Bison, Bighorn Sheep,  
Boreal Toad + Beyond


Be a part of the difference we’re making in Colorado and around the world—support Denver Zoo Field Conservation programs!

As a global conservation organization with more than 25 years of fieldwork under our belts, Denver Zoo has a proven history of protecting wildlife and wild places around the world. We're lucky to live in a state blessed with ecological diversity, but even some of Colorado's iconic species are vulnerable to increasing threats.

So, here on our home turf, we work alongside a committed cadre of partners—including individuals, communities, industries and universities, non-profit organizations, agencies and more—to protect the species and ecosystems that define our Rockies and Plains. Here’s an overview of Denver Zoo's field conservation work from prairie to peak.


Protecting Iconic Species +
Habitats of the American West

Breeding a Brighter  
Future for Bison

By 1908, Denver Zoo’s 18 American bison were all that remained in Colorado. In our first official field conservation effort, the Zoo partnered with Yellowstone National Park officials and others to help propagate the endangered species. In 1914, the growing conservation herd was restored to Genesee Park and placed under the care of Denver Mountain Parks. Denver Zoo continues to work with DMP on bison conservation, prairie restoration and cultural reconciliation—and since 2021, we have worked with the City of Denver to Donate 47 bison to Native American communities as a form of reparations.

Safe Passage for  
Colorado’s Wildlife

Every year, 4,000 wildlife-vehicle collisions occur in Colorado, with tragic consequences. In 2018, Denver Zoo co-founded Summit County Safe Passages: a working partnership between state and federal agencies, non-profit organizations, the outdoor industry and mountain communities to help mitigate this critical issue with innovative wildlife crossing structures. Hundreds of species, including Rocky Mountain icons such as elk, the vulnerable black bear and the threatened Canada lynx are expected to use the structures to move safely within their extensive range.

Helping Endangered  
Toads Bounce Back

One of the species most severely affected by the deadly chytrid fungus is Colorado’s locally endangered boreal toad. In 2019, Denver Zoo became the first zoo to successfully breed this mountain-loving amphibian, ultimately releasing 682 tadpoles into the wild in Utah. In collaboration with Colorado Parks and Wildlife, we have now expanded our efforts to Colorado. In 2022, we released over 500 Zoo-born tadpoles into the Gunnison National Forest and launched a new community science project to monitor historic toad habitat across Colorado.

Balancing Recreation +  
Conservation at Mt. Evans

Mount Evans, the highest paved road in North America, receives more than 200,000 visitors per year. Visitors bring salt, which attracts bighorn sheep and mountain goats into parking lots and trailheads—creating human-wildlife conflict. Denver Zoo, with support from National Geographic, is stepping in to help resolve this conflict. We are taking soil cores to identify salt sources, engaging visitors to stop wildlife-feeding and other destructive behavior and deterring mountain goats and bighorn sheep by spreading mountain lion urine in parking lots.

The Little Lagomorph  
with a Huge Impact 

The Colorado Pika Project leverages the skills and passion of more than 500 community science volunteers to collect detailed data on the climate-sensitive American pika. As an indicator species, these diminutive rabbit relatives help us understand the effect of climate change. The Colorado Pika Project is a partnership between Denver Zoo and Rocky Mountain National Park, in collaboration with the White River National Forest, Rocky Mountain National Park, Colorado Parks & Wildlife, the University of Colorado Boulder and Colorado Mesa University.

Epidemic Intervention  
for Bighorn Sheep

For centuries, wild bighorn lived in harmony with the Diné (Navajo) people and their domestic sheep. Yet by the 1990s, the Navajo Nation bighorn population had plummeted to mere dozens—and today local herds are in the grip of a deadly pneumonia epidemic. Denver Zoo, in collaboration with the Navajo Nation Department of Fish and Wildlife, Colorado State University, Wildlife Conservation Society, is identifying high-contact areas and working with Diné herders to develop indigenous solutions for preventing disease spillover from domestic sheep into their wild cousins.


impact at
any altitude

As with all Denver Zoo Field Conservation programs, our Rockies / Plains efforts target long-term projects where need is high and investments are low—including near-endangered or locally endangered species, tribal conservation and inter-agency landscapes that can be difficult to navigate. 

And our work is having a measurable impact. To date, Denver Zoo's Field Conservation programs have made reparative donations of 47 American bison to Native American communities; leveraged the skills and passion of over 500 community scientists via the Colorado Pika Project; tested 90 bighorn sheep for the deadly pneumonia virus, bred and released 1,252 boreal toadlets in Utah and Colorado; and spread many gallons of mountain lion urine to discourage human-wildlife contact at Mount Evans/Blue Sky.


Denver Zoo is grateful for the network of partner and funding organizations working to affect meaningful change, including the following federal, state and local agencies:

Denver Mountain Parks
Colorado Parks and Wildlife
US Forest Service
National Parks Service
Continental Divide Research Learning Center
US Geological Survey
US Fish and Wildlife Service
Colorado Department of Transportation
Navajo Nation Department of Fish and Wildlife

We are also grateful for our partnerships with the following non-profits and universities:

Rocky Mountain Wild
Friends of the Dillon Ranger District
Wildlife Conservation Society
Walking Mountains Science Center
Independence Pass Foundation
Wilderness Workshop
University of Colorado Boulder
Colorado State University
Colorado Mesa University
Metro State University of Denver
Regis University