IT'S A REAL ZOO at the White House this Christmas. At the special invitation of Nancy Reagan, bunnies, lions, reindeer and owls have made their homes on the presidential Christmas tree, which is on public view through December 29. What makes the animals unique is that they're all handcrafted decorations made of pine cones, acorns, thistles, milk- weed pods, weeds and seeds.

Ten years ago, volunteers at the Brandywine River Museum at Chadds Ford, Pennsylvania, decorated the museum's Christmas tree with ornaments in the shape of miniature animals, dubbed creatures and critters. Museum visitors fell in love with them, and every year since, the menagerie has multiplied.

Their fame spread so widely that Ted Graber, a California interior designer who decorated the Reagans' private living quarters, urged Mrs. Reagan to consider them for this year's White House tree. And she was so taken with sample ornaments that she chose them over ten other decorating ideas, according to one of her spokesmen.

In the rolling hills of Pennsylvania, 60 volunteers at the Brandywine River Museum gatherered every Monday and Thursday for the last six months making the 3,000 ornaments that adorn the tree. Led by Libby Dean and Anne Scarlett, who made the first animal decorations, they glued pine-cone petals to thistle bodies to make ears and feet, along with countless pussywillow petals used for tails and paws.

Residents at Second Genesis, a drug rehabilitation and treatment group in Virginia and Maryland, also made ornaments, following instructions from the museum.

Then museum volunteers delivered the ornaments and helped decorate the White House tree. Down came the Blue Room chandelier to accommodate the 20-foot high, 12-foot wide blue spruce. Meanwhile, 20 florists, chosen from throughout the country, on hand to decorate other White House rooms on the public tour.

Creatures and critters decorations are easy to make, by the way. With a little time, a little effort and a little glue and patience, you and your kids can create your own bunnies, lions, whales and even angels and stars, just like the ones on the White House tree. WHEN TO SEE THE TREE -- The White House is open to view the Christmas decorations Tuesday through Saturday from 10 to noon through December 29. There are also candlelight tours on December 26, 27 and 28, from 6 to 8. All tours are free. Use the Visitor Gate at East Executive Boulevard. CREATING CHRISTMAS CREATURES Here are the materials -- and a few helpful hints -- you'll need if you want to make the decorations:

* Pine cones, thistles, milkweed pods, acorns, pussywillows, black-eyed peas, black beans, evergreens, holly, berries. What you can't find by the roadside or in the woods, look for in your local supermarket or florist. Some Giant supermarkets have pussywillows for sale and many florists sell dried thistles.

* Scissors or wire cutter.

* Elmer's or Sobo glue or a glue gun.

* Thin wire to hang ornaments (floral wire is ideal).

* Clothes pins, straight pins and rubber bands are sometimes helpful for holding while glue dries.

* Parents should cut thistles and pine cones for young children.

* Cover your working area with newspaper to make for easy cleanup.

* When working with thistles, handle gently. Sometimes the spikes or curling bracts on thistle can hurt fingers.

And here's how to make them: ANGEL -- Use a pine cone for the body; glue on two halves of a split milk-weed pod for wings and an acorn for the head and a bit of cotton for the halo. BUNNY -- Use one large thistle for a bunny's body; another small thistle, cut in half, forms its head; ears and feet are petals from a pine cone; black beans or blackeyed peas are eyes and nose; and fluffy pussywillow petals are the tail and paws. Whiskers are the stem from any dried weed. REINDEER -- Use a big thistle for the body (held horizontally); glue on half a small thistle for the head; glue tiny twigs for antlers onto head; glue on pussywillow petal for tail; glue on four legs cut from stems of thistle; put wire around body of reindeer for hanger. LION -- Cut stem off thistle; leave base of thistle on (this resembles a lion's mane); cut one of the spikes off the mane to make tail and glue on; glue on four legs made from stem; glue on black bean eyes; glue on ears made with small pine cone petals; put wire around body of lion. OWL -- Take a large thistle and cut stem base off so the owl can sit up vertically; cut another thistle into half-inch slices and glue two half-inch pieces near top of large thistle for the owl's eyes, or use the backs of two acorns; glue a black bean in the middle of each eye; glue another black bean for the nose and two pine-cone petals for feet; twist wire between head and body. DUCK -- Same as bunny, but no long ears. Instead, use two pine-cone petals to form duck's bill. Use beans or seeds for eyes. WHALE -- Glue two sides of a split milk-weed pod together near the middle so that the bigger side is open and resembles the mouth of a whale; use blackeyed beans for eyes; punch hole for wire through top and bottom of whale; twist wire on underside of whale so that it won't move out of hole. FLOWERS -- The center of the flower can be a pine cone or gum ball; glue five acorns to the pine cone; let dry; add small evergreen branch or holly between acorns. STAR -- Glue milk-weed pods to a center, such as an acorn thistle or gum ball; add bright berries for color.