Denver Zoo Announces AZA Accreditation

We’re thrilled to announce that Denver Zoo has achieved accreditation by the Association of Zoos & Aquariums (AZA). This prestigious accreditation reflects our unwavering commitment to animal care, wildlife conservation, education, science, and recreation. We’ve undergone an extensive and comprehensive evaluation of our operations and programs, resulting in a well-deserved five-year accreditation. This reaffirms our position as one of the top zoos in North America and a leader in animal care and conservation. Denver Zoo has maintained its status as an AZA-accredited facility since it was first accredited in 1976.

“AZA accreditation is the ultimate stamp of approval for our profession, and assures our guests and members that we’re providing the best possible care for our animals and creating a safe, enjoyable experience for our community. We’re beyond proud to be among the very few zoos and aquariums in the world that maintains such a high standard across our programs and operations.”  
Bert Vescolani, President & CEO of Denver Zoo.

It’s worth noting that fewer than 10 percent of the 2,800 wildlife exhibitors licensed by the United States Department of Agriculture (USDA) under the Animal Welfare Act meet the comprehensive standards of AZA accreditation. As an accredited organization, we’re subject to evaluation every five years by a team of expert inspectors who assess animal welfare, care, and management, including living environments, social groupings, health, and nutrition. They also evaluate all other aspects of our operations, from our involvement in wildlife conservation and research to our guest services, education programs, and finances.

We believe this accreditation process is of utmost importance. Every year, AZA sends over 200 accreditation inspectors worldwide to review applications, and we have nearly 40 facilities participating in our Pathway Toward Membership program, reflecting the growing significance of independent accreditation. AZA’s standards are continually updated to incorporate cutting-edge zoological practices based on the latest animal well-being science and research, attracting the best-of-the-best zoos and aquariums to be part of our association.

In addition to our AZA accreditation, Denver Zoo earned the American Humane Certified™ seal in 2020 for our exceptional treatment of the animals in our care. This achievement, similar to an AZA inspection, required us to pass rigorous, expert third-party audits. We join a distinguished group of leading zoological institutions that have received the American Humane Certified™ designation.

Eirina’s Baby Bliss

We’re beside ourselves with joy…our Sumatran orangutan sayang (baby) arrived on Sunday, August 27! You may be able to catch a glimpse of the adorable “redhead with bedhead” as she bonds with mom Eirina and endures the sweet (and persistent) curiosity of the rest of the family. 

Our animal care and health teams report that mom and baby—who is believed to be a female, and whose name is yet to be determined—are thriving in their Great Apes habitat in Primate Panorama. This is Eirina’s first baby after receiving a breeding recommendation as part of the Sumatran Orangutan Species Survival Plan and provides an invaluable boost to the Critically Endangered species. Our animal health team will be conducting a DNA test in the coming weeks to determine whether the baby’s father is 30-year-old Berani, or 15-year-old Jaya. 

Eirina joined us from Germany’s Dortmund Zoo in 2016, and has since enjoyed spending time with the Zoo’s other female orangutans—including Hesty (13) and Cerah (5). Shortly after we announced Erina’s pregnancy in April, the mom-to-be and her care team made national news when Animal Care Specialist Cindy Cossaboon was able to soothe the first-time mom’s morning sickness by making her the same tea she drank when pregnant with her own daughter. 

The birth of a healthy Sumatran orangutan baby marks a momentous occasion, both for Denver Zoo and the global conservation community. Sumatran orangutans are listed as Critically Endangered by the International Union for Conservation of Nature (IUCN) with a rapidly declining wild population due to habitat loss, illegal hunting and the black-market pet trade.  

At Denver Zoo, all babies are precious—but there’s even more cause for celebration when we get a win for a Critically Endangered species. As a non-profit conservation organization, we rely on YOU, our beloved community to support the essential work we do on campus, across Colorado and around the world. Please consider donating to our Orangutan Baby Registry and stay tuned for more updates! 

We hope you’ll swing by soon to see the new baby! Remember, your visit supports our wildlife conservation efforts in Colorado + worldwide. Be sure to follow us on FacebookInstagramTwitter and TikTok for updates on our 3,000 wonderful animals. 

Denver Zoo Debuts Boreal Toad Community Science Effort

By: Sam Hengge, Boreal Toad Project Assistant

How do modern zoos and aquariums meet the challenge of involving local communities in conservation efforts? One way Denver Zoo’s conservation team has sought to meet this challenge is through a brand-new community science program focused on Colorado’s endangered boreal toad (Anaxyrus boreas boreas). As a part of their participation with “Team Toad,” volunteers from throughout Colorado have been learning how to survey a variety of high-elevation wetlands in search of this rare amphibian. Within one summer of launching the program, community science efforts have already begun making an impact. 

Once widespread at elevations of 8,000-12,000ft in the southern Rocky Mountains, the boreal toad has largely disappeared from its historical range across the west. While boreal toad populations vary across surrounding states, in Colorado there are approximately 800 adult boreal toads remaining. Boreal toads are largely threatened by habitat loss and chytridiomycosis, a fungal pathogen leading to the decline of many amphibians worldwide. With over half of their breeding sites positive for chytrid, boreal toads have been largely susceptible to this disease. 

To help bring the boreal toad back from the brink of extinction in Colorado, Denver Zoo began assisting Colorado Parks and Wildlife in their conservation efforts by implementing a captive breeding program. Denver Zoo’s interest in boreal toads originally began in 2010 with a set of Utah boreal toads that were successfully bred and reintroduced in 2019. Following the success of these efforts, Denver Zoo shifted their focus towards Colorado boreal toads in 2022, leading to the successful breeding and reintroduction of their tadpoles/metamorphs back into the wild.  

To supplement captive breeding efforts, Denver Zoo also debuted a boreal toad community science project in the summer of 2022. After putting out the call for “Toad Trekkers,” Denver Zoo staff trained 76 interested community science volunteers from across the state to conduct amphibian surveys among target wetlands. Participants learned how to distinguish boreal toads from other amphibians and were taught how to swab specimens for chytrid. Additionally, volunteers conducted waterbody assessments for evaluating the quality of wetland habitats as potential reintroduction sites.  

In August 2022, a small group of Denver Zoo staff and volunteers found a boreal toad near Buena Vista, CO in a wetland where the species was believed to be absent after years without any sightings. As a result of this discovery, Colorado Parks and Wildlife altered how they were managing the wetland by halting a toad-stocking that had originally been planned in the area.  

This past summer, in addition to training a new round of “Toad Trekkers,” Denver Zoo surveyed a new set of wetlands with community science volunteers and made additional boreal toad discoveries. Following the success of the last two field seasons, Denver Zoo’s conservation team is hopeful that community science efforts will continue having a positive effect on boreal toad conservation in Colorado.  

 Remember, your visit supports our wildlife conservation efforts in Colorado + worldwide. Be sure to follow us on FacebookInstagramTwitter and TikTok for updates on our 3,000 wonderful animals. 

Rowdy Research

By Maura Davis, Curator of Large Mammals 

“Where are your females?” 

“Why don’t you have babies?” 

These are among the most common questions we get at Denver Zoo about our Asian elephant herd, and while our answer isn’t always what a guest is looking for (we don’t house females, so no babies here!), the way we take care of elephants in Toyota Elephant Passage is part of a larger goal to better understand male elephant socialization in the wild, and in human care.  

Toyota Elephant Passage opened at Denver Zoo in 2012 and was specifically designed to hold bulls.  In 2016, we started socializing male Asian elephants and our team of elephant care specialists  dedicated their time to learning as much about the integration process and consequences of those interactions as possible. Many zoological institutions that are housing male elephants often experience difficulties in socializing them as they get older due to numerous changes that occur as they mature, the most significant being their annual hormonal cycle called musth.   

The social structure of the herd in Denver was specifically designed to have a mature male (Groucho, age 53), who can teach and lead with patience and appropriate dominance, and a range of younger bulls who recently left their family groups to come and learn from Groucho’s teaching. As these younger males mature, they could be recommended to move elsewhere to a breeding institution to continue working with the Association of Zoos and Aquariums’ Species Survival Plans efforts to keep genetic diversity within the AZA’s Asian elephant population. As more male elephants are born, there will be a growing need for other institutions to house multiple male elephants, so learning best management practices and the importance of social hierarchy are important to set those other facilities up for success in the future.  

Denver Zoo has been working with researchers over the last several years to study multiple aspects of male management, and recently published a study titled “Age and Social History Impact Social Interaction Between Bull Asian Elephants at Denver Zoo.”  In this study, we found that behavior significantly changed when the mature male was present and that including at least one mature male in social groupings may reduce competition between adolescents. This has helped us understand how to best set up introductions of new elephants into our herd by starting with the the most mature male to help guide appropriate interactions when a new bull is establishing himself in the group. 

While this research helps us understand our own herd better, it will also be used worldwide to support the care of elephants in their native ranges, and in other accredited institutions. In India, the research is able to help guide governmental policy regarding the removal of adult males from groups of younger males in wild herds. Young males without the guidance of an adult bull show more tendencies to raid crops and cause damage in populated areas.  

We were able to see this research in practice with the arrival of our newest juvenile, Duncan. Duncan has only been at Denver Zoo for two weeks, but is already acclimating well with members of our herd, thanks to the work of our elephant care specialists. He spent his first day with Groucho to ensure Duncan had the mature male as support to help guide appropriate introductions to the younger elephants.  He has since met 14-year-old Chuck and 13-year-old Jake while under Groucho’s guidance. Our animal care specialists will continue to introduce him to other members of the group as he settles in.  

Research is a time-consuming process, but the insights gained, and the ability to share them with other organizations caring for Asian elephants, are invaluable. And thanks to our dedicated team, we now know more about male Asian elephant socialization than we ever have.  

Conservation Through a Different Lens

By Kristi Odom 

I will admit, I was skeptical about zoos. As a wildlife photographer and filmmaker, I spent countless hours observing animals in their natural habitat in some crazy-remote locations. My passion has grown quickly for the beauty of nature and so has my fight to try and use photography to protect it.  

Like many people in 2020, I found myself wanting a change, and I moved to Colorado It felt like a natural fit since I’m always looking for stories about people who fight to save wildlife, to celebrate those heroes and to help show the power people can make protecting our planet. I found a group of more than 400 volunteers that hike to high altitudes to count and monitor pikas. The first trip sparked my curiosity and excitement.  This small rabbit relative is a climate indicator, and with temperatures changing in the mountains, their livelihood is becoming more challenged. The Pika Project is run by a partnership with Rocky Mountain Wild and Denver Zoo. I was so inspired by the work, I ended up pitching and getting this story published online for National Geographic.It was an honor to tell a story about an experience I loved so much. The piece not only talked about climate change, but also the collaboration between individuals, organizations and biologists to protect a threatened species.  

This was my introduction to Denver Zoo. Not a visit to the 86-acre campus, but getting out in the field with their experts. Getting to know all the key players in conservation at the Zoo, my first thought was, “Wow, this is a passionate group.” I learned about the many projects they were involved in, from working on the human wildlife conflict on Mount Evans (soon to be Mount Blue Sky), to the fight to protect Colorado’s only alpine toad, the endangered boreal toad. Talking with the director of Colorado Field Conservation at Denver Zoo, Stefan Ekernas, I learned about how the Zoo spends more than $2 million a year on protecting wildlife and wild spaces. While I have worked with many organizations that have helped protect individual animals, this was a bigger scale–it is a group that helps protect species. From there, I started learning about the Association of Zoos and Aquariums., an organization dedicated to the conservation, education, science and recreation efforts of zoos. AZA accredited zoos and aquariums spend around $160 million on conservation annually and have funded more than 2,500 conservation projects in more than 100 countries. Denver Zoo is one of the 242 AZA-accredited organizations in North America, and has supported or directly participated in more than 600 conservation projects in 62 countries spanning six continents.  

I suspect many people are like me, and had no idea the dedication that the Zoo had for protection of wildlife and wild spaces. They have a large community science program in which they inspire locals to get involved and protect their local wildlife, which anyone can join. Denver Zoo also build relationships with state and federal run wildlife managements, other zoos, native American tribes and conservation organizations, creating a huge impact through collaboration.  

Last summer, I proudly took my stepson to Denver Zoo. He saw animals from all over the world, ones he might never get the experiences to see in the wild, and I saw the awe and wonderment in his eyes. I told him about how the Zoo is fighting to protect them, pikas, tadpoles, big horns and all. It was the first time I had been to a zoo since I can remember, and it was a beautiful experience celebrating wildlife and the heroes that fight to protect it. All it took was looking at the Zoo through a new lens. 

Kristi Odom is a member of the of the International League of Conservation Photographers and a Nikon Ambassador.  Her accolades include over 60 international photography awards including 2 Nature’s Best Photography awards, which exhibited her images at the Smithsonian Museum of Natural History.  Her work has appeared either online and/or in print for the following clients: National Geographic, Nikon, Forbes, Rollingstone, Microsoft and Outside Magazine. 

Be sure to follow Denver Zoo on FacebookTwitterInstagramLinkedIn and TikTok for more great stories about the Zoo’s animals and conservation programs! 

Gladys, to Meet You

Dr. Gladys Kalema-Zikusoka has spent most of her life saving Critically Endangered mountain gorillas in East Africa, first as a veterinarian, and now as CEO and Founder of Conservation Through Public Health (CTPH). Her work has been recognized around the world, most recently as a National Geographic Explorer and previously as winner of the Sierra Club’s 2018 EarthCare Award. She spoke with Denver Zoo about the connection between animal and human health, and the important role zoos can play in wildlife conservation.

Dr. Gladys: I decided at the age of 12 that I wanted to be a vet because I grew up with many pets at home. So, I decided I wanted to become a vet, but that wouldn’t happen until later. When I was in high school, the biology teacher wanted to revive the wildlife club, and I was very interested. When he came up to me and said he wanted to start a wildlife club I was so excited. I just jumped into it and started straight away.

Dr. Gladys: I worked in the Uganda Wildlife Authority for four and a half years, then did a combined, zoo medicine residency at North Carolina Zoo and North Carolina University. After that, we started Conservation Through Public Health. I became passionate about this idea of public health being critical to wildlife conservation after my first year with the Wildlife Authority. It was one of my first cases, nine months into the job. I got a call that the gorillas were losing hair and developing white scaly skin. We were able to save three of the adults, but not the baby, by treating them with ivermectin. We later learned that the condition was caused by the local communities’ unhealthy sanitary practices. I developed brochures and held workshops with over 1,000 people in villages where the gorillas would come. Education of the community by a team of four advocates led to the villagers coming up with ideas for mitigating the problems that needed solving.

I started my residency program thinking when I am finished there, I will go back and I’ll work for a non-profit organization to support the work. So, I spent time learning how to raise funding for all the various facets of the organization.

Dr. Gladys: One Health is a model that addresses the health of people and animals together because they’re all interconnected. Animals can make people sick, and people can make animals sick. You cannot address one without addressing the other. I think COVID-19 helped people to understand this better, that human health and animal health are truly inseparable. We saw COVID in humans, but also in gorillas, tigers, lions, and mink. You’ll always have zoonotic diseases jumping back and forth. One Health addresses things like family planning, nutrition, sustainable agriculture, and associated issues like degradation of the environment in foraging for usable resources.

Dr. Gladys: Zoos play a very important role in education. Most people will not see gorillas, tigers or lions in the wild for themselves, but they can learn so much about them by seeing them in zoos. Zoos and educational institutions can also be helpful with providing or soliciting funding. Zoos that carry products like Gorilla Conservation Coffee and other goods made by locals in other countries are also supporting those economies, helping them be less reliant on industries that are harmful to animals.

Dr. Gladys: The great thing is there isn’t just one way to help wildlife. No matter where you are in the world, or where you are in your life there’s something you can do to make a positive impact. Use social media to spread the word about important issues that need to be addressed. Buy Gorilla Conservation Coffee or other products made locally, send donations through zoos to support projects in the wilds. Even just being more conscious about your impact on wildlife can make a difference.

Denver Zoo, CPW Release Endangered Toads

Last November, Denver Zoo and Colorado Parks & Wildlife (CPW) launched a new initiative aimed at boosting the state’s population of boreal toads, a species listed as endangered in Colorado and New Mexico. Starting with 95 adult toads from CPW’s Native Aquatic Species Restoration Facility in Alamosa, experts from the Zoo spent more than six months preparing the toads for breeding, and nurturing their offspring leading up to their release into the wild. On Tuesday, June 28, teams from the Zoo and CPW trekked into a remote site in Gunnison National Forest to introduce 570 tadpoles into wetlands that officials hope could eventually host an established population of rare amphibians.   

“This was the result of a tremendous amount of hard work and planning by our partners at Colorado Parks & Wildlife, and members of our animal care and field conservation teams,” said Erica Elvove, Senior Vice President for Conservation Engagement and Impact at Denver Zoo. “Boreal toads face an extremely uncertain future in Colorado and have a good chance of going extinct without human intervention. We’re committed to continuing this effort with CPW for many years to come, and doing our part to make sure the species remains part of Colorado’s ecosystem for future generations.”  

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Once common in montane habitats between 7,000-12,000 feet in the Southern Rocky Mountains, the boreal toad has experienced dramatic population declines over the past two decades. The decline appears to be related to habitat loss and primarily infection by the chytrid fungus, which can infect the majority of the world’s 7,000 amphibian species, and is linked to major population declines and extinctions globally. Officials estimate there may be as few as 800 wild adult toads left in Colorado.   

“It was a very special day to join our partners from Denver Zoo to release boreal toad tadpoles that the Zoo produced at their facility,” said Daniel Cammack, Southwest Region Native Aquatic Species Biologist with CPW. “We’ve been stocking tadpoles at this site for about five years now, and we have high hopes that the tadpoles we introduced will contribute to a self-sustaining breeding population. It’s a pretty big win for boreal toad conservation.”  

We have been conserving endangered and critically endangered amphibian species for more than 15 years. In 2018, the Zoo became the first zoo in the Northern Hemisphere to successfully breed critically endangered Lake Titicaca frogs, and has since provided more than 250 healthy frogs to zoos and aquariums in the U.S. and Europe. In 2019, we used a hormone treatment to breed and produce more than 600 boreal toads, which were released in a remote area in southwestern Utah. And in 2021, we successfully bred critically endangered Panamanian golden frogs as part of the Association of Zoos and Aquarium’s Species Survival Plan.  

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CPW has devoted significant resources in the past 20 years toward researching the cause of boreal toad declines in the state and exploring ways to recover the species. Specifically, CPW researchers focus on developing methodologies for reintroducing toads in historically occupied habitats, detecting chytrid fungus in the wild, marking and identifying individual toads, and improving breeding success at the Native Aquatic Species Restoration Facility, which plays a critical role in the state’s efforts to restore populations of boreal toads.  

Our experts estimate that it will take many years to bring the species back to a level where it is secure in the Southern Rocky Mountains, and expect the collaboration to be a multi-year program. Additionally, as part of the wild release program, we launched a community science project where volunteers monitor the species’ high-country habitat to help officials understand the health of current wild populations and determine suitable locations for future reintroduction of toads bred at the Zoo. For more information, visit DenverZoo.org/Boreal-Toad-Conservation-Team.  

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A New Pair of Crocs

Tropical Discovery has two new crocodiles, but their presence here is for a limited time only. The critically-endangered, juvenile Orinoco crocodiles were two of many that hatched at Zoo Miami and Gladys Porter Zoo last year as part of a wild-release program. Orinoco crocodiles are native to the Orinoco River basin in Venezuela and parts of Colombia. They’re the most southerly species of crocodile, whose two biggest threats are habitat loss and being hunted for their meat. After hatching, the Species Survival Plan (SSP) managing Orinoco crocodiles reached out to other zoos to help raise the baby crocs, since raising that many crocodiles is a feat that requires more space and time than either zoo had. Enter Denver Zoo! 

Tropical Discovery is home to thousands of fish, reptiles, and even a handful of mammals, making it a perfect place for two young crocodiles. Not only do we have the space to house them, our Tropical Discovery keepers have the expertise to assist with raising these crocodiles until they’re ready for release. To ensure that all the crocodiles grow at the same pace and can be released around the same time, our team will follow a rearing protocol set up by the studbook keeper for the Orinoco crocodile SSP. Guests can come see the pair in the habitat between capybaras and piranhas, and watch them grow over the next 18-24 months. We’ll manage their care until they reach a meter in length, they’ll be large enough to be released into the Capanaparo River at the Santos Luzardo National Park in Venezuela. Once they’re at the release site, some of the crocodiles will be fitted with a satellite tracking device for constant monitoring of their movements and habitat utilization. Being able to track their movements will give us a better idea of how to preserve and care for the species for years to come. 

As a conservation organization, we’re proud to lend our expertise and facility to this important effort. Whether we’re out in the field rehabilitating species, or providing a short-term pit stop for a wild-release program, we’re focused on our mission to inspire communities to save wildlife for future generations. We hope you’ll join us! 

Follow along on our  Facebook, Instagram, TikTok and Twitter for more conservation stories! 

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Behind the Boreal Toad Project

Native Aquatic Species Coordinator Harry Crockett with Colorado Parks and Wildlife (CPW) answers some of our questions about how Denver Zoo got involved with boreal toads in Colorado, and how YOU can help save wildlife in our state. 

Denver Zoo: What inspired you to work for CPW? 

Harry Crockett: I always wanted to be a wildlife biologist, and always leaned toward things that live in the water, owing to a lifetime of fishing, working a number of seasons as a river trip guide, and other water-oriented passions. When I got my Masters at Colorado State University, my thesis project was in cooperation with Colorado Parks and Wildlife, so I got familiar enough with the agency to know I wanted to be part of it. I was lucky enough to get hired by CPW as a seasonal technician which made me even more sure of my career path. Working with the boreal toads has become one of the most compelling parts of my job.  

DZ: Why are boreal toads an important species to work on restoring in Colorado? 

HC: Aldo Leopold’s famous ecological insight that the first rule of intelligent tinkering is to keep all the parts, certainly applies to these toads–we don’t fully know the role they play in the montane environment but we know they have a role and it’s important. For those who need a more human-utilitarian reason to care about boreal toads, all amphibians are important indicators of aquatic and riparian system health because they are so much a part of both the aquatic and terrestrial worlds. They’re an early warning system about water quality and overall environmental health. Toads used to be very common throughout the Southern Rockies–there are many anecdotes from the 1960s and earlier of them being so abundant around montane wetlands at certain times of the year that one had to work to avoid stepping on them. And the fact that they have declined so greatly shows that something is badly amiss–an invasive disease in this case.  

On a basic level of connecting with another species, you don’t maybe think of toads as charismatic but boreal toads have a ton of personality. Interacting with them will definitely deepen your appreciation that even humble species are inherently important. I want my grandkids and all future generations to be able to go up in the mountains and encounter toads in their natural habitat, it’s part of the full experience of the greatness that is the Southern Rocky Mountains. 

DZ: How did Denver Zoo come to work with CPW on the boreal toad project? 

HC: The interest really started on the Denver Zoo side, going back more than 10 years, before I was even involved. Zoo staff would attend the Boreal Toad Conservation Team meetings every year, and we just kept up discussions about how we could increase our collaboration. For the past few years, the Zoo has housed and bred boreal toads for release in Utah, so we were very intrigued with that possibility for our toads from the Southern Rocky Mountain populations. When the greater space resources became available, CPW and the Zoo both jumped at the opportunity.    

DZ: What makes Denver Zoo uniquely qualified to be a partner in this project? 

The specific success at breeding boreal toads in captivity, that I mentioned above, was very compelling because that’s proven to be really hard to do. We had a lot of luck earlier on at the Mumma Native Aquatic Species Restoration Facility (CPW’s native species hatchery, producing 12 species of at-risk fish plus the boreal toad), but it’s been much more hit-and-miss for going on ten years now. The fact the Zoo was producing the same animal for Utah definitely caught our eye. But beyond that, we know the Zoo is a national leader in breeding and assisting in other ways with conservation of imperiled amphibians from around the world. To have such a great resource right here in our own backyard is certainly a unique opportunity.  

DZ: How can people do their part to preserve and protect Colorado’s natural species and spaces? 

HC: For the toads specifically, there are some very practical things you can do to help, and one of the biggest is to avoid behavior that might spread the chytrid fungus to new areas. Staying on trails is great; especially avoiding going from one wet area to another without changing/ drying / disinfection footgear in between. The same precautions will keep you from accidentally stepping on a toad or degrading sensitive wetland habitat. If you’re fishing, disinfect your waders when going from one body of water to another (you should be doing this anyway to avoid spreading whirling disease and other organisms that can imperil sport fisheries).  

More generally, support conservation in whatever way works for you. The Zoo has terrific volunteer and community science programs, and so does CPW.   Getting involved in a way that gets you interacting with a part of nature that you really care about is so much more personally rewarding than just writing a check, although donating money is also important if you can afford it.       

For more information about our boreal toad project click here and follow us on Facebook, Instagram, TikTok and Twitter for updates! 

Keeping Wildlife Wild on Mount Evans

By: Julie Krajewski, Colorado Conservation Specialist 

High on Mount Evans, visitors can enjoy views of mountain peaks, alpine lakes and glacier valleys, as well as the chance to see iconic Colorado wildlife, such as Rocky Mountain bighorn sheep, mountain goats, pika, and yellow-bellied marmots. The Summit Lake area is a National Natural Landmark and home to rare plants only found at Summit Lake and in the Arctic circle. With the highest paved road in North America providing the opportunity to drive to 14,130 feet, the Mount Evans Recreation Area attracts 200,000 visitors each year.  

While it is unusual to see mountain goats and bighorn sheep in areas with high human activity, on Mount Evans, the sheep and goats often congregate around parking lots and roads. This close proximity to humans can pose serious risks for both tourists and wildlife. Sheep and goats are susceptible to many hazards when near humans, including increased stress, behavioral changes, disease risk, and exposure to human food as well as human and pet waste. Bighorn sheep and mountain goats may act aggressively towards humans if they feel threatened. Both sexes of sheep and goats have prominent horns and are capable of inflicting serious injuries. In 2010, a hiker was killed by a mountain goat in Olympic National Park. 

In 2020, Denver Zoo began to study and address human-wildlife conflict on this iconic fourteener. While the Mount Evans Scenic Byway is typically open during the summer months, it was closed due to COVID during the 2020 season creating an experiment for how the presence/absence of huge crowds of visitors impacts wildlife behavior. With support from a National Geographic grant, DZ scientists used remote cameras to document how wildlife used the landscape while the road was closed.  

This work continued during the summer of 2021, when the road reopened to visitors. Last summer, Denver Zoo’s Field Conservation team began investigating how to discourage wildlife from congregating in high-human use areas. Bighorn sheep and mountain goats seek out sources of salt and other minerals in their environment. In addition to naturally occurring mineral licks, sheep and goats are drawn to human-created sources of minerals. Some examples of these mineral sources are salt on vehicles and roads, and minerals in human urine found at restrooms and other places humans and their pets urinate. We took soil samples at different locations across Mount Evans to look for signs of higher salt content or other pollution. Also in 2021, Denver Zoo scientists experimented with the use of mountain lion urine as a deterrent to discourage bighorn sheep and mountain goats from coming into the parking lot at Summit Lake. With signs of a predator in the area, goats and sheep may be less likely to enter the parking lot and to congregate around human-created mineral sources.  

Aside from interactions with humans, there are other potential dangers to unusually large congregations of bighorn sheep and mountain goats. A higher density of animals in a small area can lead to increased competition for resources and increased aggression within the herds. Larger groups also create the potential for increased disease transmission. The primary threat to bighorn sheep populations today is pneumonia, caused by the bacterium Mycoplasma ovipneumoniae. This bacterium was introduced from domestic sheep herds to wild sheep and goats. While mountain goats typically don’t become ill from Mycoplasma, they can be carriers of the disease and can spread it to bighorn, which are very susceptible and face high mortality rates when infected (70-90%). Large congregations of sheep and goats can create super-spreader events that put entire herds at risk. 

Denver Zoo’s work on Mount Evans continues in 2022 as we collaborate with Denver Mountain Parks, US Forest Service, and Colorado Parks and Wildlife to make Mount Evans a safer place for both visitors and wildlife. Some ways that you can help keep wildlife safe and healthy are to only observe wildlife from a safe distance, back away if bighorn sheep or mountain goats approach you, utilize available restrooms, and practice Leave No Trace principles (pack out what you carry in). And never feed wildlife. Keep an eye out for Denver Zoo staff if you’re on the mountain this summer — we’d love to answer any questions you may have about how to share the land with wildlife! 

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