Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bighorn sheep threatened by climate change, finds new study

12.02.2004


A study led by researchers at the University of California, Berkeley, has linked population declines of California’s desert bighorn sheep with the effects of climate change. What’s more, many of the state’s remaining bighorn populations could face extinction if certain global warming forecasts for the next 60 years come true.


A desert bighorn sheep in the Old Woman Mountains of the Mojave Desert. (Photos by Clinton W. Epps, UC Berkeley)



In the study, which is published in the current issue of Conservation Biology, the authors found that of the 80 groups of desert bighorn sheep known to have roamed California’s mountains over the past century, 30 are now extinct.

In their investigation of the population decline, the researchers evaluated impacts ranging from contact with domestic livestock, which can lead to the spread of disease and competition for food, to poaching, mining, human disturbance and other factors. They also analyzed climatic variables such as temperature and precipitation that affect the availability of vegetation and dependable sources of spring water for the sheep.


UC Berkeley researchers have linked the effects of climate change with population declines of sheep in California, like this bighorn in the Old Woman Mountains of the Mojave Desert.

"Climate was consistently correlated with extinction in a way the other factors weren’t," said Clinton W. Epps, a doctoral student in environmental science, policy and management at UC Berkeley’s College of Natural Resources and lead author of the paper. "The harsh environment inhabited by desert bighorn sheep already has them walking on a knife’s edge. It doesn’t take too much to push them off. The bottom line is that more than one-third of the populations that were once known are now gone," said Epps.

From 1901 to 1987, the mean annual temperature in the deserts of the southwestern United States increased by about 1.8 degrees Fahrenheit, which is considered significant by climatologists. In addition, annual precipitation dropped about 20 percent in southeastern California over the last century. According to the study, groups of bighorn sheep were more likely to be lost in lower elevation mountains where there were higher average temperatures and less precipitation.

The authors examined population data on the state’s desert bighorn sheep, or Ovis canadensis nelsoni, collected since 1940 by biologists and California Department of Fish and Game researchers. They also used historical records from local areas where the sheep were known to have lived, but had since disappeared.

Desert bighorn sheep primarily live in small, isolated groups throughout the mountain ranges of the Sonoran, Mojave and Great Basin deserts of the southwestern United States. In southwestern California, they are also found in the Transverse and Peninsular mountain ranges.

Bighorn has been a species of concern among conservationists since they were first protected by California legislation in 1873. Statewide, the population of desert bighorn is estimated at 3,500. Bighorn in the Peninsular and Sierra Nevada mountain ranges are listed as state and federal endangered species.

"When you start losing bighorn sheep from some mountain ranges, it affects the collective population," said Dale R. McCullough, professor of ecosystem sciences at UC Berkeley’s College of Natural Resources and co-author of the paper. "Any decline in vegetation makes it more difficult for sheep to move among the different habitat clusters, which have become fewer and more spread out. Where they used to be able to move more readily to other mountain ranges to help repopulate or recolonize a habitat area, they must now cross an intervening desert."

McCullough noted that effects on populations from global warming are easier to detect in bighorn sheep than species of other large mammals that are more uniformly distributed over the landscape. "Other large mammals may shift north more gradually as a result of global warming, but that trend is harder to detect in the short term," he said.

The authors also looked at predictions of how climate may change in the next 60 years. For scenarios that predict a minimum temperature increase of 1.3 degrees Fahrenheit, there is no significant increase in the average probability of extinction. However, in scenarios that predict a more serious temperature increase of 3.6 degrees Fahrenheit and a 12 percent decrease in precipitation, the probability of extinction increases significantly from a baseline of 20 percent to 30 percent in the next 60 years.

Epps points out that this increase is an average of the extinction probability calculated for each group remaining in southern California. The risks for some individual groups, particularly those that live at lower elevations, are significantly higher.

"Our study illustrates how sensitive certain populations can be to changes in climate, whether man-made or not," said Epps. "Cases like this give conservationists some ammunition when talking about the importance of controlling global warming."

Other co-authors of the study are John D. Wehausen of the White Mountain Research Station, Vernon C. Bleich of the California Department of Fish and Game, and Jennifer L. Rechel of the U.S. Forest Service.

Sarah Yang | UC Berkeley
Further information:
http://www.berkeley.edu/news/media/releases/2004/02/10_sheep.shtml

More articles from Ecology, The Environment and Conservation:

nachricht Treatment of saline wastewater during algae utilization
14.05.2019 | Jacobs University Bremen gGmbH

nachricht Plastic gets a do-over: Breakthrough discovery recycles plastic from the inside out
07.05.2019 | DOE/Lawrence Berkeley National Laboratory

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

Im Focus: A step towards probabilistic computing

Working group led by physicist Professor Ulrich Nowak at the University of Konstanz, in collaboration with a team of physicists from Johannes Gutenberg University Mainz, demonstrates how skyrmions can be used for the computer concepts of the future

When it comes to performing a calculation destined to arrive at an exact result, humans are hopelessly inferior to the computer. In other areas, humans are...

Im Focus: Recording embryonic development

Scientists develop a molecular recording tool that enables in vivo lineage tracing of embryonic cells

The beginning of new life starts with a fascinating process: A single cell gives rise to progenitor cells that eventually differentiate into the three germ...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Summit charts a course to uncover the origins of genetic diseases

22.05.2019 | Life Sciences

New study finds distinct microbes living next to corals

22.05.2019 | Life Sciences

Stellar waltz with dramatic ending

22.05.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>