Small animals at risk as Earth warms from climate change
Sat, 10/02/2010 - 05:24 | 
Earth Activist
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- Small mammals at greater risk from global warming than once thought, say U.S. biologists
- 12,000-year old fossils reveal some small species have never recovered their populations
- Many small mammal populations may already be at tipping point, researchers say
(CNN) -- The biodiversity of small mammals in North America may already be close to a "tipping point" causing impacts "up and down the food chain" according to a new study by U.S. scientists.
Examining fossils excavated from a cave in Northern California, biologists from Stanford University, California uncovered evidence that small mammal populations were severely depleted during the last episode of global warming around 12,000 years ago.
Many species, say researchers, have never recovered their populations leaving them vulnerable to future rises in temperature.
Deposits in Samwell Cave in the foothills of the southern Cascades mountain range revealed that populations of gophers and voles during the period (the end of the Pleistocene epoch) were on a par with those of deer mice.
But while the deer mice population thrived in the warming period and has become one of the most common small mammals in the U.S. today, gophers, voles and other small species' populations fell away permanently.
The decline in small mammal species during the period contributed to a 30 percent decline in biodiversity, according to the study.
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