A US hunter who paid $350,000 to kill a black rhinoceros in Namibia successfully shot the animal on Monday, saying that his actions would help protect the critically-endangered species.

Corey Knowlton, from Texas, downed the rhino with a high-powered rifle after a three-day hunt through the bush with government officials on hand to ensure he killed the correct animal.

Knowlton, 36, won the right to shoot the rhino at an auction in Dallas in early 2014 -- attracting fierce criticism from many conservationists and even some death threats.

He took a CNN camera crew on the hunt to try to show why he believed the killing was justified.

"The whole world knows about this hunt and I think it's extremely important that people know it's going down the right way, in the most scientific way that it can possibly happen," Knowlton told the TV channel in footage released Wednesday.

"I think people have a problem just with the fact that I like to hunt... I want to see the black rhino as abundant as it can be. I believe in the survival of the species."

Since 2012, Namibia has sold five licences each year to kill individual rhinos, saying the money is essential to fund conservation projects and anti-poaching protection.

The only rhinos selected for the hunts are old ones that no longer breed and that pose a threat to younger rhinos.

The International Union for Conservation of Nature (IUCN) says there were about 850,000 black rhinos alive through much of the last century before hunting left only about 2,400 in 1995, but numbers have since edged up to about 5,000.

"These are incredibly majestic creatures, and their worth alive is far greater than (when) they are dead," said Azzedine Downes, of the International Fund for Animal Welfare (IFAW), one of the conservation groups opposed to the hunt.

Both black rhinos and the more common white rhino have recently suffered from soaring poaching in South Africa's Kruger Park where hundreds are killed each year for their horns which are used in traditional Asian medicine.

The exact location of Knowlton's hunt was kept secret to avoid tipping off poachers.

Television footage showed Knowlton accompanied by a professional hunter and local trackers as they tried to find a rhino that was approved for killing.

His first shots injured the animal before he fired the fatal bullets.

"I felt like from day one it was something benefiting the black rhino," Knowlton said just after the hunt ended, his voice croaking with emotion.

"Being on this hunt, with the amount of criticism it brought and the amount of praise it brought from both sides, I don't think it could have brought more awareness to the black rhino."

EU urged to do 'much more' to protect wildlife
Brussels (AFP) May 20, 2015 - European Union nations must step up efforts to protect vulnerable wildlife and habitats from the effects of human activity, with little improvement in conservation since 2007, a report said Wednesday.

The "State of Nature in the EU" report says nearly a third of wild bird species are at least partially under threat while nearly two thirds of other protected species are in an unfavourable state.

"Targeted conservation actions have brought successes, but a much greater effort is required for the situation to improve significantly," the European Commission said in a statement accompanying the report.

Despite a few successful conservation programmes, the overall state of species and habitats across the 28-nation EU "has not changed significantly" in the 2007-2012 period of the report, with many of them deteriorating still further.

Few show any chance of meeting EU targets for 2020, it said.

Conservation group WWF said the report showed that "European nature is in a dire state" and urged the bloc to do more.

Wild birds were the best off with 52 percent of the 240 species examined judged as having a secure status. But 17 percent were deemed "threatened" and 15 percent "near threatened, declining or depleted", including once common farmland birds such as the skylark and black tailed godwit.

For 1,200 other protected species -- fish, amphibians and plants -- 23 percent were secure but 60 percent were in unfavourable condition, with those living in grasslands, wetlands and dune habitats especially worrying.

Habitats were in an even worse state with just 16 percent said to be favourable, 47 percent inadequate and 30 percent bad.

The main threats were agricultural practices including overgrazing and the use of fertiliser and pesticides, plus human-related environmental damage.

EU Environment Commissioner Karmenu Vella said that despite some conservation successes, the report, which is carried out every six years, "underlines the scale of the challenges that remain."

"We have to rise to those challenges, as the health of our nature is linked to the health of Europe's people, and to our economy," he added.

WWF European policy office director Tony Long said despite the gloomy overall picture the report showed examples of how conservation can work.

"Europe has an enormous treasure in its hands that needs to be defended against increasing threats by intensive agriculture, and unsustainable energy and transport developments. There are good ways to work with nature, and they always pay off," he said.