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.