The scene beneath the rotor blades would have been chilling: panicked mothers shielding their young, hair-raising screeches and a mad scramble through the blood-stained bush as bullets rained down from the sky.

When the shooting was over, 22 elephants lay dead, one of the worst such killings in northeastern Democratic Republic of Congo in living memory.

"It's been a long time since we've seen something like this," said Dr Tshibasu Muamba, head of international cooperation for the Congolese state conservation agency, ICCN.

After the slaughter in Garamba National Park the killers set about removing the animals' tusks and genitals. The grim booty was likely smuggled through South Sudan or Uganda, which form part of an "Ivory Road" linking Africa to Asia.

Elephant and rhino poaching is surging, conservationists say, an illegal piece of Asia's scramble for African resources, driven by the growing purchasing power of the region's newly affluent classes.

In South Africa, nearly two rhinos a day are being killed to meet demand for the animal's horn, which is worth more than its weight in gold. More are being killed each week now than were being taken on an annual basis a decade ago.

A record number of big ivory seizures were made globally in 2011 and the trend looks set to continue in 2012 as elephant massacres take place from Congo to Cameroon, where as many as 200 of the pachyderms, listed by the International Union for Conservation of Nature as "vulnerable", were slain in January.

Conservation group TRAFFIC, which monitors the global trade in animals and plants, said 2011 was the worst year for large ivory seizures in the more than two decades it has been running a database tracking the trends.

CHINA DEMAND

After the trade in ivory was banned at the end of the 1980s -- a policy implemented to stem a slaughter of elephants at the time -- the illegal trade declined sharply, helped by the cooperation of Japan from where most of the demand had been coming.

Conservationists say there was a spike in the mid 1990s driven by emerging Chinese demand that bubbled for a few years, then dropped off as red flags were raised.

Zimbabwe-based Tom Milliken, who manages TRAFFIC's Elephant Trade Information System, said since 2004 "the trend has been escalating upwards again, dramatically so over the last three years."

The culprit, again, is demand from Asia and particularly China. Gold demand from the world's most populous country is growing at a phenomenal rate, to the point where some analysts expect China to overtake India as the biggest gold consumer this year. Demand for ivory as an ornamental item is rising in tandem.

The role of ivory and rhino horn and skin in traditional Chinese medicine is another factor. The parts, boiled and ingested, have been used for centuries in traditional Chinese medicine, which is practised not only in Chinese communities but increasingly by other ethnic groups around the world.

Elephant ivory is used to treat liver cancer and rhino horn for several types of cancers, said Wu Chi, a traditional Chinese medicine doctor in Hong Kong. He said practitioners try to use substitutes, but acknowledged demand for the real thing is very strong.

The street value of rhino horn has skyrocketed to $65,000 a kg, against $52,500 for a kg of gold at current spot prices.

"China is the undisputed key to elephant conservation today," said TRAFFIC's Milliken.

According to TRAFFIC, 161 containers of illegal, round hardwood logs and 128 ivory tusks bound for China was seized in the northern Mozambique port of Pemba last year.

Mozambican officials say 18 licences of Chinese and Mozambican companies were suspended last year for attempting to illegally export timber, ivory and rhino horn.

China's customs bureau, which oversees trade and combats smuggling into the world's second biggest economy, did not respond to requests for comment.

HIGHLY ORGANIZED

The profile of a poacher has varied over the years, from AK-wielding Somali nomads to poor rural dwellers armed with ancient muskets out to make a quick buck or put meat on the table.

As the profits have increased, however, so has the involvement of organised crime.

"The biggest challenge is that in the last few years there has been a big shift from your ordinary poachers to your organized crime groups," said Ben Janse van Rensburg, head of enforcement for the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the international treaty that governs trade in plants and animals.

"They are really, really well resourced and they have significant networks globally. You're dealing with serious trans-national organized crime," he told Reuters in a phone interview from his Swiss office.

This was on display in Congo last month, where investigators determined the poachers shot from the air because of the trajectory of the bullet wounds. Helicopters do not come cheaply and their use points to a high level of organization.

Ken Maggs, the head of the environmental crimes investigation unit for South African National Parks, said one person recently arrested for trade in rhino horn had 5.1 million rand in cash in the boot of his car.

South Africa is the epicentre of rhino poaching because it hosts virtually the entire population of white rhino - 18,800 head or 93 percent - and about 40 percent of Africa's much rarer black rhino.

As of the middle of April, 181 rhinos had been killed in South Africa in 2012, according to official government data. At this rate, more than 600 will be lost to poachers this year compared with 448 in 2011. A decade ago only a handful were being taken.

Trade in rhino horn is strictly prohibited while that for ivory is mostly illegal, although CITES allows worked ivory to be sold in Zimbabwe and Namibia. In 2008 CITES also allowed South Africa, Namibia, Botswana and Zimbabwe to hold one-off auctions of ivory stockpiles.

Despite the laws, it is not hard to find ivory in the craft markets of Kinshasa, where traders sell everything from carved wooden animals to live parrots in ramshackle stalls.

In one area of the city centre known as "the Market of Thieves", it was possible to buy both "raw" and "worked" ivory, with raw ivory costing $300 per kilo, a trader said.

"It's mainly the Chinese who buy it," the trader said, asking not to be named.

BUSH BATTLE

Many of Africa's poaching "hot-spots" have a few things in common, notably their remoteness. Big animals tend to be far from large numbers of people and the scrutiny that goes with them, giving poachers a virtual free hand.

Biannual aerial surveys conducted over the huge Niassa Reserve in northern Mozambique since 1998 point to a disturbing trend, for example.

In 2000, between 10 and 50 elephant carcasses were spotted that had been killed or died in the last 6 months. In 2009, 150 were counted and last year, 250.

"There has been a very significant increase in poaching in general and elephants in particular, especially in the last 2 to 3 years," said Anabela Rodrigues, the executive director of the company that manages the reserve.

The problem is also getting worse even in relatively developed South Africa.

Most of its rhinos are being slain in its famed Kruger National Park, which shares a porous border with Mozambique.

Under the light of a full moon, one park ranger displayed his poacher-tracking kit which included an assault rifle and backpacks with radios, night goggles and an incredibly powerful spotlight that threw a beam hundreds of meters away.

"This will burn the eyes right out of your skull," he said.

Yet despite a price tag for all of the equipment close to $30,000, Kruger is hardly winning its war with poachers.

And if South Africa is struggling, what chance do rangers with far fewer resources have in isolated corners of Africa such as Garamba, especially if they are dealing with helicopters?

"We have guards who are well trained but there's a shortage of weapons and ammunition," said Congo's Muamba.

(Additional reporting by William Mapote in Maputo, Jan Harvey in London, Jon Herskovitz in Johannesburg, John Ruwitch in Hanoi, Tan Ee Lyn in Hong Kong and Sally Huang in Beijing; Editing by Pascal Fletcher and Sonya Hepinstall)

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