Zoos behind bars – a vegan perspective on animal ethics, species conservation and alternatives

The question of freedom is the starting point.

Going to the zoo for the first time as a child can be magical: exotic animals up close, sweets in hand, curious glances. But the magic quickly fades when you see the tiger behind glass. Its enclosure is only about 200 m² in size ^[1] – that's how much space the official report recommends for one or two tigers. In the wild, tigers would occupy territories of up to 1,300 km² ^[1] . You can see the animal pacing back and forth, an endless loop on concrete.

Many people are familiar with such impressions: enthusiasm and irritation are closely intertwined. Zoos advertise with education, research, and species conservation, yet at the same time, animals are imprisoned, bred, traded – and, when they are no longer needed, killed ^[2] . For vegan animal lovers, young activists, and all those who seriously consider animal rights, the question therefore arises: Do we really need zoos?

What is a zoo? A brief history of captivity

Keeping exotic animals is not a new invention: as early as 5,000 years ago, rulers in Egypt and Mesopotamia maintained menageries as a sign of their wealth ^[3] . The first modern zoological gardens were established in the 19th century; the London Zoo opened in 1828, and the Berlin Zoological Garden in 1844 ^[3] . At that time, people were even exhibited in so-called ethnographic shows.

Today's zoos often emphasize four key areas of activity: conservation, education, research, and recreation ^[4] . They publish studies and participate in breeding programs. However, less than five percent of the approximately 8,500 species kept in European zoos are even considered threatened ^[5] . Conservation efforts often focus on high-profile species such as pandas or Przewalski's horses, while hundreds of other species are largely ignored.

Small cages – facts about keeping them

There are immense differences between the natural habitat of many wild animals and the enclosures in zoos:

• Polar bears: In Germany, polar bear pairs have at least 400 m² available ^[1] . In the wild, they roam regions between 20,000 and 250,000 km² and cover up to 80 km daily ^[6] . Biologist Hanno Würbel points out that all polar bears studied in captivity exhibit stereotypies ^[6] .
• Tiger: The minimum size for a tiger enclosure is 200 m² ^[1] ; in the wild their territories range from 20 to 1,300 km² ^[1] .
• Chimpanzees: At the Zoo am Meer in Bremerhaven, chimpanzees share an enclosure of 800 m² ^[6] . In the wild, they have territories of 50–70 km² ^[6] . A study of 40 chimpanzees in European zoos revealed that every single animal behaved abnormally – including eating feces or rocking back and forth for hours ^[5] .
• Elephants: A study from Wroclaw showed that a zoo elephant spent 52% of her day performing repetitive movements – three and a half times as much as her counterparts in other zoos ^[7] . In another study, three-quarters of the 84 Asian elephants in European zoos suffered from stereotypies such as head bobbing or standing in the same spot for extended periods ^[5] .

Such behavioral abnormalities – often referred to as “zoochosis” – indicate deep psychological distress. A meta-analysis of stress in captive wild animals concluded that prolonged captivity can lead to chronically elevated stress hormone levels, weight loss, weakened immune systems, and reduced reproductive capacity ^[8] . Many animals never fully adapt to artificial conditions ^[8] .

Pro Zoo: Species conservation, education, research?

Proponents point out that zoos breed endangered species, provide scientific insights, and raise awareness of nature conservation. Some successes are undeniable:

• Przewalski's horses: These wild horses were considered extinct in the wild by the mid-20th century. Thanks to international breeding programs, more than 2,000 animals now live again; approximately half have been reintroduced to Mongolia, China, and, since 2024, also to Kazakhstan ^[9] .
• Reintroductions from zoos to the wild: One study found that 32 out of 53 animal species that had survived exclusively in human care since 1950 were able to be released back into the wild – around 60% ^[10] .
• San Diego Zoo Wildlife Alliance: The organization states that, together with partners, it has successfully reintroduced more than 44 threatened species to their original habitats ^[11] .

Education or zoochosis? – A critical counter-argument

Zoo operators emphasize the educational value of their facilities: Millions of people visit zoos every year and are meant to experience animals up close ^[2] . But education doesn't have to take place behind bars. Nature documentaries like Our Planet or Serengeti show animals authentically in their habitats. Virtual and interactive offerings allow for intensive encounters without uprooting animals from their ecosystems.

Some studies suggest that zoo tours have short-term positive effects on environmental awareness ^[4] . However, critics see a “Disney effect”: animals are presented as harmless plush toys, while the causes of their decline – climate change, land grabbing, hunting – are ignored. Even the International Union for Conservation of Nature (IUCN) points out that the most effective species conservation lies in the preservation of habitats ^[15] .

Scandals and abuses – suffering behind the scenes

• In a study of 40 chimpanzees in European zoos, all animals showed abnormal behavior such as self-aggression or eating feces ^[5] .
• The Great Ape Project found that around half of the great apes studied in zoos showed symptoms of zoochosis ^[16] .
• At the Nuremberg Dolphinarium, dolphins had to be treated with diazepam and other psychotropic drugs ^[16] .

Alternatives: Protected areas, sanctuaries, and digital experiences

• Wildlife rescue centers and sanctuaries: take in injured or confiscated animals, do not breed them and do not trade them ^[15] .
• National parks and protected areas: They offer habitat protection and natural observation of animals in the wild.
• Virtual zoos and nature documentaries: enable digital experiences with animals without captivity.
• Support for in-situ projects: through donations and commitment to habitat conservation and wildlife protection.

Conclusion: Between compassion and show business

Zoos originate from a time when exotic animals were status symbols. Today they present themselves as rescue centers, but economic interests often dominate their operations. Individual successes such as the Przewalski's horse or the European bison ^[9][10] cannot disguise the fact that thousands of healthy animals are killed every year ^[2] . Education works without cages, and real species conservation begins with protecting habitats and ending exploitation.

Perhaps it is time to rethink our relationship with wild animals: they don't need us in zoos – we need them in an intact natural environment.

List of sources

1. National Geographic (2022): Minimum enclosure sizes and territories of tigers and polar bears.
2. Animal Welfare Association: Report on zoo culling and releases into the wild.
3. National Geographic: History of Zoological Gardens.
4. bpb.de: The four areas of responsibility of modern zoos.
5. National Geographic: Percentage of threatened species and studies on behavior.
6. Animals' Voices Bremen: Enclosure sizes, movement radii, expert opinions.
7. PubMed (2006): Study on stereotypical movements in elephants.
8. PMC (2019): Stress and health problems in wild animals in captivity.
9. DW.com (2024): Reintroduction of Przewalski's horses.
10. Earth Island Journal: Reintroduction of endangered species.
11. San Diego Zoo Wildlife Alliance: 44 species reintroduced into the wild.
12. National Geographic (2014): Marius the Giraffe at Copenhagen Zoo.
13. Ostsee-Zeitung (2025): Milu deer in Schwerin Zoo.
14. ZDF heute (2025): Baboons killed at Nuremberg Zoo.
15. Treehugger: Difference between Zoo and Sanctuary, focus on habitat conservation.
16. Animals United: Zoochosis, dolphin medication, ethical criticism.