Two tigers traveled 200 kilometers to reunite and give birth to a cub. Why did scientists forcibly separate this pair of childhood sweethearts?

Boris is a male Siberian tiger, and Svetlana is a female Siberian tiger. Although they are not related by blood, they have very similar growth experiences. Now, their fates are completely intertwined.

In the last century, Siberian tigers were the main targets of poachers. Many adult tigers died tragically under hunting guns, leaving behind helpless cubs . In 2012, researchers met Boris and Svetlana, who had just become orphans, in the Sikhote-Ottoman Mountains in the Russian Far East.

At the time, they were only 3 to 5 months old, and the researchers decided to take them back to the conservation center to participate in a newly established wild reintroduction project.

The Sikhote-Sukhot Mountains are located in the southeastern part of the Russian Far East and are an important habitat for the Siberian tiger. | Source: Wikipedia by Вадим Юшкевич

A year and a half later, Boris and Svetlana, who had completed the project, were released into the Amur River region. In order to expand the range of Siberian tigers in the region, their release points were deliberately set about 200 kilometers apart. However, in the winter of 2015, researchers discovered that the GPS locations of the two tigers overlapped dramatically:

Boris traveled thousands of miles to be with Svetlana, and the two tigers who grew up together formed a family!

Boris and Svetlana were captured on camera together in 2018 | Source: ANO WCS

Recently, an article published in the Journal of Wildlife Management detailed the details of the experiment and tracked six tigers, including Boris and Svetlana. This surprising and touching reunion proves the success of the rewilding program and brings hope for the restoration of the wild population of Siberian tigers.

In the past, Siberian tiger cubs without parents usually faced two outcomes: one was to be sent to a zoo to spend the rest of their lives there; the other was to be released back to the traditional habitat of Siberian tigers and let them face the challenges of survival alone. In the past decade or so, the wild reintroduction project has provided another possibility for the lives of these lonely little ones.

Little Boris is examined after being rescued | Source: Dale Miquelle

The project has two major features, one of which is to provide young tigers with a semi-domesticated environment without human contact.

When it is confirmed that there is no adult tiger claiming the cub, it will first be isolated for a month before entering a carefully designed enclosure with tigers of the same age. The edge of the enclosure is a 4.5-meter-high fence with a 1-meter-long top extension. The fence itself is physically shielded, and in some locations there are cages that can be opened and closed remotely for staff to put live food.

The purpose of all this is to prevent the tigers from seeing the keepers so that they don't associate food with the presence of humans.

Throughout the project, researchers mainly observed tigers through cameras | Source: Amur Tiger Center

When the tigers are under 11 months old, staff will regularly release small prey such as rabbits and pheasants that are easy to catch. When the tigers are about 1 year old, their food changes to young wild boars and young sika deer. As the tigers age, it will become increasingly difficult to catch prey until the diet is consistent with that of wild tigers.

Before being released, each tiger must successfully kill at least 24 wild boars or sika deer and must also meet a series of assessment criteria related to hunting ability.

Reconstruction of a Siberian tiger hunting | Source: Wikipedia by Stefano Stabile

Another special feature of this project is the choice of release location .

Tigers are typically released into areas where they already exist, but a 2023 study concluded that this approach does not provide the greatest benefit in increasing wild tiger populations.

For example, historically, both sides of the Amur River were once the range of Siberian tigers, but in the middle of the last century, rampant poaching, habitat destruction and human activities caused tigers to disappear from the area. Today, the Amur River still has the hardware conditions for Siberian tigers to survive and reproduce, but due to the absence of the "big cats", these lands have been wasted .

The Amur River is the Heilongjiang River. Since the text refers to the Russian side of the river, it is called the Amur River bank | Source: Wikipedia by DNSokol

The 2023 study found that there are about 4,500 wild tigers in Asia today, but they only range in 8% of their historic range. If tigers were released into "suitable but vacant" lands, their range could expand by up to 50% .

That’s why the Russian program chose to release Boris and Svetlana along the Amur River, where tigers are rarely seen, rather than returning them to their birthplace.

However, no one can say for sure whether these tigers, which have not been raised by their parents since childhood, can shoulder the heavy burden of "expanding territory", so researchers installed various tracking devices on them before releasing them.

Another female tiger in the project named "Cinderella" formed a family with a wild tiger and gave birth to 4 cubs | Source: The Bastak Nature Reserve

So far, the results are good.

Of the six tigers in the latest article, only one had a less-than-smooth reintroduction journey. After returning to the wild, the male tiger crossed the border into China and attacked 13 sheep in a farmhouse in one night. When he returned to Russia, researchers recaptured him and placed him in a zoo, raising him in a similar manner to before.

The other five tigers did not attack humans or livestock , and their diets and hunting success rates were almost the same as those of wild tigers. Even more gratifying is that these five tigers have found each other's partners and gave birth to at least six cubs, making a huge contribution to the return of the Siberian tiger.

In addition to the article, there are 8 tigers that are not under special surveillance, and none of them have attacked humans or livestock | Source: Amur Tiger Center

It was during the process of closely tracking them that the researchers witnessed the romantic story of Boris and Svetlana. More than a decade ago, when the researchers picked up two orphans who could not survive on their own in the mountains, they certainly could not have imagined that they would one day have their own children, although they may never know the efforts made by humans behind the scenes.

What Boris and Svetlana didn't know yet was that they were also making a contribution to their own kind.

Now that researchers know that captive-bred tigers can survive successfully in the wild with minimal human involvement, they plan to apply this strategy to more cats in need.

In 2017, the camera captured Svetlana with a tiger cub hidden behind her. With the increase of protection awareness, her cubs will not be orphaned as easily as before | Source: PROO Tiger Center

The "romantic romance" in the ice and snow may reappear again.

References

[1]https://wildlife.onlinelibrary.wiley.com/doi/epdf/10.1002/jwmg.22691?saml_referrer=

[2]https://www.smithsonianmag.com/smart-news/two-orphaned-siberian-tigers-reunite-as-mates-after-one-trekked-120-miles-through-russian-wilderness-180985660/

[3]https://www.nytimes.com/2024/12/11/science/siberian-tigers-russia.html

[4] https://amur-tiger.ru/en/

Planning and production

Source: Bringing Science Home (id: steamforkids)

Author: Liu Liuqi

Editor: Wang Mengru

Proofread by Xu Lailinlin