The staff of the National Zoo has been unjustly criticized in another overstated Post story about animal deaths ["5 Animal Deaths Renew Criticism of Care at Zoo," front page, June 28].

The story gives little context, uses questionable sources -- including two disgruntled former employees -- and says nothing about the extensive reforms underway at the zoo. The cases, which had already been published by the zoo, are a tiny fraction of the number of animals seen by veterinarians in 2004. Also, the story does not compare mortality rates or errors at the National Zoo with those at comparable zoos.

Nonetheless, the newspaper persists in attacking the zoo's staff despite the conclusions of independent investigations by the National Academy of Sciences and the American Zoo and Aquarium Association. Their panels of experts put the National Zoo under a microscope -- and endorsed the quality of our animal care. They examined the complete picture; The Post hasn't. As the acting director of the National Zoo since January, I can say with total confidence that the National Zoo is a healthy, safe and well-run home for all of our 2,400 animals.

In assessing the level of care at the National Zoo, certain realities must be understood:

* Animal death is an inescapable part of zoo life -- the mortality rate for every living thing on this planet is 100 percent. And our staff learns from every animal death to improve future practices.

* The practice of medicine is not an exact science; 100,000 people die each year from correctly prescribed medicines. Our animal patients often have vastly different anatomies -- and none of them can talk, making zoo medicine even more difficult. Some errors are inevitable.

* We have a highly qualified staff -- of the 85 board-certified zoo veterinarians in the United States, we have three.

We work at the zoo because we love the animals, and despite media criticism, we will keep working to ensure that the National Zoo is not only a national treasure, but also a national model.

-- David L. Evans

Washington

The writer is undersecretary for science at the Smithsonian Institution and interim director of the National Zoo.