Denver Zoo

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Denver Zoo
Entrance pavilion
Date opened 1896
Location Denver, Colorado, United States
Coordinates 39°45′N 104°57′W / 39.750°N 104.950°W / 39.750; -104.950Coordinates: 39°45′N 104°57′W / 39.750°N 104.950°W / 39.750; -104.950
Land area 80 acres (32 ha)[1]
Number of animals 4,125 (2013)[2]
Number of species 613 (2013)[2]
Annual visitors 1.6 million (2001–2010 average)[3]
Memberships AZA,[4] WAZA[5]
Major exhibits Predator Ridge, North Shores, Tropical Discovery, Toyota Elephant Passage, Primate Panorama, Bear Mountain

The Denver Zoo is an 80-acre (32 ha) facility located in City Park of Denver, Colorado, United States. Founded in 1896, it is owned by the City and County of Denver and funded in part by the Scientific and Cultural Facilities District (SCFD). It was the most popular paid attraction in the Denver metropolitan area in 2005.[6]

The Denver Zoo was started with the donation of an orphaned American black bear. With the construction of Bear Mountain, it became the first zoo in the United States to use naturalistic zoo enclosures rather than cages with bars.[7] It expanded on this concept with Primate Panorama, featuring huge mesh tents and open areas for apes and monkeys, and with Predator Ridge, which has three separate areas through which animals are rotated so that their overlapping scents provide environmental enrichment. Toyota Elephant Passage, which opened on June 1, 2012, is divided into five areas for rotating the various species.

The Denver Zoo is accredited by the (American) Association of Zoos and Aquariums (AZA) and is also a member of the World Association of Zoos and Aquariums (WAZA). In 2009, the zoo achieved ISO 14001 certification. The Denver Zoo was named the "Greenest Zoo in the Country" at WREF 2012.


Early years[edit]

The Denver Zoo was founded in 1896 when an orphaned American black bear cub named Billy Bryan – short for William Jennings Bryan after the contemporary American politician – was given to Thomas S. McMurry (mayor of Denver from 1895–1899) as a gift. McMurry gave the hard-to-manage cub to the keeper of City Park, Alexander J. Graham, who started the zoo with this animal. Other animals at the young zoo included native waterfowl at Duck Lake, native prairie dogs, antelope which roamed the park, and a flock of Chinese pheasants, which later populated the eastern plains of the state.[7][8]

In 1905, a population of red squirrels was added to the zoo's collection; this population grew rapidly and decimated the bird population at Duck Lake. A plan to shoot the squirrels was scrapped when citizens protested. Instead, as many squirrels as could be caught were sent to the Denver Mountain Parks.[8]

The south tip of Bear Mountain was originally intended for monkeys but now houses coati.

Mid-20th century[edit]

The zoo was a motley menagerie until 1906, when Mayor Robert W. Speer declared that the zoo's "[p]rison bars can be done away with" in favor of "concrete rocks, waterfalls, trees, etc." Speer hired the city's landscape architect, Saco R. DeBoer, to draw up the plans for his renovation and appointed Victor H. Borcherdt as zoo director.[8]

Memorial marker to Velox

Borcherdt designed the Bear Mountain exhibit, which opened in 1918. This structure is 43 ft (13 m) tall and 185 ft (56 m) long, and cost $50,000 to build. It was built of dyed and textured concrete forms cast from Dinosaur Mountain just outside of Morrison, Colorado. Hidden moats replaced cage bars, and native plants and an artificial stream enhanced the natural look. The two main exhibits originally housed polar bears and grizzly bears. The south tip of the exhibit was designed to resemble Mesa Verde National Park. Originally it housed monkeys, but due to escape problems sea lions were housed there instead.[8][9] Between 1941 and 1961 it housed a female polar bear named Velox,[10] who became the mascot of the 31st U.S. Infantry Regiment in 1952.[11] Velox died at the zoo in 1961 and a memorial stone for her is displayed at the zoo.[12][13] Bear Mountain established Denver as one of the foremost among American zoos, and the Saint Louis Zoo hired Borcherdt after seeing the exhibit.[8]

Although other zoos in the region made extensive use of New Deal funds to upgrade their facilities, only one notable addition was made to the Denver Zoo between 1918 and 1950. Monkey Island was built in 1937 using funds from the Works Progress Administration. Mayor Benjamin F. Stapleton funded the zoo very little, and it was in poorly maintained condition when Mayor Quigg Newton was elected in 1947. Newton hired DeBoer, the architect involved with the zoo's design forty years before, to plan a rebirth. Starting with the 1950 overhaul of Monkey Island, the zoo has steadily added to and improved its exhibits.

The Denver Zoological Foundation was created in 1950, the same year that the zoo acquired its first elephant, Cookie.[14] A Children's zoo was opened in 1951 (since replaced by Primate Panorama). A perimeter fence was built in 1957, defining the zoo as a separate area but still within City Park. Automobile traffic in the zoo was finally eliminated completely in 1959.[15] Pachyderm Habitat was opened the same year, and Cookie was joined by a second elephant, Candy.[16]

The zoo opened the Feline House in 1964, a Giraffe House in 1966, and an Animal Hospital in 1969. Bird World was opened in 1975, followed by the Mountain Sheep Habitat in 1979, Northern Shores for polar bears, otters, and pinnipeds in 1987, and Wolf Pack Woods in 1988.[8]

The Marine Mammal Protection Act of 1972 made it impossible to keep the polar bears and sea lions in the Bear Mountain enclosure. This and its deteriorating condition lead to a $250,000 renovation of the exhibit starting in 1987. The exhibit reopened in 1989 with grizzly bears and Himalayan bears occupying the northern two exhibits and coatis in the southern tip.[9]


In 1993, the zoo opened the $11.5 million Tropical Discovery exhibit.[8] Designed by the Denver architectural firm Anderson Mason Dale, this indoor tropical garden topped by glass pyramids is the aquarium and herpetarium of the Denver Zoo, and its opening doubled both the number of species and the number of animals at the zoo. Along with the animals, 90% of which had never been on display at the zoo, there are over 250 species of plants represented in the exhibit.[17]

On November 6, 1994, twin polar bear cubs Klondike and Snow were born to a first-time mother named Ulu, who rejected the cubs. They were successfully raised by zoo staff and became a popular attraction. The bears were transferred to SeaWorld Orlando.[18] In 2012 Snow was transferred from Sea World in Orlando, Florida to the Reid Park Zoo in Tucson, Arizona, where she died unexpectedly on September 2, 2012.[19] Klondike died at SeaWorld Orlando on September 13, 2013.[20] Their story is commemorated at the Denver Zoo by a bronze sculpture located across from the main polar bear viewing area.[21]

On February 24, 2007, a jaguar mauled zookeeper Ashlee Pfaff inside the animal's enclosure. The jaguar was shot and killed by the zoo's emergency response team while rescuing Pfaff, who later died of her injuries at a local hospital. This event occurred despite zoo policy prohibiting direct contact between keepers and big cats.[22] An investigation by the zoo concluded the attack was the result of human error by Pfaff.[23]

In 2009, the Denver Zoo was the first zoo in the United States to achieve ISO 14001 certification. City park rebuilt its greenhouses in 2009, and as part of this project was able to provide the zoo with its own dedicated greenhouse.[3]

In 2010, the zoo, in cooperation with the City and County of Denver, drained Duck lake in order to remove sediment buildup and improve its water quality. Duck Lake is part of the 330-acre (130 ha) City Park but not part of the zoo, but it is a major nesting ground for black-crowned night herons and snowy egrets in the state. The nature walk along the lake shore was upgraded as part of the Asian Tropics project.[24]

In 2012, the zoo opened the $50 million Toyota Elephant Passage. The exhibit was originally announced in 2006 as Asian Tropics,[25] and bids for a general contractor were sent out in June 2009.[26] The exhibit was constructed by the Kiewit Building Group and groundbreaking was on December 2, 2009.[27] It was opened to the general public on June 1, 2012.[28]

Map of Denver Zoo


The Denver Zoo houses species from all over the world, including hoofed mammals, carnivorous mammals, primates, pachyderms, birds, reptiles, and fish. The zoo's animal collection contains 4,125 specimens representing 613 unique species.[2] The zoo is laid out in a large loop, with exhibits both inside and outside the loop. Current exhibits include the following:[29][30]

Bear Mountain[edit]

This historic exhibit, originally opened in 1918, is one of the first natural-style zoo exhibits in North America, and the first to use simulated concrete rocks. It underwent a $250,000 restoration between 1987 and 1989, and is now home to grizzly bears, Asiatic black bears, and coati.

Primate Panorama has plenty of room for its orangutans


Primate Panorama spreads over 7 acres (2.8 ha) and primarily houses apes and other larger primates. Tree-dwelling apes and monkeys live in open-air wire mesh tents that soar four stories high and cover more than an acre of ground. Inside these tents, the primates such as colobus monkeys and red-capped mangabeys can play and climb on twisting vines. Western lowland gorillas roam freely, climbing ropes and taking afternoon hammock naps in one of the largest gorilla habitats in the world. Orangutans have their own outdoor habitat where they can climb trees and swing in hammocks.

Jewels of the Emerald Forest pavilion features a meandering trail through diorama replicas showing four primate environments: Malagasy, South American forest floor and forest canopy, and primates of the night. Animals housed here include the aye-aye, titi and golden lion tamarin. Connecting to the building is an island exhibit that rotates several different lemur species.

The nearby Shamba offers a view of a Central West African village and is home to red river hogs.

Monkey Island was built in 1937 with funds from the Works Progress Administration. It was rehabilitated in 1950. During the warmer months, it is inhabited by hooded capuchin monkeys. It is surrounded by a moat that also houses some aquatic birds, including American white pelicans, in the summer. The moat is drained in the winter and the monkeys are housed in Monkey House.

Monkey house, facing Monkey Island, was the original primate exhibit in the zoo and currently still houses several species of monkeys, including those that are released on Monkey Island in the summer, as well as spider monkeys and gray langurs.

Predator Ridge is designed to represent the African savanna


Predator Ridge is a large exhibit representing the African savanna. It has the ability to rotate different African predators (Transvaal lions, spotted hyenas, and African wild dogs), whose overlapping scents provide environmental enrichment for the animals.

Feline House was created in 1964 and comprises two buildings with three large outdoor exhibits and 6 smaller outdoor exhibits connected to the indoor rooms. Cats can retreat inside in inclement weather but be outside part of the time as well. The larger outdoor exhibits are currently inhabited by striped hyenas, maned wolves, and Siberian tigers. Other species on exhibit here include snow leopards (with three cubs born in 2008), dwarf mongoose, Amur leopards, servals, northern tree shrews, and fossa.

Cheetahs have their own large enclosure across from Pachyderm Habitat.

Pachyderm Habitat[edit]

Currently home to black rhinos and hippos. The elephants and Malayan tapirs were moved to the Toyota Elephant Passage prior to its opening in June 2012. As of summer 2015, the pachyderm habitat is also home to a special area for children where they can learn how to be a zookeeper or meet small animals from the education collection. Two llamas came to the zoo for the new area.

Hoofed mammals[edit]

Hoofed mammals are generally housed in the center of the zoo. Hoofed mammals at the Denver zoo (counter-clockwise from the entrance) include Grevy's zebras, reticulated giraffes, Bactrian and dromedary camels, okapi, many species of antelope including bongo and gerenuk, and Cape buffalo.

Giraffe House was created in 1966 and, along with the outdoor giraffe run, houses the zoo's giraffe herd. Starting in the summer of 2015, guests can feed the zoo's giraffe herd at scheduled times throughout the day.

Mountain Sheep Habitat was opened in 1979. It contains two natural style "mountains" housing Dall sheep and bighorn sheep.

Hoofed animals elsewhere include red river hog and yellow-backed duiker, both in Primate Panorama.

Penguins outside the entrance to Bird World. Daily feeding shows help educate the public about the shy birds.


Nearly 200 bird species, many rare and endangered, are exhibited in Denver Zoo's bird facilities, all of which are located next to or in Primate Panorama.

Bird World, opened in 1975, features open aviaries in which guests can mingle with exotic birds such as Egyptian plovers, rhinoceros hornbills, scarlet macaws and even two-toed sloths. Each area features naturalistic habitats and replicated tropic and aquatic ecosystems, with three major exhibits built without barriers so the birds can fly freely among zoo visitors. At the Bird World kitchen viewing window, visitors can see firsthand what the birds eat. There are five outdoor exhibits directly attached to the exterior of Bird World which are home to African penguins, sea eagles, Egyptian vultures, Eurasian eagle owls, and double-wattled cassowaries.

The original aviary currently houses the bald eagle and Andean condor, and is the winter quarters for flamingos and scarlet ibis.

Lorikeet Adventure, the Nurture Trail, and the Bird Propagation Center opened in 2006 between Bird World and the Primate Panorama. Lorikeet Adventure is a large, open-air mesh tent where visitors can mingle with and feed lories and lorikeets. The Nurture Trail is a short trail through a forested glade home to two exhibits: one for red-crowned cranes and one for cinereous vultures. The trail then goes past smaller outdoor enclosures attached to the Bird Propagation Center, which provides the Denver Zoo with state-of-the-art facilities for breeding and raising all types of birds.

The Forest Aviary in Primate Panorama is a 7,500-square-foot (700 m2) area richly landscaped and enclosed in a nearly invisible wire mesh. Visitors can walk around inside with the birds, which include a black swan, black-necked swan, scarlet ibis (housed with the flamingos in the winter), Mandarin ducks, nene (or Hawaiian goose), and crested oropendola.

Humboldt penguins are housed north of Bear Mountain.

Along with these birds, peafowl roam the zoo, the parking lot, and the park outside.

Northern Shores[edit]

Northern Shores was opened in 1987 and features polar bears, North American river otters, California sea lions, and harbor seals. It was home to the famous polar bear cubs Klondike and Snow. Underwater viewing windows are provided in the polar bear and sea lion habitats.

Wolf Pack Woods[edit]

Wolf Pack Woods has been cleared to make way for the zoo's new tiger exhibit, expected to open in spring of 2016. Guests can see the zoo's two maned wolf packs at the Feline House or near the Hoofed Mammal yards.

Tropical Discovery[edit]

Tropical Discovery was opened in 1993. The building explores several tropical environments and displays mammals, reptiles, fish, amphibians and insects from these areas. The trip begins with a view into a South American river with different species of freshwater stingray then continues to a cave where guests are immersed within the community of several bat species including the vampire bat. A snake exhibit hidden inside a Mayan temple features several venomous species including the king cobra and eyelash viper. Other South American animals here include capybara, black howler monkey, arapaima, piranha and poison dart frog. Further on, visitors are immersed in an underwater coral reef with seahorse, clownfish, yellow tang, lionfish and moray eel. Around the corner, a gallery of North American snakes is located across from alligator snapping turtle and other North American reptiles and fish in a large pool. Further on, Siamese crocodile lurk in their pool amongst other Asian swamp species like snake necked turtles. The Komodo dragon exhibit was the largest of its kind at opening and is still one of the largest Komodo dragon exhibits in the country.[17]

Toyota Elephant Passage[edit]

One of the gibbon islands

Toyota Elephant Passage is a $50 million 10-acre (4.0 ha) exhibit. At its opening, it was the largest bull elephant habitat in the world, designed to house up to 12 elephants, 8 of them bulls. It houses Asian elephants and other animals such as the Indian rhinoceros, Malayan tapirs, and clouded leopards, which rotate among different habitats in the same style as Predator Ridge. The exhibit includes more than 2 miles (3.2 km) of trails for the animals, and pools in the exhibit contain a total of 1,100,000 US gallons (4,200,000 l). Gibbons swing directly over visitors, traveling between three islands. The exhibit includes an indoor facility for smaller species, and will provide breeding facilities for the Indian rhino and Asian elephant in North America.[2][28][31][32][33] The exhibit opened with two female elephants (Mimi and Dolly) and two bull elephants (Bodhi and Groucho).[14]

The exhibit will be powered with a gasification pyrolysis system scheduled online in December, 2015. The system is permitted as a Other Solid Waste Incinerator (OSWI). The OSWI will convert the zoo’s select animal waste and trash into what is termed as "syngas" or synthesis gas or synthetic gas to "power approximately 20% of total zoo energy needs, including residual heat that will be used to provide hot water needs within the new Toyota Elephant Passage (TEP) exhibit" (Engineering Design and Operations Plan (EDOP) Denver Zoological Foundation Waste To Energy System, 2014, p.5).

The exhibit and its buildings have received LEED Platinum certification from the U.S. Green Building Council.[31][34]

Other facilities[edit]

Endangered Species Carousel

The Endangered Species Carousel features hand-carved wooden replicas of some of Denver's most popular residents including a polar bear mom and cubs, giraffes, okapi and baby gorilla, along with many other endangered animals.

The Pioneer Train offers a quick trip around the zoo’s carousel meadow filled with beautiful lush foliage, under the shade of 100-year-old trees. Visitors can see American and Chilean flamingos and other waterfowl just outside the Primate Panorama exhibit. Denver Zoo’s Pioneer Train is the first natural gas-powered zoo train in the United States.

The Animal Hospital in Denver zoo was built in 1969.

The Gates Wildlife Conservation Education Center houses classrooms and meeting rooms for public and private (rental) use.

The Wild Encounters outdoor amphitheater is designed for wildlife presentations and is located just outside the Gates Center.

Education and conservation[edit]

Flamingo talk showcased Juvenile American flamingos during the summer of 2009

Throughout the day the Denver Zoo provides educational opportunities for visitors, including the sea lion demonstration, pachyderm demonstration, wildlife show, Wild Encounters, Predator Ridge demonstration, red river hog feeding, penguin feeding, Meet the Animal Stars, and others. Some of these are seasonal, and some (like the flamingo talk every day during the summer of 2009) showcase specific animals that have been raised at the zoo.

In 2014, a paid, mobile app titled the Denver Zoo Audio Tour became available, providing zoo visitors with the ability to hear short, educational presentations about numerous zoo animals.[35]

The Denver Zoo is part of the (American) Association of Zoos and Aquariums (AZA) Species Survival Plan for many species. As an active member of the World Association of Zoos and Aquariums (WAZA), Denver Zoo works with other zoos and aquariums around the world to respond to the global extinction crisis facing the world's frogs and other amphibians.

Denver Zoo's conservation efforts are coordinated by the Department of Conservation Biology. Through continued research and funding, the Department helps to conserve a variety of species worldwide. Although the zoo has been active in conservation and research since its founding in 1896, the establishment of the Department of Conservation Biology provides dedicated staff and funding to support hundreds of projects throughout the world.[36]

Recent successes in captive breeding at the zoo include:

Among many other notable mammal, reptile, amphibian and avian successes.


Boo at the Zoo is held every Halloween and is great fun for Children.

Zoo Lights is open during December evenings. This is a spectacular stroll through a wonderland of lights, many of them animated and representing animals at the zoo.


  1. ^ "Zoo Facts". Denver Zoological Foundation. Retrieved January 31, 2010. 
  2. ^ a b c d "Denver Zoo Annual Report 2013" (PDF). Denver Zoological Foundation. Retrieved September 2, 2014.  Cite error: Invalid <ref> tag; name "e_passage_animals" defined multiple times with different content (see the help page).
  3. ^ a b "Annual Report 2010" (PDF). Denver Zoological Foundation. Retrieved June 3, 2012. 
  4. ^ "List of Accredited Zoos and Aquariums". AZA. Retrieved December 31, 2010. 
  5. ^ "Zoos and Aquariums of the World". WAZA. Retrieved December 31, 2010. 
  6. ^ Kelley, Joanne (June 21, 2006). "Destination: Denver (Record number of overnight visitors came to city in 2005)". Rocky Mountain News. p. 1B. Retrieved June 3, 2012. 
  7. ^ a b "History". Denver Zoological Society. Retrieved 1 February 2010. 
  8. ^ a b c d e f g Noel, Thomas J. (1997). "7". Mile High City: An Illustrated History of Denver. Denver, Colorado & Encinitas, California: Heritage Media Corporation. ISBN 1-886483-10-8. Retrieved 27 June 2011. 
  9. ^ a b Etter 1995, pp. 59–64
  10. ^ Chaze, Elliott (December 22, 1949). "Scornful of Bars". The Owosso Argus-Press. Retrieved June 5, 2012. 
  11. ^ "Velox". 31st U.S. Infantry Regiment Association. Retrieved June 5, 2012. 
  12. ^ "Glory Days of the Rocky Mountain News – Jack Foster – A Remembrance of Velox". George in Denver. November 2, 2008. Retrieved June 5, 2012. 
  13. ^ "Velox Polar Bear". Find a Grave. Retrieved 6 June 2010. 
  14. ^ a b "All elephants at Denver Zoo in United States". Elephant Encyclopedia. Retrieved June 5, 2012. 
  15. ^ Etter 1995, p. 76
  16. ^ Asmar, Melanie (July 9, 2009). "Caution: A herd of bull elephants is coming to the Denver Zoo". Denver Westword. p. 2. Retrieved June 5, 2012. 
  17. ^ a b Etter 1995, pp. 186–189
  18. ^ Monaghan, Kelly (2007). "Sea World". The Other Orlando (4th ed.). The Other Orlando. ISBN 1-887140-66-2. 
  19. ^ Snow the polar bear dies unexpectedly at Tucson zoo at age 17, Denver, CO: The Denver Post .
  20. ^ "Polar bear Klondike dies at SeaWorld". The Denver Post. Retrieved 15 December 2013. 
  21. ^ Denver Zoo Sculpture Locations, Denver, CO: The Denver Zoo .
  22. ^ "Jaguar kills Denver zookeeper". The Denver Post. 2007-02-25. Retrieved 2007-02-25. 
  23. ^ "Denver Zoo Reviews OSHA Document on Jaguar Accident". Denver Zoological Society. Retrieved 1 February 2010. 
  24. ^ "Denver Zoo and City Work Together to Improve Duck Lake in City Park". States News Service. February 9, 2010. Retrieved January 5, 2014. 
  25. ^ Doligosa, Jr., Felix (August 8, 2006). "Zoo plans Asian animal exhibit". (The Rocky Mountain News). Retrieved June 5, 2012. 
  26. ^ Asmar, Melanie (July 9, 2009). "Caution: A herd of bull elephants is coming to the Denver Zoo". Denver Westword. p. 5. Retrieved June 5, 2012. 
  27. ^ "Denver Zoo Breaks Ground on 10‐acre Asian Tropics Exhibit" (PDF). Denver Zoological Foundation. Retrieved June 3, 2012. 
  28. ^ a b Asmar, Melanie (June 1, 2012). "Photos: Denver Zoo's $50M Toyota Elephant Passage opens today". Denver Westword. Retrieved June 3, 2012. 
  29. ^ "Zoo Map". Denver Zoological Foundation. Retrieved 31 January 2010. 
  30. ^ "Special Exhibits". Denver Zoological Foundation. Retrieved 31 January 2010. 
  31. ^ a b "Toyota Elephant Passage: Opening at the Denver Zoo, June 1, 2012". Visit Denver. Retrieved June 3, 2012. 
  32. ^ "Denver Zoo Opens $50M Elephant Exhibit". CBS News. Retrieved June 3, 2012. 
  33. ^ Draper, Electa (November 9, 2011). "Denver Zoo finishing world-class expansion for elephants and friends". Denver Post. Retrieved June 3, 2012. 
  34. ^ "Toyota Elephant Passage: Denver Zoo's New Asian-Tropics Themed Exhibit Opens Today". The Huffington Post. June 2, 2012. Retrieved June 3, 2012. 
  35. ^ "Denver Zoo Audio Tour". MyDenverTours. Retrieved 2 September 2014. 
  36. ^ "Conservation Overview". Denver Zoological Foundation. Retrieved 1 February 2010. 


  • Etter, Carolyn & Don (1995). The Denver Zoo: a Centennial History. Boulder, Colorado: Roberts Rinehart Publishers. ISBN 9781570980398. 

External links[edit]