A Zoo Study

[amur leopard]

The past few weeks I have been working on quite a large project. The aims of the project were thus:

• To, with some degree of accuracy, determine the percentages of the species found in zoos of different levels of endangerment.
• To, with the data obtained to achieve the above bullet point, compare two continents (North America and Europe) once all the data has been collected in the above regard, as well as drawing comparisons on a zoo-to-zoo basis.
• To, again with the same data, investigate the proportions of different classes found in zoos and compare it to the natural average (in the wild)
• And finally to take all the data collected and use it to compare zoo's percentages with the wild's percentages and hence conclude as to whether zoos are carrying out the conservational work they pledge to do.

Of course, the final bullet point is highly subjective and is down to a lot of different factors, but if the study finds that, for example, the percentage of critically endangered species in zoos is in fact lower than that of the wild, it would raise questions as to why this is the case. If the aims are confusing, I will explain them in more detail as we go on.

Every post will deal with each bullet point in turn. As I have not entirely completed the data for North American zoos, only the European zoos' data will be available for use for the moment.
Of course, there are a few caveats as always with this kind of study:

• I will be using Zootierliste for European zoos and species lists written on this website for American zoos to collect data on the endangerment of the species in zoos. While neither are entirely reliable sources of information, based on previous calculations the study would be swayed by ±0.1% on the final figures given the likely unreliability of these sources.
• There might be a degree of human error involved. I have counted and sifted through large lists - I may have missed one or two species during the data collection stage. This shouldn't influence the study much, but is still something to be aware of. I also had to plug the collected data into an Excel document with pre-prepared functions. Minor errors may have been made in this process. The document was then copied and pasted into a Google Sheets document to make it easier to share.
• There is a slight issue with comparing the wild averages and the zoo averages in that in the case of the zoo, I am issuing the percentages zoo-by-zoo meaning there will be species repetitions when the zoo data is looked at across all the zoos analysed. In contrast, the wild averages deal with different species with no repeats. However, unless level of endangerment affects number of holders drastically, this shouldn't be a problem.

So, having looked through the caveats and concluded that there is nothing that could drastically affect the results of the study, here are the results regarding bullet point 1.

1. This bullet point will concentrate on European zoos for now, and the results will later be compared to North American zoos to see if there is any difference. The 13 European zoos that were used for the data were the following:

• Chester Zoo
• ZooParc de Beauval
• Zoo Berlin
• Tierpark Berlin
• Colchester Zoo
• Zoo Leipzig
• Zoo Zurich
• Zoo Wroclaw
• Zoo Praha
• Zoo Plzen
• Pairi Daiza
• Diergaarde Blijdorp
• Tiergarten Schoenbrunn

These were all selected because they are relatively high profile zoos who were all likely to have relatively high numbers of species in each class, meaning they are more applicable to the study.
While Colchester Zoo may seem a strange inclusion, it was added in due to time constraints but also to eliminate anomalies.

The classes included in the study were Mammals, Birds and Reptiles and Amphibians. Fish were omitted for several reasons:

• Reliable information on fish holdings in zoos is hard to come by due to a number of reasons.
• Not many fish species have been assessed by the IUCN.
• There is high variation in the number of fish species held in different zoos depending on whether or not they have a facility focusing on them

IUCN standard levels of endangerment have been used and abbreviated to make the data more readable in both the full data table and the summary below. Data Deficient and Not Evaluated were clumped together into one group. For now, I will only go over each zoo overall, but in subsequent posts I will give the more in-depth data relating to each zoo and each class within them.
So, here are the results:

Chester Zoo

DD/NE: 3.9%
LC: 45.6%
NT: 8.2%
VU: 13.4%
EN: 16.4%
CR: 12.1%
EW: 0.3%

ZooParc de Beauval

DD/NE: 9.5%
LC: 48.1%
NT: 10.2%
VU: 11.2%
EN: 12.1%
CR: 9.0%
EW: 0%

Zoo Berlin

DD/NE: 3.2%
LC: 62.8%
NT: 9.4%
VU: 10.8%
EN: 9.6%
CR: 3.8%
EW: 0.4%

Tierpark Berlin

DD/NE: 5.9%
LC: 49.9%
NT: 11.8%
VU: 14.6%
EN: 10.4%
CR: 7.2%
EW: 0.2%

Pairi Daiza

DD/NE: 4.9%
LC: 54.9%
NT: 7.2%
VU: 15.3%
EN: 9.5%
CR: 7.2%
EW: 0.9%

Zoo Zurich

DD/NE: 2.6%
LC: 60.8%
NT: 6.7%
VU: 11.3%
EN: 12.9%
CR: 5.2%
EW: 0.5%

Colchester Zoo

DD/NE: 5.1%
LC: 40.9%
NT: 7.3%
VU: 19.7%
EN: 16.8%
CR: 10.2%
EW: 0%

Tiergarten Schoenbrunn

DD/NE: 5.0%
LC: 59.1%
NT: 6.6%
VU: 11.6%
EN: 11.2%
CR: 5.8%
EW: 0.8%

Zoo Wroclaw

DD/NE: 11.3%
LC: 54.2%
NT: 6.9%
VU: 12.3%
EN: 10.5%
CR: 4.5%
EW: 0.4%

Diergaarde Blijdorp

DD/NE: 2.7%
LC: 51.6%
NT: 8.0%
VU: 10.7%
EN: 12.9%
CR: 14.2%
EW: 0%

Zoo Praha

DD/NE: 6.8%
LC: 59.8%
NT: 8.4%
VU: 10.4%
EN: 9.1%
CR: 5.3%
EW: 0.2%

Zoo Plzen

DD/NE: 4.6%
LC: 68.8%
NT: 6.8%
VU: 9.6%
EN: 6.8%
CR: 3.2%
EW: 0.3%

Zoo Leipzig

DD/NE: 4.3%
LC: 57.3%
NT: 3.9%
VU: 10.2%
EN: 15.3%
CR: 8.6%
EW: 0.4%

So, on average in major European zoos:

5.68% of species are either Data Deficient or Not Evaluated
56.10% of species are Least Concern
9.18% of species are Near Threatened
11.69% of species are Vulnerable
10.62% of species are Endangered
6.41% of species are Critically Endangered
And 0.32% of species are Extinct in the Wild.

Here is my data table for European Zoos:

Zoo Study 1

I will draw some conclusions and rankings based on this information in the next post.
Sorry about the overload of data. At first I was thinking about going all in and including class-specific data in the first post but later decided that that will follow later .

 

[amur leopard]

Bullet Point 1: European Zoos Endangerment ranking

There is a big caveat to the listings below: the number of species in the zoo affects the rankings. For example, Colchester, the zoo which clearly had the fewest species of the lot with only 137 species in the classes analysed, while Plzen has a stunning 761. However, it is easier to have more endangered species if the zoo has fewer species, which is of course the case with Colchester. Therefore the rankings are to be taken with a pinch of salt.
Of the European zoos analysed in the study:

Here is the list ordered by species in the classes concerned:

1. Zoo Plzen (761)
2. Zoo Praha (604
3. Zoo Berlin (530)
4. Zoo Wroclaw (506)
5. Tierpark Berlin (459)
6. ZooParc de Beauval (412)
7. Pairi Daiza (346)
8. Chester Zoo (305)
9. Tiergarten Schoenbrunn (259)
10. Zoo Leipzig (255)
11. Diergaarde Blijdorp (225)
12. Zoo Zurich (194)
13. Colchester Zoo (137)

Here are the zoos with the greatest proportion of Vulnerable animals:

1. Colchester Zoo
2. Pairi Daiza
3. Tierpark Berlin
4. Chester Zoo
5. Zoo Wroclaw
6. Tiergarten Schoenbrunn
7. Zoo Zurich
8. ZooParc de Beauval
9. Zoo Berlin
10. Diergaarde Blijdorp
11. Zoo Praha
12. Zoo Leipzig
13. Zoo Plzen

Here are the zoos with the greatest proportion of Endangered animals:

1. Colchester Zoo
2. Chester Zoo
3. Zoo Leipzig
4. Diergaarde Blijdorp
5. Zoo Zurich
6. ZooParc de Beauval
7. Tiergarten Schoenbrunn
8. Zoo Wroclaw
9. Tierpark Berlin
10. Zoo Berlin
11. Pairi Daiza
12. Zoo Praha
13. Zoo Plzen

Here are the zoos with the greatest proportion of Critically Endangered animals:

1. Diergaarde Blijdorp
2. Chester Zoo
3. Colchester Zoo
4. ZooParc de Beauval
5. Zoo Leipzig
6. Pairi Daiza
7. Tierpark Berlin
8. Tiergarten Schoenbrunn
9. Zoo Praha
10. Zoo Zurich
11. Zoo Wroclaw
12. Zoo Plzen

However, having looked at the endangerment lists, a few things jump out at a glance. Plzen, the zoo with the largest collection by a margin, is always last by a margin, while Colchester, the smallest zoo by a margin, is top on two and third on the other. This suggests that these results aren't fair, but leads to the first conclusion:

The size of the collection affects the endangerment of the species within it; the larger the collection, the lesser the percentage of rare species.

Therefore, to attempt to make a more reliable ranking of the zoos, I weight the zoos according to their size. I therefore multiply the DD/NE and LC percentages by 1, the NT and VU percentages by 2 and the EN, CR and EW percentages by 3. I then multiply the collections by the square root of the factor by which their collection is larger than Colchester's. This leaves the following rankings, which ,while not absolutely accurate, are certainly much closer to the reality than the previous rankings:

1. Zoo Plzen (323.1)
2. Zoo Praha (310.8)
3. Tierpark Berlin (296.5)
4. Zoo Berlin (290.7)
5. Zoo Wroclaw (288.5)
6. ZooParc de Beauval (283.9)
7. Chester Zoo (267.2)
8. Pairi Daiza (250.5)
9. Zoo Leipzig (241.2)
10. Diergaarde Blijdorp (221.7)
11. Tiergarten Schoenbrunn (211.6)
12. Zoo Zurich (184.7)
13. Colchester Zoo (181.0)

It must however be noted that these rankings are remarkably similar to the species number rankings posted earlier, so perhaps the species number factor is too strong. I will work on a new formula to make it more realistic.

 

[Giant Panda]

You’ve raised some important questions. If you’re interested, published research already (broadly) answers them.

Zoo animals are disproportionately large, charismatic, and non-threatened. From a 2014 study: “Using data from 550 high-quality zoos worldwide, we identified 165 mammal and 228 bird species held in zoos that could be paired with clearly identifiable closest relatives not currently held in zoos. These matched pairs were then compared for threat level, zoogeographical distribution (including global hotspot endemism), spatial range, body mass, island habitat and altitudinal range. Results indicate that mammal and bird species in zoos are, on average, not only larger than their close relatives not held in zoos, but also possess larger spatial ranges, are less likely to be endemic and are distributed in lower-risk geographical regions. Importantly, they also tend to be less, rather than more, threatened with extinction.” Also, even accounting for conservation status, island and montane species were underrepresented (and both are disproportionately threatened by climate change). This taxonomic bias is compounded by the fact that most zoo populations of threatened species are unsustainable anyway.

Personally, I don’t think that percentage of threatened taxa kept is a useful measure of how much zoos contribute to conservation. A zoo is about the worst place imaginable to keep animals for eventual reintroduction (with exceptions); there is slim to no evidence that seeing a rarity inspires visitors to meaningfully contribute to its conservation; and zoos will never have the capacity to keep most threatened species. Resources allocated to in situ habitat conservation are more important – and funded by visitors who pay to see charismatic, non-threatened megafauna.

Reference: Martin, T. E., Lurbiecki, H., Joy, J. B., & Mooers, A. O. (2014). Mammal and bird species held in zoos are less endemic and less threatened than their close relatives not held in zoos. Animal Conservation, 17(2), 89-96.

Therefore, to attempt to make a more reliable ranking of the zoos, I weight the zoos according to their size. I therefore multiply the DD/NE and LC percentages by 1, the NT and VU percentages by 2 and the EN, CR and EW percentages by 3. I then multiply the collections by the square root of the factor by which their collection is larger than Colchester's. This leaves the following rankings, which ,while not absolutely accurate, are certainly much closer to the reality than the previous rankings

Any such collection size "weighting" will be arbitrary. You're investigating the percentage of threatened species, but giving zoos a free pass for keeping vast numbers of non-threatened species. Why?

 

[Dassie rat]

Hello Amur Leopard

Well done for compiling the figures. I realise how much time and effort goes into producing this kind of work.

Your studies show the high percentage of 'Least Concern' animal species kept in many zoos. If one of the main remits of zoos is to save endangered animals from extinction, why are so few of the animals in many zoos endangered?

 

[amur leopard]

Zoo animals are disproportionately large, charismatic, and non-threatened. From a 2014 study: “Using data from 550 high-quality zoos worldwide, we identified 165 mammal and 228 bird species held in zoos that could be paired with clearly identifiable closest relatives not currently held in zoos. These matched pairs were then compared for threat level, zoogeographical distribution (including global hotspot endemism), spatial range, body mass, island habitat and altitudinal range. Results indicate that mammal and bird species in zoos are, on average, not only larger than their close relatives not held in zoos, but also possess larger spatial ranges, are less likely to be endemic and are distributed in lower-risk geographical regions. Importantly, they also tend to be less, rather than more, threatened with extinction.” Also, even accounting for conservation status, island and montane species were underrepresented (and both are disproportionately threatened by climate change). This taxonomic bias is compounded by the fact that most zoo populations of threatened species are unsustainable anyway.

First of all, thank you for such a long and thorough answer. The study you have cited seems very interesting and is very pertinent to this particular conversation. Of course, while zoos can't really replace lions or elephants, it would be preferable, say, to replace a Red deer with a Tufted deer.

However, what, realistically, is the impact of the Tufted deer being in captivity instead of the Red deer? A breeding pair may produce, one perhaps even two offspring, but is the money spent moving the red deer out, re-purposing the exhibit and moving the Tufted deer in as well as the money spent on their husbandry on a yearly basis for the time they are in the collection better spent elsewhere? I am far from knowledgeable in the realm of exhibit and husbandry costs but I suspect the cost of doing all the tasks listed above is on par with a good deal more done in situ. Furthermore, positive feedback in situ can mean that a small change in the environment amplifies itself and can improve the area for the deer. As you say, because of these reasons I agree with you that in situ conservation is more effective than ex situ.

Having said this, I did this study less to whether zoos are doing enough for conservation but rather whether zoos have enough endangered species in their care to 'justify' their existence in the eyes of people who are against them, for it is this group of people who will not look beyond the surface and not see the nuance involved, but rather choose to look at their public image.

And while zoos (or rather captive breeding in some cases) have of course saved a number of species from extinction, a rather shallow 'animal rights' person will probably find, as I did, that there are far more Least Concern animals in zoos than any other group, and that in some cases, over half of the species in a zoo are not at all endangered.

Of course, conservation is not the only aim of a zoo; they are educational facilities conducting or allowing essential research as well, as well as being, dare I say it, a leisure attraction where people can spend a nice day out (which is the role they serve for many). But I still think that, after enclosure quality, the level of endangerment of the species in a zoo will be the second thing an anti-zoo person (for want of a better phrase) will check up on to assemble evidence, and this makes it an area where zoos might want to improve, whether it does brighten the future for these species or not.

At any rate, I think the percentage of Critically Endangered amphibians in zoos should certainly be higher given the percentage in the wild and given they breed often quite readily and are relatively easy to keep. But yes, you raise a very pertinent point there and I think in situ conservation is often more important than maintaining a captive population of a species.

Any such collection size "weighting" will be arbitrary. You're investigating the percentage of threatened species, but giving zoos a free pass for keeping vast numbers of non-threatened species. Why?

Hehehe now you put it like that...
Yes, I am a little guilty of wriggling around with my weightings to make the results a little more 'correct'
I think it is a little unfair to compare zoos who have relatively few species to the mega zoos with several hundred, and while I am of course at fault for adding in Colchester, Zurich and Rotterdam don't have too many species either and are pretty major. I was just trying to get nearer to a 'like for like' comparison, but of course, as you say, this type of thing is always arbitrary.

Again, thanks for you examination of my at times flimsy arguments and weightings - it is very helpful and I hope to improve in this respect, especially since I am going into science in the future for a job.

 

[amur leopard]

Hello Amur Leopard

Well done for compiling the figures. I realise how much time and effort goes into producing this kind of work.

Your studies show the high percentage of 'Least Concern' animal species kept in many zoos. If one of the main remits of zoos is to save endangered animals from extinction, why are so few of the animals in many zoos endangered?

As Giant Panda said, a large part of the conservation work zoos conduct is in situ, which is arguably more effective than captive breeding. Of course, not having many endangered animals may look bad when one examines the zoo away from it's in situ conservation efforts, but it is important to recognise that this important work is going on in the meantime and that the zoo's influence reaches far further than the land it sits on.

You do raise an important question, and I feel that a lot of space is wasted in zoos in favour of common megafauna, but is it worth the cost to exchange these animals with rarer equivalents? It is difficult to tell. I feel that the question of endangerment in zoos is especially important when it comes to amphibians, since quite a large percentage of species in that class are endangered and in need of captive breeding programs. of course we would like to see more endangered species, but it is important to recognise that it might not be a good step for the zoo economically as well as in the educational sense.

 

[Jurek7]

The size of the collection affects the endangerment of the species within it; the larger the collection, the lesser the percentage of rare species.

I suggest that from the point of conservation, what matters is absolute number of rare species and individuals kept, not their proportion.

Another thing, you could divide species into large and small mammals, birds, reptiles, amphibians, fish and invertebrates.

Currently your calculations punish zoos which have small animal collections. A zoo which has, say, a large breeding centre of endangered apes (3 species, 50 individuals) and also a fish tank which can easily house 20 common fish species, 150 individuals would come as a collection uncaring for conservation.

 

[amur leopard]

I suggest that from the point of conservation, what matters is absolute number of rare species and individuals kept, not their proportion.

I think it is a balance of the two. A zoo that keeps three endangered species should not be punished for having 100% endangered species in their zoo, and nor should 'postage stamp' collections (not saying Plzen is one) be punished for having lots of least concern as well as endangered species. What is also important in the conversation is potential. For example, take Leipzig. They have the potential to house rarer, less charismatic species in a way that a small zoo doesn't, but instead they've used it to house a pair of alpacas. Should they be rewarded for not using their space to house endangered species just because they are a big zoo?

With Leipzig, especially, I got the feeling that they weren't really trying to incorporate endangered animals. Their rare animals are almost all megafauna, like black rhinos, Asian elephants, Amur tigers, Amur leopards, gorillas, orangutans, chimpanzees, even lions and cheetahs. There are a few exceptions (pangolins etc.) but this kind of zoo feels different to a zoo like Chester or Prague where the endangered species are there because they are endangered rather than to make the zoo money. A good example of this is the Giant salamander house in Prague.

Another thing, you could divide species into large and small mammals, birds, reptiles, amphibians, fish and invertebrates.

On my spreadsheet I have divided it up into mammals, birds and herps. Didn't include fish and invertebrates for the reasons stated in the first post (the fourth column of bullet points).
I will divulge the more in-depth mammal, bird and herp percentages later on.

Currently your calculations punish zoos which have small animal collections. A zoo which has, say, a large breeding centre of endangered apes (3 species, 50 individuals) and also a fish tank which can easily house 20 common fish species, 150 individuals would come as a collection uncaring for conservation.

Aha, but I'm not including fish
But seriously, isn't this contrary to what you said in the first paragraph of your post. You said that it should be based on absolute numbers. But taking your example, the zoo would only have 3 compared to, for example, Beauval's 37. That doesn't make it fairer...

My rankings are entirely arbitrary, and entirely useless from a scientific point of view. The square root in the calculation represents nothing but an attempt to lessen the size facotrs importance. If I were to cube root it, it would lessen the size factor even more, but wouldn't take me close to a 'correct' answer because in truth, there isn't one. It's pretty much subjective, under the influence of at least ten different factors. The scale of the in situ conservation the zoo conducts is being ignored in this study. So is the how targeted that in situ conservation it, as well as the extent to which the zoo's signage makes it likely for the visitor to read it and learn something. Hopefully I have already explained why I am somewhat bluntly ignoring these factors; it is because from the point of view of someone who is against zoos and who is not willing to dive below the surface and learn more for fear of being dragged in, they see:

1. The enclosure quality.
2. And then the number of endangered animals
3. And then whether the animals look happy or not.

And of course these points are not quantifiable. You can't measure them in number of species, enclosure size, number of toys or how many smiles you see. The last one is downright impossible to tell from the point of view of the average visitor - every beluga and dolphin constantly looks overjoyed while you can't say Gaur ever look happy really.

Anyway, I'm not sure how I would be able to begin a fair investigation of how many a zoo has of each species. For starters, my American numbers are totally based off of species lists concocted here. There is little to no information on the number of a certain species at American zoos here beyond megafauna. Even Zootierliste hardly has information on animal numbers beyond large mammals and birds. Hopefully I have answered your question satisfactorily

 

[Dassie rat]

A zoo is about the worst place imaginable to keep animals for eventual reintroduction (with exceptions); there is slim to no evidence that seeing a rarity inspires visitors to meaningfully contribute to its conservation; and zoos will never have the capacity to keep most threatened species.

That is very interesting, Giant Panda. I agree that it is difficult to reintroduce large zoo animals into the wild. One of the big problems would be that the animals associated people with food and may be a risk to local people or their livestock? If your comments about seeing rare species does not tend to inspire people to conserve them, is there any point in keeping the species in zoos as well as conserving them in situ? There have been recent debates about euthanasia in zoos. In the wild, species with large litters will usually lose many of their young. In zoos, the survival rate of the young is higher. While some zoos will kill excess young, there is an ethos of 'some species being better than others'. If the zoo doesn't have enough space for the growing young, it will try and send it to other zoos, so the number of some species grow at the expense of other species. What is the point of this if few visitors want to save the species in the wild, while many of the displaced species could be reintroduced into the wild, but are not being saved in situ or ex situ?

 

[DDcorvus]

For European species, which listing did you use. IUCN makes a difference between Europe and global in their redlists. And some species which globally are Least Concern are in need of conservation in Europe. Common Hamster being such an example, Atlantic Puffin being another or more relevant for the UK zoos: Wild Cat which in the UK has a clear need for ex-situ support, but is not endangered globally (or even in Europe). Wolves might be another example where some subspecies might need support but the species itself is not endangered (and also brings in the discussion on the added value of the species for education in stead of conservation).

 

[amur leopard]

For European species, which listing did you use

I used Zootierliste, which is probably the most accurate way of doing it even though it has its flaws.

IUCN makes a difference between Europe and global in their redlists. And some species which globally are Least Concern are in need of conservation in Europe.

I just used global. Of course there are populations of certain species which need conservation initiatives (griffon vultures in Cyprus and Spain for example), but while this is important, it wouldn't make much difference to the study and would be affected by hybrids etc. where the many of the specimens are not purely of a single population but rather the result of lots of populations interbreeding.

 

[DDcorvus]

I used Zootierliste, which is probably the most accurate way of doing it even though it has its flaws.



I just used global. Of course there are populations of certain species which need conservation initiatives (griffon vultures in Cyprus and Spain for example), but while this is important, it wouldn't make much difference to the study and would be affected by hybrids etc. where the many of the specimens are not purely of a single population but rather the result of lots of populations interbreeding.

I understand the challenge, but I have to disagree as it would make a big difference. You are undervaluing the ex-situ conservation work of zoos. With your approach you miss a key component where in-situ and ex-situ come together and Europe might be a bit particular here as many species have ranges way beyond the continent while being threatened inside. At the same time it is a crucial field where European zoos are making a difference also beyond the charismatic species. Also hybrids are not so much the issue here.

 

[amur leopard]

Here are a few more class-specific stats. I will compare the captive percentages with the wild percentages and see the variation within the classes.

Mammals

Captive percentages pie chart:



Wild percentages pie chart:



The first thing that jumps out at a glance is that there are far more Data Deficient or Not Evaluated species in the wild than there are in captivity. There are two possible explanations for this, the second being the more likely one. Either research conducted by zoos has led to an increased knowledge about the species concerned leading to those species being evaluated by the IUCN or zoos have taken in more well-known animals because Data Deficient mammals are often not very charismatic and are found in secluded areas of the globe, hence the difficulty of evaluating their population.

The next most obvious difference is that in Endangered animals. While in the wild, there are more vulnerable mammals than endangered mammals, the opposite is true in zoos. This may well be due to many popular megafauna species being endangered, such as the Amur tiger, the Chimpanzee and the Red panda. There are also a good deal fewer Least Concern species in zoos. Nonetheless, it would still be telling for somebody with an anti-zoo disposition (getting more and more desperate for a description of one of said people ) that just under half of zoo mammals are Least Concern.

Generally, in terms of mammals, there are comparatively far more vulnerable, endangered and critically endangered mammals than in the wild. This is almost to be expected, and although some may be disappointed at the high number of LC mammals, zoos seem to be in a good place in this respect.

Birds

Bird percentages in captivity:



Bird percentages in the wild:



First impressions: Slightly fewer LC birds in zoos, and more CR, EN and VU. To be expected in a sense. However, still over 70% of captive birds are Least Concern. When compared to the wild figures, these don't seem bad, but in this particular class, zoos could do with some improvement. While of course some endangered bird species are difficult, if not impossible to keep in captivity, many are very similar to their more common relatives, who are in many cases, found widely across the world in zoological collections. This suggests that the problem lies more in acquiring the rarer species. With birds rather unfortunately being considered as 'filler' species in many zoos, does the problem lie in the rare birds not bringing in enough money to pay for themselves? As a zoo enthusiast I would prefer not to think so, but what other explanation is there?

Reptiles and Amphibians

R+A percentages in zoos:



R+A percentages in the wild:



This is possibly the class with the most similar charts. Slightly lower LC in zoos but higher NT, VU and CR. However, strangely, the percentage of endangered species is higher in the wild. This is slightly worrying.

Overall, looking over the graphs as a whole, there is a general trend. The mammal charts have the most variation between them, while the herp charts have the least. This while it may just be a coincidence, suggests that zoos are not pointedly importing endangered herps as frequently as endangered mammals. This, while understandable (megafauna brings in most of the money for zoos), is a little worrying, Herps, though less charismatic than megafauna, form an essential part of ecosystems around the world yet are the most endangered of the three taxa examined in the data collection. What makes this even more worrying is that the space and resources needed for say, an amphibian tank, are about a thousandth of the scale of the resources required for an ungulate or big cat exhibit.

In conclusion, zoos should incorporate more endangered reptiles and amphibians (especially the latter class, which has been in a nosedive in terms of numbers in the past few decades) and continue to evolve their collections to contribute further to ex situ conservation. While perhaps it may be better that zoos generate as much money as possible for in situ conservation, there are species out there which are in dire need of a captive fall-back.