In recent days, as we've shown you, Ukrainians hiding in shelters are leaving their homes during the Russian military invasion of their country.

You might have noticed they included the elderly as well as women and children.

But where are the young men?

When Russia launched what it called a, quote, "special military operation" in Ukraine on February 24th, Ukrainian President Vladimir Zelensky declared martial law when a country's armed forces take control during a national emergency.

Part of that made it illegal for men between the ages of 18 and 60 to leave Ukraine.

Some of them have been drafted into the Ukrainian military, others may be in the days ahead.

And the nation's government says more than 66,000 Ukrainian men have returned there from other countries to join the fight against Russian troops.

It also says more than 20,000 foreign volunteers from 52 nations have said they joined the fight on Ukraine's behalf.

Meantime, the US defense official says Russia is trying to recruit foreign fighters as well, including people from Syria, to supplement Russian forces in Ukraine.

We don't have an estimate on how many foreign troops might be involved on the Russian side, but US officials say that countries fight in Ukraine has been harder than the Russian government expected.

Russia said at the beginning of its invasion that it would only target Ukrainian military sites, but several civilian sites, from apartment buildings to college buildings to a Ukrainian Orthodox Church, have been damaged or destroyed.

As far as casualties go, we don't know how many thousands of people have been killed in the conflict⏤the Russian and Ukrainian governments give vastly different counts when it comes to their soldiers' deaths.

But the United Nations says it believes more than 400 civilians have lost their lives.

The UN also says more than 1.7 million Ukrainians have left their homes.

Many are crossing their country's border into Moldova, a much smaller nation south of Ukraine.

There's a family that has just crossed the border from Ukraine into Moldova; they came from the town of Mykolaiv, [a] scene of some pretty intense fighting.

And they are some of the hundreds of people that we've seen crossing this border in just the last couple of hours in the cold, in the snow flurries.

People with very little children in strollers are now suddenly refugees.

The amount of humanity that has crossed the borders from Ukraine into Moldova in just the last week and a half: more than 230,000 people.

I spoke with Moldova's prime minister, who predicts this situation will get much, much worse.

So, every eighth child in Moldova is now a refugee.

So, about three-fourths of the refugees are actually staying with families.

A lot of Ukrainians have friends or relatives in Moldova, but also regular people have just taken in Ukrainian families into, and invited them into their homes.

Complete strangers? Yes, absolutely.

Do you think the refugee exodus will get worse in the days and weeks ahead?

I'm afraid so.

The Moldovan government is providing free transports for people from the border; they have opened their doors to these Ukrainian refugees.

But Moldova is a small country and clearly needs help with this.

I spoke with one grandmother, who was holding her four-month-old granddaughter, who said her home had been destroyed by Russian troops in the town of Mykolaiv.

And she blamed Russia for this uprooting of humanity, for the uncertainty and fear and trauma that her family has been put through.

Uh...she used the Russian government's words against them.

She said, "Moscow says it has come to liberate us."

"Look at how we're being liberated from our homeland."

Ivan Watson, CNN, on the Ukraine-Moldova border.

10-second trivia: What is the most common tiger subspecies in the wild?

Bengal, Siberian, Sumatran, or Indochinese.

The most common subspecies of tiger is the Bengal, though it's still considered endangered.

While conservationists believe a few thousand Bengal tigers are left in the wild and that their numbers may be increasing, researchers think the number of wild Indochinese tigers is somewhere in the hundreds.

That's why this footage captured in Western Thailand two years ago was such a big deal.

Remote cameras filmed three young Indochinese tigers and gave hope they may be returning to the forests.

Conservationists are trying to help them along.

This lush tropical forest in northwest Thailand is hiding a rare endangered species.

It's one of the last bastions for the Indochinese tiger.

Poached to the brink of extinction for their fur and use in traditional medicine, this iconic species has all but disappeared from much of its range.

Almost everywhere, in fact, except for here.

Huai Kha Khaeng Wildlife Sanctuary is part of Thailand's Western forest complex.

With almost 7,000 square miles of protected jungle, it forms the largest intact forest block in mainland Southeast Asia, fertile ground for tigers.

And Pornkamol Jornburom is on their tail.

This is the tiger track.

So, I'm doing the measurement to make sure this is real tiger tracks.

I would say this is a healthy one adult tiger.

Jornburom works for the Wildlife Conservation Society.

The non-profit is partnered with the Thai Department of National Parks Wildlife and Plant Conservation and a project training park rangers to reduce poaching here since 2005.

Together, they developed the smart patrol system, a combination of boots on the ground, camera traps, and data collection to monitor signs of wildlife and potential threats.

Armed and trained in self-defense, these park rangers are prepared for encounters with poachers.

And, unlike other protected areas in Thailand, there have been no incidents of poaching here since 2013, according to the Wildlife Conservation Society.

By using 250 camera traps across the forest, they found that tiger numbers have more than doubled here over the past 15 years to over 60.

And this watering hole deep in the forest has become a day spa for tigers.

Somewhere to rest, relax, and rendezvous until they eventually make room for some other forest residents, like the Asiatic black bear, Asian elephant, and wild boar.

Tiger is the top predator of the food chain in [the] ecosystem, so if we are successful in conserving tiger[s], that means we can protect many other endangered species.

And as Jornburom says, big cats need big food.

Large mammals like gaur, banteng, and Sambar deer are all on the menu here.

For one adult tiger, it needs at least 50 Sambar deers a year to feed them.

2022 is the lunar year of the tiger, marking a deadline set in 2010 by 13 countries to double their wild tiger populations.

So far, evidence suggests global tiger numbers are on the rise, but the range has continued to decline.

Jornburom is hopeful for Thailand's tigers.

For example, Huai Kha Khaeng right now, we are the biggest home of [the] Indochinese tiger population.

So, while tigers worldwide face an uncertain future, these tigers can relax⏤at least for now.

Whether or not you're a dog owner, Sniffspot may not sound like something you want in your backyard.

But that's the name of a website for private dog parks people can rent, and some dog owners or lovers are offering their backyards as a sort of Vrbo or Airbnb for canines.

The owner of the Scooby Dooby Shack in Las Vegas, for example, says she's made hundreds of dollars renting out her backyard and pool to dogs.

But would this rental idea work for other pets?

Doing this for fish would go "belly up".

Ferrets would try to "weasel" their way out.

Rabbits could escape with a "hop skip" and a "jump".

Guinea pigs would have to be "wheeling" guinea pigs.

Snakes would try to "squeeze" you out of every last penny.

Hamsters give good "shavings", but not much "savings", and cats tend to "litter", so probably not.

But, hey, it still makes sense for us to visit Renton, Washington, for today's shout-out.

I want to recognize our viewers at Lindbergh High School watching there.

I'm Carl Azuz for CNN.