On Tiger Subspecies and Captive Breeding Programs

Just something I think about every now and then. Zoos go to great lengths in the AZA (and I believe EAZA?) to keep tigers genetically pure at a subspecies level. Do the AZA and EAZA expect to release these pure subspecies? I don’t see too much other reason to keep them pure. The release of North American and European tiger populations would be an expensive and complex project. It seems like an inefficient and cost-ineffective way to conserve tigers, since I imagine working with their habitats and captive breeding in-situ will do more good with less cost. Is there any evidence to support that the captive breeding through the AZA and EAZA is a good way to conserve these animals?

I understand that zoos can serve as a back-up population for many species facing extinction in the wild, but I would imagine that large megafauna wouldn’t be the best candidates for breeding programs ex-situ due to transportation issues and the genetic drift/behavioral changes that may come with differing environments and a captive setting. I’m not suggesting that tigers be let go from zoos, but rather whether their management should be focusing on sustaining a population of tigers for educational and display purposes or Tiger subspecies for conservation and captive breeding purposes.

 

There has been talk about reintroducing tigers to Iran and Kazakhstan using the Amur tiger in place of the extinct Caspian subspecies. There have been some attempts made with the South China tigers in rewilding. Who is to say this couldn't be done with the others? Unless I'm just reading your post wrong.

 

The simplest explanation is that a hybrid/generic tiger has zero conservation value to wild populations; whereas a purebred of one of those subspecies holds a value - even if it’s only theoretical.

As @elefante has said, there have been attempts made to release tigers and discussions around doing so.

Nobody knows what the future will hold. Some of the subspecies number in the hundreds and could quickly be wiped out in a matter of years if the situation in their home range deteriorates. In that event, it’d be better to have a thriving captive population across many zoos than nothing.

 

I remember reading an article in National Geographic where George Schaller (I believe) mentioned that zoos needed a sample of the Javan subspecies in captivity. No attempt was made and of course now that subspecies is extinct.

 

I’d be really interested to read that article if you could find it. My thought comes from the fact that by treating the Tiger as multiple subspecies, you effectively end up with a larger amount of work to care for, house, and breed for separate populations. If those tigers won’t be destined for release, then it would be better to treat them as one species to free up space and resources for other species that might benefit more from captivity. In the reintroduction plans for Cambodia with WWF for example, they plan to use wild tigers, but not captive ones. I haven’t heard of any captive tigers from the captive populations in EAZA or AZA being released either. Hence, my curiosity whether the viability of these populations for release has been studied and whether this method of Tiger conservation is genuinely effective. With these populations being captive bred for a few generations (not sure how many wild tigers are implemented in the breeding program), I also wonder whether these tigers are still as fit for the wild due to genetic and behavioral changes in captivity. If there are any articles on this, I’d be really interested to read them.

 

It may be "cost ineffective" if you look at it as if it's the only way tigers in zoos are being used in conservation is their potential for being release candidates. That of course is not the case and there are numerous reasons to keep the subspecies pure that don't involve breeding for release. Your last sentence is a false dichotomy. Why can't tigers be used for both these reasons at the same time? If zoos are capable of keeping sustainable populations of the subspecies, why shouldn't they? While there isn't any plan on release right now, the choices zoos choose to make today, can affect the potential for release in the future if it becomes the primary solution to tiger extinction.

 

Fair enough, I see your point there. I can think of two other reasons to keep tigers in captivity: education and research. For research, I can understand potentially housing separate subspecies, but I'm not sure how big that demand is. For education, I don't see it as a necessity. Stand-in subspecies are used in zoos everywhere to fit the theme or for educational purposes (Amur leopards in Africa Rocks at SDZ). As for why not house separate subspecies, I imagine it would free up space and resources to consider them as one population. By choosing not to invest in separate subspecies, they can free up resources for other animals that can benefit more from zoo conservation. I can see your point though about future releases. I would be curious to hear more about whether tiger releases from captivity in zoos have been done before, to what success, and what factors contributed to their survival in the wild. I'm not a big expert on any of this stuff, so do correct me.

 

Tigers and lions will always be kept simply because of the public interest. This sustains over 1000 zoo tigers worldwide, possibly closer to 2-3,000, without controversial tiger farms in Asia. This is enough space to potentially keep all subspecies of tigers and lions separately in self-sustaining numbers. If people will demand to see tigers anyway, they can at least support education, conservation etc.

Second is the time: science knowledge and human views and values change back and forth over the years. There is no reason to think that opinions today will stay the same 10 or 25 years in future. As long as there are purebred tiger subspecies they can be mixed, but if they are mixed there will be no way back.

 

Tigers are tigers.
They all come from one ancestral stock, and they all had genetic introgression before modern population divisions, mainly anthropocentric, separated them.

 

Although the subspecies of tiger shared a common ancestor as recently as 110,000 years ago and comparatively little gene flow has occurred, studies have identified 14 genes that are subject to selection.

For example, the ADH7 gene in Sumatran tigers (the smallest subspecies) relates to body size. It’s believed to have adapted a small body size to reduce energy demands, while feeding on smaller prey such as wild pigs and small deer.

The classification of tiger subspecies are subject to frequent debate and until there’s consistent agreement, I’d prefer to see them bred and maintained as purebred subspecies. Any decision made to interbreed them would quickly become irreversible and potentially regrettable as the debate continues.

 

As for why not house separate subspecies, I imagine it would free up space and resources to consider them as one population. By choosing not to invest in separate subspecies, they can free up resources for other animals that can benefit more from zoo conservation.

They eventually could free up space for another bigcat but zoos would not stop to exhibit tigers to dedicate more space for endangered amphibians or even deers. Your reasoning about the conservation value of captive tigers apply exactly the same to lions, jaguars, leopards... Freeing up space would make sense if one specie seen as belonging from the same category would be in much dire need for captive space (for example gaur versus Javan banteng in EAZA).

We do not know where conservation may lead but already concrete attempts to release leopards after several generation in semi-wild conditions show that relasing tigers may becone an option at some point.

 

A very few examples for captive tiger releases exist for the Amur/Siberian tiger subspecies.
I post an attachment as source for a release of captive-raised Amurs from 2018.
SOURCE: Russia releases two Amur tigers into the wild

There have been reintroduction plans for Central Asia in recent years using Amur tiger as a surrogate species for Caspian (as genetics determined these populations are quite similar).

PR of China has had ambitions for reintroducing Amur tigers for years into the wild. In 1986 authorities intiatied a captive breeding program for Amur tigers at the Hengdaohezi Feline Breeding Center in Harbin, heilongjiang Province. They started with 8 Amur\Siberian tigers and by 2018 that number had multiplied to over a 1,000. individuals.
SOURCE: China to restore Siberian tiger population from captive-bred stock- China.org.cn

NOTE: The first release of a rehabilitated Amur tiger was only in 2021.
SOURCE: Siberian tiger released into the wild with collar to monitor its movements and hunting grounds - Global Times

Secondly, Sumatran tigers are frequently caught as human wildlife conflict animals and released elsewhere after capture. Non-releasable ones get transferred to Taman Safari Indonesia in Bogor.

 

Competition for space in zoos is more visible in smaller cats. Many zoos want to have 'a lion, tiger and one of spotted cats'.

Arabian, Sri Lankan and Javan subspecies of leopard are critically endangered, well distinct genetically and will need zoo breeding populations as far in future as we can imagine it, because their habitat is already transformed by people. And founder animals are available and they breed well in zoos, unlike many animals which are talked about on this forum.

I would absolutely support that some zoos holding jaguars, snow leopards, cheetah or pumas to switch to purebred critically endangered leopard subspecies. All these are more common in zoos, especially have two separate healthy populations in AZA and EAZA. Ironically, Javan leopard is now much rarer than the mysterious snow leopard.

 

I would LOVE to see a second Leopard subspecies established in US/AZA zoos, Ideally something from a warmer climate so that zoos in the Southern US can have a Leopard other than Amur (which do better in cold regions) or a Generic.

 

Southern zoos do have clouded leopards representing a more warm climate, being as both clouded and snow are not true 'leopard' subspecies.

That said, I agree, it would be great to have more subspecies of leopard. I would really love to see Arabian and Javan in holdings more.

 

Yes, I am aware plenty of Zoos keep Clouded and snow leopards. They just aren't actually Leopards. How is the Leopard situation in Europe?

 

Most zoos have Amur leopards, but there’s very few breeding recommendations being given at present due to a lack of placements for these offspring. Several young females have been sent to the USA.

There’s a small number of Sri Lankan leopard holders, with two facilities in Australasia acting as an extension to the European breeding programme.

 

So amurs are the most popular subspecies in Europe as well. It's nice that they at least have a second one though!

 

Going back as recently as the 80’s and 90’s, several European zoos held Persian leopard e.g. Bristol Zoo, Edinburgh Zoo, Aalborg Zoo and Munster Zoo; as well as a few Australasian zoos. This subspecies has slowly been phased out of both regions.

 

There is still a healthy population of Persian leopards in Europe, managed as an EEP, and which are certainly no phase-out. Same goes for North-Chinese leopards