Pandas are a vulnerable species. American zoos are allowed to fly them in from China and display them to tourists on one condition: They have to prove to federal regulators that they are helping pandas in the wild.

For the most part, they do this by paying fees to two Chinese government organizations, which are supposed to spend the money on panda conservation.

My colleagues and I spent months researching this arrangement. We collected around 10,000 pages of records, including financial reports that zoos provided to the U.S. Fish and Wildlife Service on about $86 million that was sent to China.

What stood out was how often zoos had no idea where the money was going. When records did exist, a portion of money went toward patrol vehicles and other items needed to protect land. But we found many instances in which American zoos signed off on projects to pay for the likes of apartment buildings, computers and museums in China, or agreed to cover costs at Chinese zoos.

This has persisted for decades, but American zoos haven’t disclosed it publicly. Regulators at the Fish and Wildlife Service quietly froze payments to China at least three times, citing incomplete record-keeping.