One thing people don't realize about refuges is that they are not wilderness areas. They are actually carefully managed and actively modified to simulate the kind of habitat the birds they're managed for need. Here is a field that's been strategically burned to remove some of the brush. Soon it will be flooded, and this creates a mud bottom that will be used by many of the shorebirds and ducks that are coming to the habitat for the winter.
San Luis National Wildlife Refuge, California
CaliforniaMerced CountySan Luis National Wildlife Refugegallery_central_valley
From 2013 Images