One of the best places to see them is at the Cosumnes River Preserve off Interstate 5 near the town of Galt. While most of the birds' historic habitat is gone, the preserve there is a major success story.
For millions of years, millions of birds flying north and south have counted on California's Central Valley for food and a place to rest.
"In the 1800s, the settlers talked about birds literally blotting out the sun and the noise being the same sound like you would hear like from a freight train," said Nature Conservancy scientist Mark Reynolds.
The white-fronted geese fly thousands of miles from the arctic to spend the winter at the conservancy. They swoop around looking for the perfect spot.
"The sound is really fantastic, and you are getting all the smells of the wetlands too," Reynolds said. "It's sort of an all-sensory birding experience."
But 95 percent of the wetlands the birds depend on are gone.
"Now it's really up to us to preserve the best parts of what's left," said Jesse Roseman with the Cosumnes River Preserve.
One of the best parts, the Cosumnes River Preserve, is 46,000 acres of prime real estate for birds.
"We saw them coming across the sky in little groups," said bird watcher Sheila Collins. "Just absolutely beautiful."
The preserve is a patchwork of properties owned by government and non-profit groups working together. The preserve is open to the public and is free for bird watching at its best and easiest.
"We've got...great birds right by the parking lot," Roseman said. "So you just show up and immediately, you see nature."
Roseman is the project director for the Nature Conservancy, one of the environmental groups that's made the place such a success. Part of that success comes from creative partnerships with farmers.
"Eighty percent of the preserve is agriculture," Roseman said.
In summer, the fields grow rice, corn and other crops. In the winter, they're flooded and turned into wetlands, just like nature used to do on its own. It's a perfect recipe for more than 200 kinds of birds.
Among the most spectacular are the huge sand hill cranes up to four feet tall with a wing span of up to six feet.
They're known for their elaborate courtship dances, and a lot of talking.
One couple drove from Albany to see them.
"It's like a wonderland," said bird watcher Ralph Pericoli.
Pericoli and his wife are veteran bird watchers, but even beginners should find it easy to spot the cranes.
"I had never seen them this close to the road," Pericoli said.
The big finale comes at sunset with a symphony of bird sounds with Mount Diablo in the background and cranes coming in to roost for the night.
"I find this really thrilling," said Reynolds. "It's a wildlife viewing experience on par with going to the Serengeti or going to the Galapagos, and it's right here in our back yard."
Right now is prime viewing season at the preserve. The drive is an hour or two from the Bay Area, depending on where you start. For directions and more details on the Cosumnes River Preserve, click here.
Written and produced by Jennifer Olney