My post on the ruddy duck last week raised a question from Jim T as to why birds that live in water need to bathe at all.
I wondered whether it was because their feathers were designed to repel water in the normal course of events, so they had to splish splash and fluff their feathers to clean their plumage and get water down to the skin. But I didn’t know.
So I checked with my Bird Expert, who checked with his Bird Expert, and it seems that my guess might be close to right. The purpose of bathing is to remove dirt and, possibly, parasites from their feathers. Ducks and other water birds might not get that wet, just sitting in water or even diving, so they need to splash and fluff simultaneously to get truly wet and, therefore, clean.
But wait, there’s more.
After a land bird “bathes” in a bird bath, they always fly to a perch and undertake a substantial amount of preening. Preening can “zip” feathers together again (a feather surface is held together by hooks and barbs likened to Velcro). Preening “re-zips” the Velcro.