One out of 13 elephants in Africa was killed illegally in 2012, according to the Zoological Society of London.
South Africa arrested more than 340 poachers last year -- but poachers sometimes fight back, making the work of park rangers dangerous.
At least 1,000 park rangers have been killed in the past decade, the UK government says.
Prince Charles said poachers make use of the kind of sophisticated weaponry used in warfare, hence his call to treat the fight against them like a battle.
The wildlife trade monitoring network Traffic argues that as long as demand for illegal wildlife products remains, criminals will seek to exploit it.
"Law enforcement efforts must continue to be at the front line in the battle to protect species in their range countries and in efforts to shut down markets for illegal wildlife products," said the network's director of policy, Sabri Zain.
"However, without a complementary effort to effectively address the persistent market demand that drives this trade, enforcement action alone may sometimes be futile."