In the last three years, some 80 mostly small monkeys have disappeared from some of Britain's more than 350 zoos, including several dozen large zoos and safari parks, Hayward said. Only a few have been recovered.
Hayward said some animals are stolen to order by professionals. "These animals are not tame and you need to know how to handle and care for them," he said.
The more exotic or endangered the animal, the higher the price. The Royal Society for the Protection of Birds says a single rare hyacinth macaw can fetch up to $45,000.
There are casual thefts, too: In the late 1990s, a man abducted an alligator from a zoo in central England. "He took him to a party to impress his friends, then left him on the doorstep of a pet shop," Hayward said.
Harry Schram, director of the 300-member European Association of Zoos and Aquaria, says some 40 percent of European zoos have suffered thefts.
"This problem is growing. With more species being declared endangered and more regulation, people are going underground," Schram said from his office in Amsterdam, Netherlands.
Schram said police in the Netherlands and Belgium are trying to coordinate on the problem, "but this is really exceptional."
"We have no idea of the extent of thefts in Germany, Switzerland and eastern Europe and virtually no information on southern Europe," he said.
The zoo association says animals stolen in Europe likely go to European collectors, since other potential markets like the United States and Japan tightly restrict animal imports — and Middle Eastern countries are following suit.
Traffic International at Cambridge, in eastern England, which monitors trade in endangered animals across Europe, says that from 1996 to 2000, British customs officials annually seized around 450 illegally imported consignments. Around 17 percent of those were live animals, mostly reptiles, parrots and macaws.
U.S. zoos also suffer thefts. In 2000, two golden eagles and a bald eagle were stolen from Santa Barbara Zoo in California, apparently for their feathers. Also that year, teenagers stole two koalas from San Francisco Zoo.
In 2000, thieves took 16 lion cubs from a zoo in Jakarta, Indonesia. In the Middle East, four masked thieves grabbed a lion cub from a zoo in the Gaza Strip last November.
Many zoos are now increasing security and some are tagging or implanting computer ships in their animals.
Kath Bright, manager of Amazon World Zoo Park, said penguin parents Kyala and Oscar mourned the loss of 3-month-old Toga for several weeks.
"We think Toga may have been stolen to order, because this was not an opportunistic theft," she said.
There has been a happy ending: On Feb. 14, Kyala and Oscar hatched another chick, dubbed Temba, meaning hope.
