During their monthly meeting in October, several directors of Napa Valley Exposition were unnerved by the rat-tat-tat of a giant eucalyptus dropping debris on the roof of the directors’ cottage.

“It almost sounded like thunder,” director Myrna Abramowicz said afterward. “It was making me very nervous.”

Maybe it’s time to trim or remove the tree rather than wait for a major limb to crush the cottage, Abramowicz said.

As threatening as this big tree appears, nothing can be done, Joe Anderson, the Expo’s CEO, told the board. The eucalyptus is home to a white snowy owl, a protected species.

The Expo tried to remove the tree years ago, but tree services and the California Department of Fish and Game all said it wasn’t possible, Anderson said.

The Expo cut down four or five big eucalyptus, but had to leave two: the one that looms ominously over the directors’ cottage on Burnell Street and another one on Burnell at Fourth Street that is the home of a red-tailed hawk, he said.

The Expo offered to find a way to relocate both raptors, but Fish and Game balked, Anderson said in an interview. “At the time, they told us it was impossible,” he said.

Anderson said he agreed with Abramowicz that a eucalyptus of such tremendous size is hazardous. “I think they’re risky because they’re eucalyptus and eucalyptus are very unpredictable,” he said.

Until a decade ago, the food court near the Plaza Stage was dotted with eucalyptus well over 100 feet tall. One by one, the Expo began removing them.

The last cluster was taken out after several large limbs crushed unoccupied food booths along Fourth Street during a storm. Insurance covered the building repairs, but only on the condition that the Expo reduce the future hazard, Anderson said.

Anderson said the white snowy owl and the red-tailed hawk have been in residence for years. As far as he can tell, they are year-round nesters.

The most recent eucalyptus removals were done by Britton Tree Services, which discovered the owl’s nesting hole.

“You find a live nest, you can’t touch it or else the feds will throw you in the pokey,” Joe Borden, Britton’s owner, said. Both the white snowy owl and the red-tailed hawk are protected by the federal Migratory Bird Act, he said.

Borden said he believed the Expo could trim around the protected nests as long as they were not disturbed. Neither tree is particularly dangerous, he said.

“Eucalyptus get a bad name, but they’re no more dangerous than any other tree. They have incredibly strong, dense wood,” he said. “People are afraid of them because they’re big.”

Corinne Gray, an environmental scientist at Fish and Game, said nests of raptors are protected, particularly when young are being raised. And yes, raptors can stick with a nest for years.

But Fish and Game generally does not prohibit the removal of individual nuisance trees, Gray said. “We discourage people from doing it unnecessarily, but if it’s a safety issue it’s a safety issue.”

“We just ask that they do it at the right time,” she said.

Anderson said he would further explore whether the eucalyptus trees can be removed or trimmed. “If we can find a way to do it legally, we’d do that,” he said.