While spring migration won't be in full swing for a number of species for a few weeks, Sandhill Cranes are already on the move. We typically get about 25,000 Sandhill Cranes in California each year, and these birds have been wintering for the most part in California's Central Valley. As you read this, the birds are taking off and heading north for breeding grounds both near and far. Here's some video that someone caught just last week of the big birds flying over Auburn on their trip north:

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More video and maps about Sandhill Crane migration below the fold.

Here's a January 2012 map from eBird that shows where the birds have been spending their winter in the Central Valley:

Here some great video showing the birds wintering in Lodi:

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As you can see from the most recent map showing far few sightings, the Sandhill Cranes are moving out:

So where are all these Sandhill Cranes going? For the most part, the cranes are headed off to breeding grounds in the north. Some, like the Greater  Sandhill Crane, will head for Northeastern California (where Audubon California has been working with private landowners in the Surprise Valley to protect Greater Sandhill Crane breeding habitat), and other parts of the Pacific Northwest.  Other Sandhills will go further north into Canada and Alaska (where Audubon Alaska is working hard to protect critical habitat in places such as the Arctic National Wildlife Refuge.  What does all that look like? Well, something like this eBird map from August 2011:

Note the concentration of birds in the Pacific Northwest and Alaska. They'll stay there until October, when they'll head back to California's Central Valley.

In Alaska, the Creamer's Field Important Bird Area in the heart of Fairbanks, Alaska, is known as a Sandhill Crane migration staging area in both spring and fall. In fact, the Tanana Valley Sandhill Crane Festival, which the Arctic Audubon Chapter helps organize along with the Alaska Bird Observatory, celebrates the arrival of up to 2,000 cranes in late August every year.

Family groups of Sandhill Cranes migrate together. At Creamer’s Field, you can often see a pair of adult cranes followed by one or two rusty-colored “colts” striding across a field. The young birds don’t have their brilliant red crowns yet, and their vocal cords are not fully developed. This Important Bird Area is one of the few places you can hear the trilling, high-pitched calls of young cranes in harmony with the deeper trumpeting of adults.