The Copenhagen Zoo said Tues-day an okapi a rare African mammal related to the giraffe died from stress apparently trig-gered by opera singers rehearsing in a park 300 yards away.

The 6-year-old okapi, Katanda, collapsed Friday after Royal The-ater performers began singing se-lections from Tannhauser, said zoo spokesman Peter Haase.

She started hyperventilating, went into shock and collapsed, he said. We did all we could, but she died Saturday.

Okapis can be severely affected by unusual sounds, he said. An autopsy determined the animal suffered a severe stress attack.

Katanga was brought to the zoo last year from the San Diego Zoo. Eight months ago, she gave birth to a calf in Copenhagen.

Neither the calf nor a male okapi apeared to react severely to the singing, Haase said.

The Royal Theater deeply re-grets the animalís death, said a spokesman, Jon Stephensen. He said the concert likely will be moved away from the zoo.