Build it, and they will come. The wetlands of the Sacramento National Wildlife Refuge are almost entirely man-made. But the millions of waterfowl that winter here aren't complaining.

Build it, and they will come. The wetlands of the Sacramento National Wildlife Refuge are almost entirely man-made. But the millions of waterfowl that winter here aren't complaining.

Now is the time to see them in their numbers. Ducks and geese take over from November through February. Shorebirds come in April on their northern migration, and songbirds can be seen in spring and summer, especially around the permanent ponds after the irrigation water dries up.

The refuge lies on the east side of Interstate 5 about three hours south of the Rogue Valley. You've probably passed it many times. Coming from the north you pass the entrance and follow the signs over the freeway and back up the access road.

Stop at a large kiosk to pay the fee of $3 (with California heading down the fiscal drain, this will likely go to $6 soon). It's well worth a stop in the visitor center to check out the stuffed bird specimens and bookstore and get the lay of the land.

There's a two-mile walking trail that begins just outside the center and a six-mile driving trail that begins at the end of the parking lot. The walking trail includes a shortcut that can cut the walk in half. On the auto route you must stay in your car except for a viewing platform and designated stretching areas. That's for the birds, literally, and it's not a onerous requirement, since your car is one of the better blinds you'll ever use.

With its variety — seasonal wetlands and marshes, uplands and grasslands, permanent ponds and riparian zones — the refuge provides habitats for many different creatures. On a recent day the walking trail wasn't very productive: the ubiquitous American coots in the ponds, yellow-rumped warblers in the trees, a few hungry turkey vultures rocking on their wings above, a lone pied-billed grebe diving for its lunch.

Do get a free walking trail guide, which has numbered entries corresponding with stations along the walk. Raccoons, egrets and herons hunt the edges of Logan Creek here, and black-tailed deer and Jack rabbits can lurk in the trees. You might see pond turtles, fence lizards and king snakes. Allow an hour for the walk.

This wouldn't be here without the water. The historic wetlands were a winter haven for millions of ducks, geese and swans from as far away as Canada, Alaska and even Siberia. But by the early 1900s most of the habitat was gone, converted to agriculture.

Alarmed by crashing bird populations and seeking to mitigate crop losses caused by waterfowl feeding in the area's rice fields, President Roosevelt and the U.S. Fish and Wildlife Service in 1937 created the Sacramento National Wildlife Refuge between the towns of Willows and Maxwell. They were carved out in part from the former Spaulding Ranch largely by the labor of the Depression-era Civilian Conservations Corps.

Over the years, other small refuges were created in the area, and today the Sacramento NWR complex includes five refuges and one wildlife management area totaling about 35,000 acres. Although it's only a small portion of what was once here, it's the single most important wintering area for waterfowl along the Pacific Flyway, hosting 2 million ducks and a million geese each winter.

We set out to see as many birds as we could in an hour and wound up spending more than two hours on the auto tour route alone. Bring binoculars and a spotting scope if you can. Creeping east toward the viewing platform, you keep coming across openings in the vegetation around the ponds that yield great views of thousands of ducks and geese.

Northern shovelers were everywhere during our visit, with mallards and elegant little northern pintails mixed in. American widgeon (although none of their Eurasian cousins this day), green-winged teal, ring-billed ducks, gadwall and eye-popping cinnamon teal paddled about or preened on the banks of the ponds.

It's not just waterfowl, of course. Red-tailed hawks soared high, and northern harriers swooped low over the marshes to do lunch, tell-tale white rumps flashing in the sun. Birds along the road included white-crowned sparrows, killdeer, the occasional black phoebe and surprising numbers of western meadowlarks.

The viewing platform was the climax of the tour, with thousands of Ross's geese and snow geese crowding the ponds. The birds are hard to tell apart at first, but you quickly become adept at it. The larger snow goose has a black "grin patch" on its strongly curved bill. The Ross's has a smaller bill with no grin.

We also saw the "blue" snow goose, a darker morp, and lots of greater white-fronted geese. Another goose abundantly present was the cackling goose, a shorter-necked subspecies of the familiar Canada goose. Throw in a few swimming bufflehead, hundreds of black-necked stilts probing the shallow water with their long bills, common moore-hens and a lone Cooper's hawk swooping around and, well, you get the idea. We saw about 40 species, a number that could easily have gone up with a little more time.

Reach freelance writer Bill Varble at