Here's Why Birds Rub Their Beaks on Stuff

[Judi Lynn]

There’s more to this behavior than meets the eye. Some of it meets the nose.

By Andy McGlashen
Associate Editor, Audubon Magazine
May 01, 2019



Bald Eagle mid-wipe. Photo: Maia Kennedy/Alamy

If you’ve spent much time observing birds—you clicked on this nerdy story, so that feels like a safe bet—you probably have noticed them wiping their bills on a tree branch or fencepost, or whatever else they’re perched on. And you might have wondered: What’s going on there?

A few things, it turns out. Bill-wiping is not the hottest topic in ornithology, but curiosity has drawn the occasional researcher to the behavior over the years. Although they haven’t arrived at a definite, universal explanation, we can summarize their reports on the role of bill-wiping this way: It definitely acts like a napkin, probably as a file, and maybe even as a cologne spritzer.

The first scientific paper to focus on the behavior, it seems, was a 1970 review by ornithologist George A. Clark, Jr. “Bill-wiping typically involves rapid withdrawal of the side of the beak from base to tip closely adjacent to a foreign surface such as a branch or the ground,” he wrote. “I have seen passerines wipe on rope clothesline, fence wire, the edge of a metal birdbath, and the rim of a metal incinerator.” While it often involves just a few swipes here and there, Clark cited one report of a finch wiping its beak 90 times in a few minutes. His research turned up more than 90 species known to engage in the activity, and he surmised that all birds do it, with the possible exceptions of hummingbirds and waterfowl. (Counterpoint: I dunno, this hummingbird sure seems to be wiping its bill.)

The napkin principle—that birds wipe their bills primarily to clean them—is generally agreed upon, based on logic and observation. “As widely noted, birds frequently bill-wipe after eating messy foods such as suet, fruits, or juicy insects,” Clark wrote. It just makes sense; you know how it is when you’re eating juicy insects. To make sure, though, researchers in the U.K. did an experiment and confirmed in a 1992 study that European Starlings wiped their bills more often after eating sticky food than dry food.

More:
https://www.audubon.org/news/heres-why-birds-rub-their-beaks-stuff?ms=digital-eng-email-ea-x-engagement_20190514_why-birds-rub-beaks_&utm_source=ea&utm_medium=email&utm_campaign=engagement_20190514_why-birds-rub-beaks&utm_content=

[RainCaster]

1. I've seen ducks do this with great consistency

I feed mallards in my pond every spring, and they will always clean off their beaks in this manner.

[UpInArms]

2. My chickens are

Bill wipers ...

It always seems they are cleaning their faces

[mopinko]

3. cool. my greys have def honed their beaks, but my zons

cant seem to get it done. never had to trim a grey's beak, but the zons need a regular trim or they can barely eat.
both have abrasive perches for their water dishes. they do swipe, but dont

the zons dont get the kind of chewing they would in the wild. i give them nuts in the shell, but they arent that good at it.
i think greys tend to have softer foods. def grow more slowly, and less engineered to flake away like the zons.

i believe the mating thing, too. part of their little dances that they do.