Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Bighorn sheep threatened by climate change, finds new study


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:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

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: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Inflammation Triggers Unsustainable Immune Response to Chronic Viral Infection

24.10.2016 | Health and Medicine

Microbe hunters discover long-sought-after iron-munching microbe

24.10.2016 | Life Sciences

Seeking balanced networks: how neurons adjust their proteins during homeostatic scaling.

24.10.2016 | Life Sciences

More VideoLinks >>>