Animals are usually transported to different countries, he added, making it difficult to catch the bad guys.
That's why Hayward would like other countries to establish their own exotic animal theft registries or partner with his agency.
He believes a worldwide network would help increase the number of stolen animals recovered and lead to more arrests.
Harry Schram, director of the 306-member European Association of Zoos and Aquaria in Amsterdam (EAZA), said some 40 percent of zoos have been victimized.
Facilities are now beefing up security in an effort to curb break-ins.
"We're trying to contain it," he said.
But the effort comes with a high price tag. The cost of extra security takes money away from important breeding and conservation programs, he said.
In addition to installing cameras and hiring security guards, most zoos implant their animals with identification microchips. And when an animal is stolen, other EAZA facilities and the police are immediately notified.
"We try to exchange information as much as possible with other zoos and private collectors," Schram said.
"We all have an interest in making sure that not too many animals—or none at all—are being stolen."
To prevent thieves and dealers from knowing the true monetary value of animals—and hopefully quashing the temptation to steal them—European zoos don't sell them.
"Animals are usually traded just for the transportation cost from one zoo to another," Schram explained.
"They have no economic value within the EAZA zoo community."
Spate of U.S. Thefts
European zoos aren't the only ones grappling with thefts. American facilities have also had prized animals swiped.
Two female koalas were stolen from the San Francisco Zoo seven years ago.
The thieves climbed onto the zoo exhibit's roof and broke through a skylight. Acting on an anonymous tip, police later recovered the marsupials.
More recently an 8-pound (3.6-kilogram) Chinese alligator named Mr. Grumpy disappeared from the Ellen Trout Zoo in Lufkin, Texas.
Zoo officials believe the rare reptile may have been stolen.
Zoo director Gordon Henley said there were no signs of a break-in, but scaling the enclosure's six-foot (two-meter) glass wall isn't difficult. Several visitors have climbed into the exhibit to get better pictures of the reptiles.
This is not the first time something like this has happened, he added. Every ten years or so an animal is stolen, Henley said.
But he remains hopefully that the three-foot (one-meter) alligator, which has been missing since December, will be recovered.
"We've had pretty good success in the past—if [the animals have] actually been stolen—with catching the people," Henley said.
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