BIRDS WASHING FOOD [Ref]
We not only wash ourselves and our clothes, but certain items of our food are regularly washed, as spinach, to get the sand out of it. Washing has been so important in our society that we've coined the term "Cleanliness is next to godliness." Possibly we've the snobbish idea it's a strictly human trait. Among other animals we don't expect to find water used for such cleanliness, and the raccoon, who does wash his food, is considered a sort of biological oddity.
But when we come to birds we find a surprising number of them that wash their food.
The dipper of our Western mountains in Oregon has been seen to wash insects and grubs before feeding them to the young birds. The parents held the food crosswise in the bill and the head was twisted rapidly from side to side in the water. Not until then was the food taken to the nest for the young.
The scene shifts to Africa. Four buff-backed herons were feeding on a flooded lawn at Gezira, Egypt. One of the birds captured a large insect, apparently a large black beetle. Holding the insect in the tip of its bill, the bird walked to the water, immersed the beetle three times, shaking and fumbling with it the while, and then swallowing it.
Then in Britain came a whole host of records, after an observation in Holland in 1946 of curlew sandpipers washing food. The birds were probing the dry mud at the edge of a little creek. When one of the birds got a small sand worm, it at once ran with quick steps to the creek and stepped into the shallow water, where it dipped the worm a few times into the water before swallowing it. Then it trotted away for more. The editor of British Birds, the journal in which this was published, suggested that this might be a more common habit than the scanty published records would indicate, and invited observations.
A spate of records resulted in the succeeding numbers of the journal: a whimbrel washing crabs; a snipe, earthworms; godwits washing their food; with curlews it was reported to be normal; dunlins, greenshanks, redshanks, ringed plover, and oyster catchers were all reported doing this until it appears that with the group of birds we call shore birds—sandpipers, snipes, plovers, and their relatives—it may indeed be normal. The details of the observations strongly suggest that the reason for the washing, in many cases at least, is the same one that underlies our washing spinach; to get the sand and mud out of it.