NIGHT STALKERS who hunt and kill African elephants for their ivory are threatening the existence of that species. And even the most drastic protective measures by conservationists are not enough. We caution you that some of the images in this Cover Story are painful to watch. M. Sanjayan of Conservation International is a CBS News Contributor:
This story was broadcast on March 9, 2014.
As a cloudless day yields to a moonlit night in this savannah in Northern Kenya, a dozen wildlife rangers armed with automatic weapons begin their nightly patrol.
Tonight, the team is on edge, says Commander John Palmieri.
"They give us a big, big worry," he said, as there is more poaching on the full moon.
And it is a deadly business. Dozens of rangers have been killed in Africa battling poachers in the last few years.
Each night, rangers go up to an observation point at higher ground, then sit all night long and scour these valleys, looking for any sign of movement, or a gunshot.
Night vision goggles help spot elephants -- and see potential human threats.
For this night at least, it was all quiet for Nature's so-called "great masterpiece."
The African elephant is the largest mammal to walk the Earth; a majestic creature that shares many noble characteristics with humans -- strong family units and maternal bonds, intelligence, longevity and, yes, terrific memories.
Also, like us, they seem to grieve, and appear to mourn their dead, a trait which, tragically, has been on display far too often of late.
Some 25,000 elephants a year are now being lost to poachers in Africa.
"It's the worst that it's been in the last 30 years," said Ian Craig. "It's a steady deterioration, and it's getting worse."
The Kenyan-born Craig leads conservation efforts for the Northern Rangelands Trust, an innovative partnership of nearly 20 wildlife conservancies.
In years past, said Craig, the typical poacher was a solitary local simply trying to feed his family. Today, though, foreign criminal syndicates with sophisticated equipment kill viciously and in ever greater numbers.
In an infamous 2012 episode, an estimated 300 elephants were gunned down in Cameroon right inside a national park.
So who's behind it?
"I think clearly China is driving this, or it's coming from the Far East," said Craig. "Ninety percent of the ivory being picked up in Nairobi Airport, or Kenya's port of entry and exit, is with Chinese nationals."
Despite laws banning the harvest and sale of ivory, it remains a powerful status symbol in China and the Far East, where it is used commonly to make artworks and religious icons.
The economic boom there has tripled the price of ivory in just the last four years. And it has rejuvenated the poaching economy in Africa.
The price on an elephant's head, Craig said, is about $2,000, or $2,500 to the gunman
"So it's several years' worth of wages from that elephant," said Sanjayan.
And therefore, said Craig, "People are prepared to risk their lives to kill them."
You hear about ivory wars, said Sanjayan, but it doesn't seem real until one comes across an elephant's carcass ... the animal had no chance against being shot by automatic weapons, no chance at all.
And then, it comes flooding right at you, and you can't escape the fact that people are willing to kill something this big just for a tooth.
There are some encouraging signs.
This past January, China crushed six tons of illegal ivory, and Hong Kong pledged to destroy 28 tons over the next two years.
Kenya has also enacted tougher anti-poaching laws. One smuggler faces seven years in jail.
But the poaching continues . . . and protecting elephants has become an arms race.
Kenya spends tens of millions of dollars a year on its 3,000-member wildlife ranger force.
Tracking dogs hunt poachers in the field and detect ivory being smuggled.
Digital radio systems now connect rangers with observation posts throughout the country. And GPS collars can track family groups of elephants in real time.
They've even built wildlife "underpasses" beneath highways, allowing elephants to travel safely through historic migration corridors.
Just as important, is getting locals invested in wildlife. In many areas, tribesmen don't just lead tours, they run the preserves.
Profits from tourism help communities understand that living elephants can be more valuable than dead ones.
"They're seeing these new lodges developing," said Ian Craig. "They're seeing better security for themselves. They're seeing money being generated from tourism going into education. And so where these benefits are clean and clear to communities, it's working."
But changing attitudes takes time -- and time is NOT on the elephant's side.
From a high of 1.3 million African elephants in the late 1970s, poaching reduced populations to critical levels by 1980.
The numbers are plummeting again: there are only about 500,000 elephants left. If poaching continues unchecked, African elephants could be functionally extinct in our lifetime.
In an extraordinary attempt to save the life of just one animal, a Kenyan veterinarian armed with a tranquilizer dart shot Mountain Bull, a 6-ton local legend who's been targeted by poachers for his massive tusks.
This magnificent bull elephant has already had lots of interaction with poachers; in one incident alone, he's been shot 8 times -- the slugs are still within his body -- but he has survived.
Now conservationists and rangers are doing something dramatic: they're taking off part of his tusks in the hopes that it will make him less of a target. The operation was over quickly, and eventually the noble giant wobbled to his feet and headed back to the bush to hopefully live out his days in peace.
But sadly is was not meant to be. Recently, the carcass of Mountain Bull was found near the foot of Mt. Kenya attacked with poison spears. The reminiscence of his tusks were unceremonious hacked off by poachers.
Craig worries that unless the lust for ivory is controlled, the elephant may not survive.
"The supply here is finite," he said. "This isn't gold. This isn't diamonds. This is even more precious, because it's been grown by an animal, and we're killing that animal to supply that demand." Video.