The Houston Zoo (also known historically as the Hermann Park Zoo and the Houston Zoological Gardens) is a zoological park located within Hermann Park in Houston, Texas, United States. The zoo opened in 1922 as a park attraction housing 40 animals. In 2026 it housed around 4300 animals, and as of 2024 the collections included representatives of 575 species. The zoo had 2 million visitors in 2024.2024 Annual Report, 3.
The Houston Zoo participates in ongoing efforts to protect the endangered Attwater's prairie chicken and Houston toad, as well as supporting conservation organizations locally and globally. In 2026 this work included 52 conservation projects across 17 countries. In 2009 the zoo partnered with the Baylor College of Medicine to develop a vaccine for elephant endotheliotropic herpesvirus (EEHV), a disease affecting Asian elephants, which became available for use in captive populations in 2024.
The zoo has been managed and operated by the non-profit Houston Zoo Inc. since 2002. It was previously part of the city parks department. It is a member of the World Association of Zoos and Aquariums (WAZA), and is accredited by the Association of Zoos and Aquariums (AZA).
History
Early zoo and establishment in Hermann Park Houston's first zoo opened in 1901 in the city's downtown Sam Houston Park. Its animals, most of which were given to the zoo by individuals or civic groups, included a range of mostly American wildlife including black bears, prairie dogs, monkeys, opossums and eagles, as well as domestic species such as guinea pigs, goldfish and goats. The zoo closed abruptly in 1906 when the city's park commissioner sold the collection to another exhibitor and had the animals packed and shipped before notifying the public. He later cited the cost of maintaining the animals as his reason for closing the zoo. For the next fifteen years Houston had no public zoo.
Development of the current Houston Zoo began in 1921 when the federal government gave a bison from the federal herd at the Wichita Forest Reserve (Now the Wichita Mountains Wildlife Refuge) to the city of Houston. The bison, named Earl, arrived in March 1921 and was placed at then-new Hermann Park. The parks department purchased a female bison as a companion for Earl, began to build animal cages in the park, and called for help from the community in providing additional animals and raising funds to purchase more expensive specimens like "an elephant, zebra, camels, elks, lions, and other larger animals." Park superintendent Clarence Brock hired Hans Nagel, who had previously worked in Germany as a wild animal hunter and handler for Carl Hagenbeck, as assistant zookeeper.
The zoo officially opened on April 30, 1922. In 1923 Nagel was promoted to head keeper, a post he held until his death in 1941. By 1925 the zoo facility had been finalized as a 34-acre fenced area within the park, and its animal collection included 300 birds, 100 reptiles, and 400 other animals.Bradley, 143.
Zoo design and early development
In 1923 the Houston Board of Park Commissioners and Planning Commission hired landscape architects Hare & Hare to design the zoo grounds. Their design established the zoo's general shape and orientation as an oval divided at the north end by a series of three reflection pools (combined into a single pool in the 1950s) that formed an axis with the larger reflection pool near the main entrance to Hermann Park. The zoo entrance was placed at the north end of the oval facing into the park.
Hare & Hare's design provided guidance for exhibit placement as the zoo was built out. The city implemented some elements of the plan, including a sea lion pool opposite the entrance at the end of the reflection pool, a free-flight aviary, a performance arena for big cat shows, and space for the city's natural history museum, which was located on the zoo grounds from 1927 to 1969. Others were never built, including the proposed aquarium and the set of barless enclosures--a popular zoo design in the early twentieth century, separating animals from visitors with moats and artificial cliffs rather than cages--proposed for housing bears, canids, badgers and lynx.
The Houston-born writer David Westheimer later recalled that when he was a child in the 1920s, "nearly all of the animals in the Hermann Park Zoo were in iron-barred cages, and not very big ones. The elephants, Hans (named after zookeeper Hans Nagel) and Nellie, were in a stockade, and I think the giraffes were too. The four-footed grazing-type creatures were merely fenced in, and nothing had been done to make their domain resemble anything but an undersized and overcropped pasture."
Access Under Houston's Jim Crow laws, African Americans were allowed to visit the zoo, although the municipal code segregating the park system otherwise designated Hermann Park for whites. Facilities such as water fountains and restrooms within the zoo were segregated into the 1950s.Elliott, Lynne S., "One Woman's Saga--50 Years of Civil Rights and Racial Prejudice" (Honors Thesis, Southern Illinois University-Carbondale, 2001), 1-2. http://opensiuc.lib.siu.edu/uhp_theses
Entry to the zoo was free, and with the exception of a two-year period during the Great Depression, it remained free until the beginning of 1989.
Early years, 1920s-40s
From its opening in 1922 through the end of World War II the zoo was a recreation and entertainment amenity for the city, which was a common approach to zoo management at this time. In 1925, park superintendent Brock explained to the Houston Chronicle that a zoo could be planned either as a scientific exhibit or as a menagerie, and "ours will lay stress on the menagerie idea. We will have trained animals to perform as well as specimens for folks to look at, and we'll select our specimens for their popular interests first and their naturalistic interest second."Wallisch, Rebecca (2023). "Statement of Historic Contexts," National Register of Historic Places Multiple Property Documentation Form for Historic Buildings and Structures of the San Antonio Zoo, p. 3. Head keeper Nagel gave regular circus-style performances with the zoo's big cats in the arena built for that purpose. There were also demonstrations of alligator wrestling and performing chimpanzees, and at times staff allowed visitors to handle baby animals.Building a Zoo for All, 22. In the early 1940s the zoo was nationally known for its collection of albino specimens of common Texas wildlife, which included a bobcat, a vulture, a flying squirrel, an opossum, and a pair of raccoons.
After the initial investment, the zoo's budget from the city did not include funds for purchasing new animals. It relied instead on a combination of donations, fund-raising campaigns for big-ticket purchases like elephants, captive breeding, and trading of specimens with other zoos. Brock and Nagel also undertook collecting expeditions to capture new animals for the zoo.Building a Zoo for All, 15, 20.
In 1928 the zoo became part of the first American effort to protect a threatened species, other than a mammal or a bird, when it received a group of Galapagos tortoises from the New York Aquarium. The Aquarium collected the tortoises in the Galapagos Islands and was distributing them to other zoos in an effort to protect the species through establishment of a captive population and breeding program.Building a Zoo for All, 14. Three of these animals still live at the zoo as part of the tortoise herd in the Galapagos Islands exhibit.
Depression-era deterioration While some of the original buildings, including the monkey house and the free-flight aviary, were designed to be permanent, many of the original structures were made of recycled materials. The first big cat arena, later replaced by a permanent facility, was made of old bars from the city jail, and other buildings including the big cat house, chimpanzee house, and restrooms were repurposed from the World War I-era Camp Logan and were meant to be temporary.
The Great Depression severely restricted zoo funding. In 1932, after a reduction of $15,000 in its budget (calculated by MeasuringWorth as equivalent to at least $280,000 in 2024 dollars), an admission fee of 10¢ for adults and 5¢ for children was established, lasting into 1933. The charge was presented to the public as an alternative to raising money by selling off the animals. Without money for maintenance the makeshift buildings deteriorated, leading to animal escapes and other dangerous situations. In 1934 a 600-lb lion named Hermann fell through the rotted floor of his cage. This demonstration of the building's unfitness led the zoo to apply for a grant from the Works Progress Administration (WPA) for a new lion house, which opened in 1937. Other escapes included a grizzly bear that clawed its way out of a building weakened by dry rot and was shot, and a young chimpanzee that escaped by tearing out the rotted window frame in its building. In addition to these incidents, critics noted that the buildings weren't fireproof, adding risk for animals, keepers and visitors. The zoo did not receive funding from the city to correct these deficiencies or make other updates until after World War II.
Mid-twentieth century expansion
In 1947 the city of Houston again hired Hare & Hare to develop an updated zoo design. In 1948, following a review of potential sites in other city parks, city leaders decided to keep the zoo in Hermann Park and expanded its footprint from 34 to 43 acres of parkland. The zoo added a series of new or updated exhibits, including a new primate house (1950), a new sea lion pool (1951) to replace the original pool demolished to build the primate house, an upgraded elephant barn and yard (1952), a new reptile house (1960) and a new small mammal house (1961).Building a Zoo for All, 23, 30. These buildings were in the "sanitary modernist" style that was common in mid-twentieth century zoo architecture. Made of concrete, tile and glass, they housed animals in "sleek, easy-to-clean concrete boxes."Wallisch, 8. Zoo design soon began to swing away from this aesthetic, and the buildings completed later in the 1960s and in the 1970s, including a tropical bird house (1966) and a gorilla exhibit (1973) began to introduce plants and water features to evoke aspects of the animals' natural environments.Baratay and Hardouin-Fugier, 272.Building a Zoo for All, 32, 40.
In 1956 the zoo hired its first professional staff, a veterinarian and a curator. John Werler, the curator, was a herpetologist and the former assistant director of San Antonio's Brackenridge Park Zoo. He became the zoo's first director in 1963, succeeding head keeper Tom Baylor who had been Hans Nagel's deputy and took over after Nagel's death. In 1957 Werler, who had established the first zoo collection of vampire bats in San Antonio, collected more bats in Mexico to establish a colony in Houston, which would become the first breeding zoo colony of vampire bats. They remained on display until 2008; the colony was rehomed because the slaughterhouses that had provided fresh blood for the bats had closed and the zoo was left without a reliable source of food for the colony.Building a Zoo for All, 28.
In 1968 the first children's zoo opened, supported by bond funds for infrastructure and a $200,000 fundraising campaign for exhibits (calculated by MeasuringWorth as equivalent to at least $1.89 million in 2024 dollars). Designed for three- to six-year-old children, it included a harbor seal pool with underwater windows and an animal nursery with a viewing window. The petting zoo had four zones designed to evoke North America, Latin America, Asia and Africa.