Thousands of Sandhill Cranes have converged on Colorado's Monte Vista National Wildlife Refuge for a stopover before they head north.

Each spring about 20,000 of the winged creatures take a respite at the refuge, the Rocky Mountain News reported Sunday.

The birds feed on barley and wheat and roost in open water at night, from late February through mid-April. After leaving the refuge, many of the birds begin their 850-mile trip to summer breeding grounds, often in the greater Yellowstone area -- including Grays Lake National Wildlife Refuge in Idaho -- or points farther north, the newspaper said.

The birds will return to southern Colorado again in September on their way to New Mexico and points south for the winter.

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