Picture this Gadwall duckling swimming slowly across a pond, skimming the water’s surface with its broad, spatulate bill. This behavior is called dabbling. Along with the pond water, multitudes of tiny particles pass through the duck’s bill. Somehow it sorts out and swallows the edible seeds and invertebrates, while rejecting the tiny, inedible bits of grit, mud, and debris. To see how a duck pulls this off, we need to pry its bill open and look carefully inside. More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.