A study by College of Forestry researchers found that cougars in Zion National Park—like wolves in Yellowstone National Park—profoundly impact other aspects of the ecosystem:
Ripple, W.J. and Beschta, R.L. (2006). Linking a cougar decline, trophic cascade, and catastrophic regime shift in Zion National Park. Biological Conservation 133:397-408.

Cougar Predation

Other Scientific Articles

Ripple, W.J., and Beschta, R.L. 2008. Trophic cascades involving cougar, mule deer, and black oaks in Yosemite National Park. Biological Conservation 141(5): 1249-1256.

News Articles

• Monitoring cougar in Yosemite Valley Difficult. San Mateo County Times June 22, 2008.
• Lack of predators harms wild lands. San Mateo County Times June 21, 2008.
• Cougar decline resuls in critical changes to Yosemite ecosystem Land Letter - E&E Publishing Service May 8, 2008.
• Yosemite: Protected but Not Preserved. Science Magazine May 2, 2008.
• How humans, vanishing cougars changed Yosemite. San Francisco Chronicle May 2, 2008.
• It All Falls Down: A plummeting cougar population alters the ecosystem at Zion National Park. Smithsonian Magazine/Smithsonian.com December, 2006.
• Cougar Predation Key To Ecosystem Health. ScienceDaily.com / University of Toronto October 25, 2006.