Trends in European zoo collections in the 21st century

From pieces of news which I gathered, white rhinos started breeding when it was discovered that females are susceptible to chemicals called phytosterols found in some fodder plants like alfalfa. They shut down the young females' reproductive system. When it was corrected, and with a new batch of females, breeding became successful.

This shows something often overlooked. The skill of breeding in zoos needs to be cracked only once and is often a single difficult thing. Afterwards, animals like rhinos can breed potentially for infinity. In contrast, conservation in the wild needs to be successful every single day and year - keep out poachers, maintain political stability, etc. That is why conservation of rhinos and some other animals in zoos is much more optimistic and in the wild much more pessimistic than the current state suggests.
 
From pieces of news which I gathered, white rhinos started breeding when it was discovered that females are susceptible to chemicals called phytosterols found in some fodder plants like alfalfa. They shut down the young females' reproductive system. When it was corrected, and with a new batch of females, breeding became successful.

This shows something often overlooked. The skill of breeding in zoos needs to be cracked only once and is often a single difficult thing. Afterwards, animals like rhinos can breed potentially for infinity. In contrast, conservation in the wild needs to be successful every single day and year - keep out poachers, maintain political stability, etc. That is why conservation of rhinos and some other animals in zoos is much more optimistic and in the wild much more pessimistic than the current state suggests.

Another big step forward was the realization that daughters won't breed in the same herd as their mothers, as they are being hormonally surpressed by the mother. So unlike elephants young females have to be moved out of their maternal herd quite early.

I think I understand why the common perception is that zoos become less and less diverse, but the total number of species slightly increases. it is because new zoos spring to existence or build exhibits, which compensates for erosion of old city zoos.

That is indeed part of the puzzle, but does not explain it all. I don't want to go into too much detail yet as this will be part of the final mammal posts once all the families have been covered.
 
Number of zoos kept (current and former during the holding period):
A 1 zoo
B 2-5 zoos
C 6-10 zoos
D >10 zoos

Time period kept:
1 < 1 year
2 1-5 years
3 6-10 years
4 11-20 years
5 > 20 years

* Species successfully bred
♱ Dead end (in case of species gained)
↑ Species gaining popularity (in case of species gained)

Horses - Equidae
# Species kept 1-1-2000: 7
# Species kept currently: 7
# Species gained: -
# Species lost: -


The domestic horses and donkeys are some of the first animals a kid recognizes and zebras follow quickly after. It is however the less known species that hold the greatest interest to zoo nerds and there are a few of those, though they aren’t all doing equally well. Breeding has never really been the problem, but finding zoos that are interested is a challenge if you are a wild ass. Which means more than one critically endangered ass ended up as a lion's dinner. Plains zebra (Equus quagga) are by far the most widely kept species of wild horse, though the number of zoos with pure subspecies herds is lower than zoos or Zootierliste let you believe. In recent years the maneless zebra (ssp borensis) has seen a small spread, but this near-maneless zebra hasn’t really caught on. Until recently all 7 species could be seen in Tierpark Berlin, though with the departure of their Chapman's zebra one now has to visit that other Berlin institution for a full equid card.

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@4ways NAP Maneless zebra have a very small wild range, but in zoos haven't caught on yet either

Species gaining popularity

African wild ass - Equus africanus
Somali wild ass (ssp somaliensis) are probably the only extant subspecies of the ancestors of the domestic donkey. But Somali wild asses are also extremely rare in the wild. Interest in this species has however grown this century with the number of holders nearly doubling this century. That is good news for a beautifully unflashy animal, though without its critically endangered status it would probably suffer from a lack of interest.

Mountain zebra - Equus zebra
Hartmann’s mountain zebra (ssp hartmannae) are another African equid that has seen a clear increase in popularity, with a doubling in the number of holders. An increasing number of zoos is looking towards a more endangered alternative of plains zebra and Hartmann’s mountain zebra can be that answer, even though they are not always the easiest species in a mixed savanna enclosure. Plenty of zoos do keep them in a mixed species exhibit, though the list of failures is long too.

Grevy’s zebra - Equus grevyi
In a bit of a similar story as Hartmann’s mountain zebra, zoos that are looking for a more endangered replacement of plains zebra do also end up with Grevy’s zebra. This species has long been the second most common zebra species in Europe and still is that, despite gaining some ground. They are often kept in mixed species habitats but can be quite aggressive in those, so it is not always a happy story.

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@Tim May Somali wild ass are stunning animals, despite their bland coat pattern.

Species losing popularity

Kiang - Equus kiang
Whereas African equids have success in finding new houses, the kiang has become Europe’s rarest wild horse. It isn’t endangered, which doesn’t help these days, but that so few zoos have an interest in the beautiful animals is still surprising. Zoos interested in Asiatic wild asses probably first opt for the endangered onager (Equus hemionus onager) or kulan (E.h. kulan), though neither subspecies has really seen their popularity increase and their numbers have slightly decreased too. Of the current kiang holders, multiple only have a few animals and the number of breeding institutions is quite low, which means we could see a bigger decline in the near future.

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@Bwassa Kiang are an Asian highland species that doesn't profit from extra interest

Only one order left, but certainly not the least!

Progress
21/22 orders completed
93/106 families completed
509-518 species present in 2000
526-529 species present in 2023
220-229 species gained this century
210-214 species lost this century
 
Species losing popularity

Kiang - Equus kiang
Whereas African equids have success in finding new houses, the kiang has become Europe’s rarest wild horse. It isn’t endangered, which doesn’t help these days, but that so few zoos have an interest in the beautiful animals is still surprising. Zoos interested in Asiatic wild asses probably first opt for the endangered onager (Equus hemionus onager) or kulan (E.h. kulan), though neither subspecies has really seen their popularity increase and their numbers have slightly decreased too. Of the current kiang holders, multiple only have a few animals and the number of breeding institutions is quite low, which means we could see a bigger decline in the near future.

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@Bwassa Kiang are an Asian highland species that doesn't profit from extra interest
First off, I want to say that this has been a truly fascinating thread to follow, @lintworm! I greatly appreciate all of the time and effort that has gone into presenting this. I am very excited that you have now reached the ungulates, which are my area of expertise from an American perspective. I am looking forward to seeing how our two regions compare in these groups that I am most familiar with.

Now to speak specifically on the kiang -- I have heard from colleagues that worked with kiang while they were still present in the United States that they are the most difficult Equid species to work with. They said that they are particularly high strung, erratic and unpredictable, and extremely aggressive to both other animals and people. They said of all the Equids, the kiang have surely earned the name "wild ass" :P I wonder if it is this demeanor that has also lead to their decline on the other side of the pond, as well?
 
Mountain zebra - Equus zebra
Hartmann’s mountain zebra (ssp hartmannae) are another African equid that has seen a clear increase in popularity, with a doubling in the number of holders. An increasing number of zoos is looking towards a more endangered alternative of plains zebra and Hartmann’s mountain zebra can be that answer, even though they are not always the easiest species in a mixed savanna enclosure. Plenty of zoos do keep them in a mixed species exhibit, though the list of failures is long too.
I was under the impression the AZA Ungulate TAG recommended mountain zebra for mixed species enclosures, in place of plains zebra as you mentioned. Just how different is the behavior of these two species? Perhaps @Kudu21 can provide some insight?
 
Now to speak specifically on the kiang -- I have heard from colleagues that worked with kiang while they were still present in the United States that they are the most difficult Equid species to work with. They said that they are particularly high strung, erratic and unpredictable, and extremely aggressive to both other animals and people. They said of all the Equids, the kiang have surely earned the name "wild ass" :p I wonder if it is this demeanor that has also lead to their decline on the other side of the pond, as well?
You beat me to it - I've heard the same thing from European kiang keeping institutions. Stallions in particular seem to be real "sweethearts". Might also explain why they were never domesticated.
 
I was under the impression the AZA Ungulate TAG recommended mountain zebra for mixed species enclosures, in place of plains zebra as you mentioned. Just how different is the behavior of these two species? Perhaps @Kudu21 can provide some insight?
The AZA Equid TAG recommends mountain zebras in place of plains zebras in mixed-species exhibits because they know zoos want zebras in their mixed-species exhibits -- not necessarily because they work well in mixed-species exhibits. They just happen to work better than Grevy's zebras and are more conservation dependent than plains zebras. Conflict between Equids and other animals in mixed-species exhibits is pretty much unavoidable, but it can be manageable, depending on the setup, the individuals, and how much risk/conflict a facility is willing to accept.
 
The upcoming post will be one of the most exiting in the entire thread. I'm really curious if Zoochats expectation for the even toed ungulates come true. Personally, i would also say that there is a decline in the total amount of ungulates kept by zoos (Without any proof). But as there are some species quite new to Europe (mainly because of the former Berliner director), i slightly doubt that the lose is as high as expected at the first sight.
 
The ungulates have certainly been what I have been looking forward to the most, I'm particularly interested in seeing where the caprines end up.
 
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African wild ass - Equus africanus
Somali wild ass (ssp somaliensis) are probably the only extant subspecies of the ancestors of the domestic donkey. But Somali wild asses are also extremely rare in the wild.

It is a bit contentious, but I thought the Nubian wild ass was the ancestor of the domestic donkey
 
First off, I want to say that this has been a truly fascinating thread to follow, @lintworm! I greatly appreciate all of the time and effort that has gone into presenting this. I am very excited that you have now reached the ungulates, which are my area of expertise from an American perspective. I am looking forward to seeing how our two regions compare in these groups that I am most familiar with.

Now to speak specifically on the kiang -- I have heard from colleagues that worked with kiang while they were still present in the United States that they are the most difficult Equid species to work with. They said that they are particularly high strung, erratic and unpredictable, and extremely aggressive to both other animals and people. They said of all the Equids, the kiang have surely earned the name "wild ass" :p I wonder if it is this demeanor that has also lead to their decline on the other side of the pond, as well?

Glad you (and others) appreciate the thread. This is the first thread where I really doubted if I hadn't bitten of more than I could chew. As all the work is manual it is easy to miss stuff and I don't always have enough expertise to make the right calls when analyzing trends. So lots of room for potential errors. And it just is a lot of work if you want to do the animals justice (the mammal document is over 140 pages, excluding pictures and the progress stats per post). You Zoochatters should be very glad that one of my main strengths is underestimating how much work something is :p

I am thus always happy if someone with keeper/zoo experience can add information. I use what I can find, but such insights as you give are hard to find and do add a lot of context.
 
Finally caught up with my favourite thread, and just in time for my favourite family.

Now, this may be bias, but I think it would be remiss not to mention the Takhi, even though their population was quite stable already in the 20th century. The number of holders appears to be steadily increasing, and I've often wondered if this is partially due to their history of reintroduction into the wild. In an increasingly anti-zoo climate, keeping a (sub)species which is the poster child for "saved by captivity" must be preferable to keeping something like the kiang, that has no captive history behind it and isn't particularly vulnerable.
 
Glad you (and others) appreciate the thread. This is the first thread where I really doubted if I hadn't bitten of more than I could chew. As all the work is manual it is easy to miss stuff and I don't always have enough expertise to make the right calls when analyzing trends. So lots of room for potential errors. And it just is a lot of work if you want to do the animals justice (the mammal document is over 140 pages, excluding pictures and the progress stats per post). You Zoochatters should be very glad that one of my main strengths is underestimating how much work something is :p

I am thus always happy if someone with keeper/zoo experience can add information. I use what I can find, but such insights as you give are hard to find and do add a lot of context.

This has been such an interesting thread and your others are ace so I am hoping you underestimate work on many other things!
 
Now, this may be bias, but I think it would be remiss not to mention the Takhi, even though their population was quite stable already in the 20th century. The number of holders appears to be steadily increasing, and I've often wondered if this is partially due to their history of reintroduction into the wild. In an increasingly anti-zoo climate, keeping a (sub)species which is the poster child for "saved by captivity" must be preferable to keeping something like the kiang, that has no captive history behind it and isn't particularly vulnerable.

Looking at Zootierliste data the number of holders seems to have been extremely stable for such a widespread species with about 10-15 zoos gaining and 10-15 zoos going out of the species since 2000. Maybe they have made some gains in your area, but overall I didn't see any evidence of such a shift.
 
EVEN-TOED UNGULATES & WHALES - ARTIODACTYLA

This order is a somewhat unexpected marriage between ungulates and whales and until the early 1990s it wasn’t known that whales are in fact ungulates that have forgotten how to walk and be vegetarian. Because the stories of cetaceans and ungulates are 2 different ones I will treat them as separate groups here, even though that isn’t scientifically correct.

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@Sicarius Pygmy killer whales are in fact some hyperspecialized hippos lost at sea

EVEN-TOED UNGULATES - ARTIODACTYLA (EXCLUDING CETACEA)
250 species across 10 families
124 species kept this century (50%)


With the exception of the pronghorn (Antilocapridae) all ungulate families are currently represented in European zoos and of them the bovids are one of the most well-represented mammal families in European zoos in terms of species present.

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@Arizona Docent Pronghorns have been absent from Europe for 50 years now, though masterplans tend to still include them from time to time

Camels - Camelidae
# Species kept 1-1-2000: 2
# Species kept currently: 2
# Species gained: -
# Species lost: -


The majority of the species in this family are domestic species, and of the 3 wild species only the 2 South American ones are represented in Europe. Both are (quite) common, though the guanaco (Lama guanicoe) is strangely rare in the UK.

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@baboon Although listed in Zoo Prague's future plans, wild camels (Camelus ferus) will likely remain limited to China & Mongolia

Species gaining popularity

Vicuna - Lama vicugna
It is a bit of a repeating story, but if you are the sole member of a well-represented family/genus that is being managed as part of an EEP, that will almost automatically make you popular. In a day of spreadsheet collection planning it is an easy +. As such it is no surprise this species has been steadily gaining new holders over the past decades. In the 1970s the wild population was down to 6.000 individuals and as such it was a logical choice as one of the first EEPs in the 1980s. Since then the wild population has recovered to 350.000 mature individuals according to the IUCN. They are so common in Europe nowadays (79 holders) it is strange to realise what a huge rarity they are in North America.

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@ZSH While Vicuna are common, they most often don't come with a mountain view like in the Highland Wildlife Park

Progress
21/22 orders completed
94/106 families completed
511-520 species present in 2000
528-531 species present in 2023
220-229 species gained this century
210-214 species lost this century
 
Horses - Equidae

Przewalski horses in Europe spread also outside zoos to stockades, grazing reserves, semi-reserves, real reserves and released groups. Even if they are probably formally owned to zoos. I could never find a full list of such places and the level of management / wildness inside them. Some of these places keep only stallions, others not.

Which is good for several goals - saving the species, relieving zoos of surplus animals and restoring habitats and maintaining other wild species dependent on open grazed grasslands in Europe. Some released groups in Spain are even touted as a natural wildfire protection, preventing build-up of dead grass and shrub.
 
Peccaries - Tayassuidae
# Species kept 1-1-2000: 2
# Species kept currently: 3 (+1)
# Species gained: 1
# Species lost: -


These are pig-like animals that are not exactly pigs, but the New World answer to pigs. While not as ubiquitous as the Old World pigs they are fairly well represented in Europe and in 2012 the continent finally had a full set.

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@Therabu Vulnerable, but not (yet) in a breeding program White-lipped peccary are once again Europe's rarest peccary

Species gained

Chacoan peccary - Parachoerus wagneri D4*↑
Apart from a brief appearance in 1977-1978 in Zoo Berlin this species was never held in Europe. US zoos were already managing a fairly successful breeding program when Tierpark Berlin imported 2.5 animals from there. That was the start of a successful breeding program, with nearly 30 animals in Tierpark Berlin alone. From there the species spread to 11 other zoos. It is now the peccary of choice as it is the only one managed in a breeding program and it is more endangered than its smaller lookalike.

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@Therabu Chacoan peccary were one of the shock discoveries of the 20th century and have quickly gained ground in Europe

Species losing popularity

Collared peccary - Dicotyles tajacu
You are at a disadvantage if your larger cousin comes to town with the credentials of being listed as Vulnerable and managed as a breeding program. Once a common appearance in major zoos, this species is slowly disappearing from EAZA zoos and is predominantly maintained at smaller places (some of which are part of EAZA). It is still by far the most common peccary in Europe, but the trajectory is downwards (and the TAG recommends a phase-out) as opposed to increasing for Chacoan peccary and stable for white-lipped peccary (Tayassu pecari), the latter being monitored as a potential EEP candidate.

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@Goura Despite their ability to breed like rabbits the trend for collared peccary is downwards

Progress
21/22 orders completed
95/106 families completed
513-522 species present in 2000
531-534 species present in 2023
221-230 species gained this century
210-214 species lost this century
 
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Pigs - Suidae
# Species kept 1-1-2000: 6
# Species kept currently: 6
# Species gained: 1
# Species lost: 1


These are peccary-like animals that are not exactly peccaries, but the Old World answer to peccaries. The most commonly kept species, the wild boar (Sus scrofa), is also known as a lion in the vicinity of Berlin, and is one of the most widely kept mammals of them all. The colourful or endangered species of this family are gaining some popularity and are pretty widespread too.

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@Daniel Sörensen Wild boars are especially common in all the wildparks across Europe


Species gained

Visayan warty pig - Sus cebifrons D4*↑
4.4 animals, of the subspecies negrinus, were imported for Diergaarde Blijdorp, Rotterdam, in 2004. But these set foot in Europe in the quarantine in Poznan Nowe Zoo, which thus became the first holder of the critically endangered species in Europe and also the first breeder. This import has been a tremendous success and apart from another Philippine endemic, the northern giant Luzon cloud rat, there is no species that is kept since this century that has gained so many new holders. The species breeds easily, is critically endangered, fun to watch and easy to mix. So it might be no surprise that these pigs have started appearing across the continent.

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@Therabu The Elvis Presley pigs have conquered Europe

Species lost

Javan warty pig - Sus verrucosus A4
The only suid to be lost this century (yet) is one that has never been on-show. San Diego Zoo planned to import this species and 2.2 animals left Surabaya Zoo, Indonesia, for quarantine in Poznan Nowe Zoo in 1993, but that ended up being their final destination. The final animal passed away in 2004.

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@Giant Eland Javan warty pigs have found their Hotel California in Poland

Species gaining popularity

Red river hog - Potamochoerus porcus
These colourful hogs don’t mind a bit of incest and that certainly hasn’t stopped their spread. Most (if not all) of Europe’s population is at least partly descended from a few animals kept in Zoo Duisburg in the 1970s. This easy to breed species is a popular addition to any African zone and that doesn’t need to be a rainforest zone either. They can be mixed with anything from mongoose to rhinos, so are easy to fit in and enliven an enclosure, as long as you don't mind a lack of living plants.

Warthog - Phacochoerus africanus
In the shadows of the much more colourful red river hog, warthogs have also seen a (more modest) increase in the number of holders since 2000. Much of that increase can be attributed to the import of a dozen warthog from Gambia to Zoo Antwerpen, Diergaarde Blijdorp, Burgers' Zoo and Safaripark Beekse Bergen in 1996. These institutions had some great breeding success over the years with these wild-caught animals that would otherwise have been killed because of damage done to crops. Warthog had already been present in Europe for decades, but have only really taken of in the past 25 years. Some animals were originally imported as desert warthogs (Phacochoerus aethiopicus) by Moscow Zoo in 1998 and spread to Zoo Tallinn, but this is a misidentification. This subspecies (massaicus) was however lost subsequently.

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@Rhino00 It is no wonder that red river hogs are known as paintbrush-eared pigs in German & Dutch

Species losing popularity

Sulawesi babirusa - Babyrousa celebensis
This might seem a strange addition to this category since the number of animals and holders has surged again in the past decade or so. But that masks that at the start of the century this species was considerably more widespread. But in the first decade this species lost terrain very quickly, probably partly due to the rise of the Visayan warty pig. Dedicated breeding efforts in a few zoos, firmly led by Chester Zoo, have meant that this species is once again on the rise, after having been at the brink of extinction in Europe.

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@StellarChaser The exact function of babirusa tusks is unknown, the best explanation until now is that they serve as protection when fighting

Dead ends

Bearded pig - Sus barbatus
This has always been a rare species with the original stock being imported by Zoo Berlin from Singapore in 1994. The species bred there and in London Zoo too this century, but the population has slowly died out, with a single animal (*2008) remaining in Zoo Berlin. That the animals in Europe aren’t pure bearded pigs, but also have some domestic pig blood, might have been one of the main reasons for the decline, apart from a general disinterest in this large pig.

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@twilighter Berlin's final bearded pig having a bad hair day

Progress
21/22 orders completed
96/106 families completed
519-528 species present in 2000
537-540 species present in 2023
222-231 species gained this century
211-215 species lost this century
 
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