Design a site like this with
Get started

The World Association of Zoos and Aquariums (WAZA) boasts over 700 million visitors to its zoos each year – including London Zoo (UK), Calgary Zoo (Canada) and hundreds of other institutions around the world. This makes them a huge asset in raising awareness for the environmental threats that animals face, whilst also generating substantial funds for conservation projects. But zoos are also subject to much criticism for a variety of reasons, particularly around animal welfare concerns. This post will investigate these concerns and the priorities of zoos, and answer the question: how do zoos decide which animals to keep?

The aim of zoos

There are over 10,000 zoos worldwide, involved in both ex-situ (within the zoo) and in-situ (in the wider environment) conservation activities (Tribe & Booth, 2003). These include education programs, captive breeding, habitat restoration, species re-introduction and research (Tribe & Booth, 2003), and have led to many species’ success stories around the world. For example, the Golden Lion Tamarin Conservation Program in Brazil saw the size of the wild population of these primates increase by 20% over 10 years after successful captive breeding and reintroduction activities (Tribe & Booth, 2003). Another more well-known example is the huge restoration of Californian Condors: numbering just 22 in the early 1980s, intense captive breeding efforts took place across several zoos in the state. As a result of this, there are now over 500 individuals, with the 1000th chick born last year (Weston, 2019).

California condor - Wikipedia
Handsome beastie, the Californian Condor. Source: wikipedia

It is therefore established that the main aim of zoos is to promote conservation of animal species, populations and habitats (Palmer et al., 2017). But if this were the case, zoos would comprise of species which are highly threatened, and where there is some likelihood of successful reintroduction to the wild – but this is not always the case. With limited space, the need to make money through maintaining high visitor numbers and because of the range of conservation activities which can be undertaken, deciding which animals to keep at a zoo is tricky (Palmer et al., 2017). For example, is it worth focusing on large mammals which are not necessarily the most in need of protection, in order to maintain visitor numbers and funds? Or would it be better to keep smaller mammals, amphibians and invertebrates of high conservation value and which use less resources, at the cost of media attention?

 “Zoos must operate tactically by using their collections to best serve their own conservation goals. But these will vary, depending on what conservation values are prioritized. First among these criteria are “conservation status” and “extinction risk in the wild.” – Palmer et al. (2017)

Conservation value and animal welfare

Animal welfare is another key concern of zoos and must be balanced with conservation priorities. But the quality of life for animals isn’t prioritised in the same way as conservation is – if it was, we would not see elephants being kept in relatively small pens when they might roam 200km in a day in the wild. Other ethical issues of keeping animals in conditions vastly different to their natural habitats remain, as well as moral considerations – for example, does animal welfare matter for species with no obvious sentience (ability to feel pain)?

Some animals kept in zoo collections – particularly invertebrates – may not have a welfare, at least in the sense of having subjective experiences or preferences. It still makes sense to talk about them performing “natural behaviours”, but there’s a question whether this matters in animals lacking sentience.” – Palmer et al. (2017)

Compromises must be made between the competing aims of conserving species, population or genetic diversity, maintaining animal safety and the moral obligation to maintain a high level of animal welfare and quality of life (Kreger & Hutchins, 2010). Going back to the elephant example: is it worth keeping elephants in cramped conditions in zoos, for the funds that they raise for elephants in the wild? Some may say that this sacrifice of the individual for the benefit of others in the wild is an example of ecofascism, when others might think it’s appropriate to preserve the “greater good” (Palmer et al., 2017) – but the example demonstrates how contentious the issue can be.

Elephants Will Never Belong in Zoos
This elephant doesn’t look like it’s having much fun. Source:

Charismatic mammals

Charismatic animals such as the elephant provide high “exhibit value” – this being the term to describe the power that an animal has in attracting visitors. It is widely believed that mammals with large body sizes are needed to attract visitors – in fact it has been found that an animal’s “beauty” and body size is a good predictor of whether it will be found in a zoo (Frynta et al., 2013). But in their detailed literature review on the topic, Palmer et al. (2017) found little evidence of significant negative impacts when zoos solely selected species ideal for direct conservation (rather than for charismatic value). Perhaps then it might be better in terms of both conservation and welfare to redirect focus from large mammals which require huge resources, towards the 183 less-known candidate species which receive very little resources but are still aesthetically pleasing for visitors (Smith et al., 2012).

The most effective strategy to combat the problem of limited space is without any doubt a shift away from the large charismatic mammals towards smaller species, particularly amphibians, invertebrates and some species of fish, which occupy less space, are relatively inexpensive to keep, have a high birth rate and are easy to reintroduce.” – Palmer et al. (2017)


In answer to the original question, zoos keep animals according to their conservation value, the degree of welfare and quality of life which can be maintained for them at the zoo, the financial and practical costs of keeping such animals and in some cases the charismatic appeal or popularity of species. Zoos remain an effective way of gathering public attention and funds and directing it towards conservation programs, but they must also exemplify high animal welfare standards, and refuse to keep animals which do not adapt well to confined conditions. One way through which this could be achieved would be to focus resources into smaller, less space and resource-intensive species of high conservation value, rather than keeping animals which cannot easily adapt to zoo conditions, and ensuring that animal welfare is prioritised alongside conservation.

Animal welfare belongs to each animal; it is not given to them. Zoos affect the degree of that welfare, but must balance it with their conservation objectives.” – Kreger & Hutchins, 2010


Frynta, D., Šimková, O., Lišková, S. & Landová, E. (2013) Mammalian collection on Noah’s ark: the effects of beauty, brain and body size. PloS one8(5), p.e63110.

Kreger, M.D. & Hutchins, M. (2010) Ethics of keeping mammals in zoos and aquariums. Wild mammals in captivity: Principles and techniques for zoo management, pp.3-10

Palmer, C., Kasperbauer, T.J. & Sandøe, P. (2017) Bears or butterflies? How should zoos make value-driven decisions about their collections? The Ark and Beyond: The Evolution of Zoo and Aquarium Conservation, pp. 179-191

Smith, R.J., Veríssimo, D., Isaac, N.J. & Jones, K.E. (2012) Identifying Cinderella species: uncovering mammals with conservation flagship appeal. Conservation Letters5(3), pp.205-212

Tribe, A. & Booth, R. (2003). Assessing the role of zoos in wildlife conservation. Human Dimensions of Wildlife8(1), pp.65-74.

Weston, P. (2019) Ten wildlife stories to sing about in 2019. [online] Available at: (14/11/20)

Read more about…

Scottish wildcats and captivity

Yellowstone National Park

Mutualism in nature


Published by avleveri

Hi! I'm Anna, an environmental science graduate from the UK. My main interests (if you can't already tell from my blog posts) are sustainability, consumption, conservation, nutrition, fitness and food! Lots of food.

Leave a comment

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: