sliding rapidly toward extinction. After disappearing from as much as 90% of its former range in recent years - due to habitat destruction, pesticides, and predation by non-native trout introduced for sport fishing - the remaining populations are dying off, the victim of a fungal epidemic exacerbated by global warming.
Mountain yellow-legged frog, Rana muscosa

California red-legged frog, Rana aurora draytonii
For the first time since 1969, a population of California red-legged frogs - the subject of Mark Twain's The Celebrated Jumping Frog of Calaveras County - has been observed living in Calaveras County itself. But that seems to be the only good news for Rana aurora draytonii. California’s most famous amphibian has been the subject of lawsuits and controversies over housing construction, habitat protection, and golf course management - and even led to a million-dollar fine for one real estate developer.
Another once-common high Sierra amphibian, the Yosemite toad is disappearing so quickly - and government agencies are moving so slowly - that many biologists fear Bufo canorus will be extinct before it's ever listed as an endangered species. Most of the Yosemite toad's habitat is within protected wilderness areas and national parks, but that's not enough to save it from "pesticide drift" from Central Valley farms, global warming, and water pollution.
Yosemite toad, Bufo canorus

San Francisco garter snake, Thamnophis sirtalis tetrataenia
The beautiful San Francisco garter snake, officially listed as an Endangered Species, has the misfortune of living in one of the most densely-populated areas of the country. Now extinct within San Francisco, it survives in a few scattered populations south of the city, and has been the subject of court orders involving construction at San Francisco International Airport and other sites on the S.F. peninsula.
Rattlesnakes are always controversial, especially as more and more formerly wild land is developed for suburban housing. What evolved as an efficient method for killing prey is now considered an unacceptable danger to residents and their pets; but in any conflict between rattlesnakes and people, it's invariably the snakes who lose.
Mojave desert sidewinder, Crotalus cerastes cerastes
         

Bullfrog, Rana catesbeiana
Bullfrogs are native to the eastern United States, but were introduced in the West by entrepreneurs to supply restaurants with frog's legs. It was an experiment that succeeded beyond anyone's expectations, with disastrous results for some native amphibian populations. A voracious predator, Rana catesbeiana will eat anything smaller than itself - and it's the biggest frog in the pond.
The chytrid fungus that's wiping out frog populations around the world is believed to have originated in Africa, and apparently began spreading in the 1940s and 50s when millions of African clawed frogs were exported around the world for use in pregnancy tests. Unfortunately, some of the frogs escaped and populations are now established in many countries, including the United States.
African clawed frog, Xenopus laevis

Western fence lizard, Sceloporus occidentalis, with tick
Can lizards prevent Lyme disease? Researchers at the University of California at Berkeley think so. They've found that the blood of Western fence lizards contains a substance that kills the Lyme disease bacterium, Borrelia burgdorferi, when a lizard is bitten by a tick carrying the disease. This may explain the relatively low incidence of Lyme disease in California despite its abundant tick population.
         
         
 
         
         



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Dan Suzio Photography
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