It is slaughter on a grand and stomach-churning scale.
Poachers kill more than 100 wild elephants every day to meet demand for ivory trinkets. Rhinos are dying in record numbers because their horns - long touted as an aphrodisiac - are now marketed as a cure for cancer and hangovers.
The numbers would be far worse if it wasn't for devoted men and women tasked with saving nature's finest from heavily armed human predators.
But that work has also wrought a grim toll. In the past 10 years more than 1000 park rangers have been killed, most at the hands of commercial poachers and armed militias who let nothing stand in the way of their lucrative bounty.
When Sean Willmore talks about colleagues who have been shot, buried alive or "macheted up", it's easy to understand why he thinks rangers are in a war.
So far this year the death toll stands at 56.
"I've just had the gruesome task of adding three more names to the list," he says. "They were three rangers in India who had their throats slit."
A decade ago the Australian park ranger knew little of the risks faced by his peers in the poaching hotspots of Africa and Asia.
That changed after he attended an international conference and heard rangers tell grisly stories relating to bullet holes and wounds that scarred their bodies and scalps.
Pledging to help, Willmore returned home, sold his car and remortgaged his ocean-view home to fund a documentary he made to highlight their plight.
With the A$100,000 ($109,350) proceeds, he set up The Thin Green Line Foundation, which has become the charity arm of the International Ranger Federation (IRF).
The foundation "protects nature's protectors" by providing rangers with vital training and equipment, and supporting families of the fallen. Widows and orphaned children can be left destitute and even evicted from their homes to make way for replacement ranger families.
"Dealing with the violent death of a loved one is bad enough," says Willmore. "But they also have to cope with no longer having any income, the kids not being able to go to school and being trapped in the poverty cycle.
"That not only affects the families themselves, but also the morale of other rangers who know that could happen to them. Still, I never cease to be amazed how one day they can be burying a colleague and then the next they are back out on patrol."
Up against poachers often better trained, equipped and sometimes armed to the teeth with machine guns and rocket launchers, rangers face constant danger.
"You live on adrenalin the whole time," says Willmore, who once spent two weeks with rangers in a war zone in the Democratic Republic of Congo.
"I was lucky enough to have a passport to leave. They don't have that. One ranger said to me, 'we don't know if we're going to be attacked by militia in the next hour or the next month so we are on our toes the whole time'."
Their driving force is the common denominator Willmore attributes to rangers he has met in 50 countries.
"Passion for the work, proud of what they do, proud of protecting their patch," he says.
Passionate is an apt description for Willmore, who quit his job to pursue the new vocation. Financial struggles followed, and a specialist declared that a rare tropical parasite, if left untreated, could have killed him.
In 2011 his fortunes turned when he rose from his sick bed to attend a speech by renowned primatologist Jane Goodall in Melbourne.
They chatted afterwards, and the Australian ranger's efforts resonated as a "missing link" in the fight to save endangered species and ecosystems.
Best known for her groundbreaking work with chimpanzees, Goodall has since become a "mentor and dear friend". She has helped to raise the profile of The Thin Green Line.
She also arranged for Willmore to speak at an international conference in Thailand, where one of the delegates was Claudia McMurray, an adviser to the Prince of Wales.
Impressed by his presentation, McMurray invited Willmore to St James's Palace in London to assist in developing an agenda for world leaders on wildlife crime issues.
He enjoyed face-to-face discussions with Prince Charles and Prince William.
"I treat everyone I meet with the same respect," says Willmore. "I'm not concerned with whether they are a British monarch or a ranger in the Congo.
"They came across as genuine people and I've got to say, since I met them, they have followed up on everything they said." This week Prince William marked World Ranger Day - started by Willmore in 2007 - with a YouTube message in which he lamented the "catastrophic levels" of poaching.
The Prince described rangers as the "front line" in the conservation battle and acknowledged the huge numbers killed in the line of duty.
Another big name - pop star Gotye - last night headlined a fundraising concert in Melbourne for The Thin Green Line.
It was part of an eventful week for Willmore, who is also president of the IRF.
He welcomed girlfriend Monika Colic to Australia. They met in Croatia last year and plan to live in his current home - a refurbished tram, complete with outside shower, overlooking the ocean near Melbourne.
"You have to be an optimist in this game," says Willmore of future prospects for rangers and endangered species.
"With all the information we know it would be very easy to give up. But Jane and I have discussed this, and the only thing you can do is maintain hope and do what is the right thing to do."