MAMMAL WATCHING -- The renovated Small Mammal House opens this Friday with a ceremony beginning at 10:30. Refreshments will be served and Theodore H. Reed, who is retiring as Zoo Director, will cut the ribbon at 11. The public is invited.

"A lot of these animals haven't seen the public in more than two years," explains collection manager Bill Xanten, apologizing for the shyness of a fennec fox, which is just getting used to its new home in the renovated Small Mammal House at the National Zoo.

The Small Mammal House, built in 1937 as a WPA project, will reopen this Friday after a 30-month, $2 million renovation during which many of the residents were off exhibit. Now the animals -- 45 species of them -- are back. Except for the exterior brick walls and tile roof, you'd hardly recognize their old home. Gone are the iron bars and small cages, replaced by glass enclosures that simulate each animal's natural habitat.

"There used to be a concrete pillar here to hold the building up," explains Xanten. "We made it into a tree."

On the branches of the "tree" rest two binturongs, giant civet cats from Southeast Asia. The small-clawed otter's quarters include a small pool and surroundings made not with real dirt but with what Xanten calls "mud mix" -- a combination of dirt, stones, sticks and concrete. The replica of the termite mound, where some dwarf mongoose are playing hide and seek in the tunnels, was created by dribbling wet cement, sand-castle style. The rock hyrax -- three of them -- can jump from ledge to ledge in their new quarters, and the spiny mouse is seen against the backdrop of a sunrise.

"It's partly for the public, but the animals benefit, too," says Xanten. "They can interact better in a setting that's like their natural environment. Their anatomical structure is based on where they live."