As I was walking home today, I saw a group of American Robins hanging out in an open grassy yard. About 4 members of this group had moved near the curb and proceeded to give themselves baths in the water along the curb. Since it hasn’t rained, either someone had leaky sprinklers or else washed their car. Either way, I watched those little robins shaking their feathers in that water for a minute and thought to myself, “hmm…self…what do you know about bird baths?” In an interesting (and maybe surprising) way, bathing behaviors of birds in water don’t seem to be that well-studied. People put out bird baths in their yards, but (in my brief search today) I didn’t find much on the efficacy of bird baths. I mean, really, we watch them do it all the time, but we don’t know much about how well it works.
There are some detailed studies on how birds actually regulate the movements of bathing:
I love old-school ecology, ‘cuz they can say things like: “…the submergence becomes deeper, the rolling of body and flicking of wings more energetic – until the bird may welter in water…” Welter? Fantastic!
There’s another paper that deals with the effects of submersion on the feathers. Exposure to water can result in an overall decrease in the subsequent dry-weight of a feather, implying that some of the dust has been removed from the feather. No mention of parasites, but great and SIMPLE science! Take note students, it’s low-tech at its best!
Finally I came across another paper that did (in a correlative fashion) implicate the effects of parasites on bathing. In general, species that spend more time in preening and bathing tend to have higher parasite loads than species that have fewer parasites. So the big conclusion is, dirtier birds take more baths. Don’t be a dirty bird!