This Great Egret had dined recently. When hunting in water, the bird repeatedly dips its beak after finishing a meal. But on land, the bird doesn’t have any way to clean off that long beak, so it wears its recent feeding history on its face.
By the way, egrets and herons, contrary to a recent article in another venue, don’t use their beaks as spears. They don’t skewer their prey. Their beaks are pincers, used for grabbing, holding, tossing, squeezing and slimming their prey until it’s ready to swallow.
For a video of how the bird does it, check out Great Egret Has Success. That’s in slow motion. For regular speed, view The Last Three Minutes. There’s more than a little cat-with-mouse action involved.