Customs officials at Jomo Kenyatta Airport in Nairobi know to listen out for whimpers coming from crates that pass through the customs hall. As a transport hub for East Africa, animals flown illegally from one part of the world to another frequently pass through here.
Last week officials made the biggest seizure of its kind when they found five baby chimpanzees and four guenon monkeys crammed together in a tiny crate on a plane coming in from South Sudan.
"The baby chimps were found in a pitiful state and they are still emotionally traumatised by what they have been through. They probably saw their mother killed in front of them," said Richard Obanda, a senior official at Kenya Wildlife Services, which has taken charge of the animals.
"When we found them, they were starving, and some had started eating their own faeces." The chimpanzees have a black market value of around $20,000 (£10,500) each, and Kenya Wildlife Services said it believed the animals were being taken to Nigeria from Egypt. The raid highlights the magnitude of the worldwide trade in chimpanzees, mankind's closest relatives.
They are classified as a highly endangered species by the Convention on International Trade in Endangered Species (Cites) and there are believed to be only 200,000 remaining in the world. They can only be transported for very specific reasons, but 32,000 primates annually are still bought and sold on the international market. One third go to America to be kept in zoos or used in laboratory research, where they are used to research infectious diseases such as HIV/Aids and hepatitis. Conservationists estimate that at least a quarter of the trade worldwide is illegal and that as many as eight chimpanzees are killed for every one exported alive.
Interpol, the international police agency, estimates that illegal wildlife trade is worth $5bn a year, second only to drugs in the worldwide black market. Within their native habitats, chimpanzees are sought for food. Around 6,000 are killed each year and eaten by rural populations in Africa who cannot afford any other source of meat. In the jungles of eastern Cameroon and Congo, gorillas and chimpanzees have long been considered a source of food, but the dense growth that surrounded their habitats often foiled hunters. Now European logging companies have opened up huge tracts of forests and carry bushmeat from the hunters directly to the towns, where gorilla and chimpanzee meat sells at three times the price of beef.
"Chimpanzees are threatened by humans who regard then as both pets and as food," Mr Obanda said. "Many people in the Middle East like to keep baby chimpanzees as pets but once they grow to full size they get very strong and powerful. They end up frightening their owners and then end up on someone's plate. It's double jeopardy."
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