From recent uproar over the killing of Cecil the lion in Zimbabwe to historical poaching and destruction of habitats, the biggest threat to endangered animals has come from a fellow inhabitant of the earth.
It is estimated that 99.9% of all the species that have ever lived are now extinct. The rate of those extinctions has accelerated dramatically over the last century however, and humans stand accused of being the main cause.
Early 20th Century
During the first half of the 20th Century, hunting elephants and other exotic wildlife was viewed as a more trivial issue than it is today.
Ivory and animal carcasses were commonly used to fashion ornate items of homeware and, while demand in the west may have dwindled, the trade is by no means dead. Research conducted in 2014 suggested around 35,000 African elephants a year are killed, with demand for ivory products in Asia blamed for fuelling the problem. If this rate continues, it is feared that elephants could be extinct within a century.Elephant poaching deaths reach tipping point in AfricaFight to save the world's Northern White rhinos
1966 to 1968
Man has been responsible for bringing many species to the brink of extinction, but there are other reasons why some find it difficult to thrive.
Breeding endangered animals can be incredibly problematic. Particular problems have persisted with pandas in captivity. One male Panda, An An, found this out first hand when he was rejected not once but twice by female counterpart Chi Chi in the late 1960s. Scientific breakthroughs since have seen higher numbers of pandas being born in captivity and it is hoped that within 10 years, China could reintroduce some pandas into the wild.Mating pandasTeaching an endangered zoo animal to love again
Who can resist the appeal of a panda, except another panda
The price of poaching
Northern white rhinos now stand on the point of extinction, largely due to the effects of poaching over a number of decades.
The animals are prized for their valuable horns and, even though a concerted effort has been made to offer them full protection, they remain dangerously under threat.A looming mass extinction caused by humansWhy such a fuss about extinction?
In the late 1960s, there were fears that mountain gorillas in Rwanda could soon become extinct.
In the UK, television helped the wider population to establish an affection for exotic animals, thousands of miles away. In 1979, David Attenborough visited gorillas in the volcanic forests on the border of Rwanda and Zaire. The footage captured was voted as one of the top TV moments of all time and brought the plight of endangered animals to wider public notice.David Attenborough's favourite momentsBBC Nature: How to be a wildlife volunteer
1998 to 1999
Wreaking havoc on habitats
Animals have certainly suffered at the hands of hunters, but changes in the environment have come to be understood as an equally major threat.
In the late 1990s, the effects of pollution, global warming and deforestation came in to sharper focus as more species came under threat. The International Union for Conservation of Nature estimates that at least 50 animals move closer to extinction every year as a result of human behaviour. The superb lyrebird of Australia has become so used to deforestation it has incorporated the sound into its mating ritual.Earth 'entering new extinction phase' - US studyNature loss 'to damage economies'
You can't just take an attitude that we own the global biosphere
2000 to 2003
Undead as a dodo
The film Jurassic Park was a work of science fiction, but the logic of bringing extinct species back to life is actually a distinct possibility.
Although the DNA of dinosaurs is too old and fragmented to use in such a process, attempts to bring some more recently extinct animals back to life (dubbed de-extinction) may be possible. The bucardo, a type of wild Spanish goat, became extinct in 2000. Three years later, scientists were able to clone a calf which died a few minutes after birth. There have even been suggestions that by editing the genome of an Asian elephant, a variant of a mammoth could be created.Is 'de-extinction' possible?Fresh effort to clone extinct animal
Cecil the lion
In July 2015 outrage spread across the world wide web after a famous lion, Cecil, was killed on a hunt in Zimbabwe.
American dentist Walter James Palmer reportedly paid $50,000 (£32,000) to shoot Cecil the lion with a crossbow. Owing to his status as a major tourist attraction and the subject of research by Oxford University, Cecil was supposed to be particularly protected. Those who killed Cecil say they were not aware of this. The public reaction was such that big game hunting and, more generally, man’s relationship with animals has once again become the subject of intense debate.Cecil the lion: Why a hunting ban is not the answerWhen is it hunting and when is it poaching?