Wading through knee-deep water, Kelly McKay squinted in the evening light as the sun began to dip below the horizon. All around him, herons and other migratory birds darted between the dead trees that rose above the water, while turtles took shelter in the marsh’s tall grasses.

This is the Milan Bottoms, a massive wetland near the conjunction of the Rock and Mississippi rivers in western Illinois that’s home to over 150 endangered and threatened species. It’s also the largest known winter nighttime roost for migrating bald eagles in the lower 48 states.

Over the past year, McKay, a biologist who has done contract work with the U.S. Army Corps of Engineers and several state Departments of Natural Resources, has spent hundreds of hours documenting the wetland’s wildlife in his free time.

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