A black-and-white warbler 'feaking,' a term used by birders to describe the act of a bird wiping its bill on a branch. Credit: Courtesy of Bob Duchesne

Feaking. I had never heard the word before. At the end of the day during one of my summer birding tours, we were sitting around the dinner table, amusing ourselves with birding terms that most people wouldn’t recognize, including me.

Feaking is a word that first came into use among falconers. It describes the act of a raptor wiping its bill on an object, usually to clean it after eating. Although it’s common and easy to see among raptors, bill-wiping is also a behavior you can witness in your own backyard. For instance, birds that visit your suet feeder often pause to wipe the sticky stuff off. Household pets, such as parrots, do it.

If bill-cleaning was the only reason for the behavior, this column would already be over. But many birds have been observed scraping their bills, even when their bills aren’t dirty. Apparently, there’s more to the story.

A bird’s bill is made of keratin, the same substance found in human hair and fingernails. Because the bill wears down with use, it continues to grow. Predatory and seed-eating birds must pay particular attention to bill maintenance, in order to keep their beaks in proper shape for tearing and cracking difficult food. But all birds likely have to pay some attention to the task. Well … maybe not ducks. I’ve never seen a duck do it. Apparently, no one has.

More reasons for bill-wiping: some birds change diets during the year, eating insects in summer, then switching to seeds and fruit in winter. There is some observational evidence that these species fine-tune the shape and abrasion of their bills to adapt to their changing food supply. Granted, there hasn’t been a lot of study on this. There are more important things to research, so bill-wiping remains an understudied curiosity. That’s why we still don’t really know much about a third possible reason.

Some romantically inclined birds may be wiping their bills for courtship purposes. Birds have oil glands for preening their feathers. They distribute the oil with their bills. There is some evidence that this preening oil contains chemicals that send scent signals to potential mates. To increase his attractiveness, the male also wipes oil onto nearby branches with his bill. In one experiment, male dark-eyed juncos were filmed wiping their bills more often in the presence of females during breeding season.

Ironically, the bill-wiping behavior I see most often is the one least described by science. Many birds, including backyard birds, wipe their bills on a branch when their activity is disrupted, possibly to show annoyance at being displaced from what they were doing. I see it happen when I flush a bird from the ground or bird feeder.

I also see it happen when I attract songbirds by making noises to get their attention, also known as “pishing.” Although the term describes various squeaks and whistles made by birders, the typical noise is an aspirated “pish-pish” sound that mimics the mobbing calls made by chickadees and titmice.

Chickadees and titmice are particularly prone to raising the alarm when a threat is present. They are the first to mobilize a mob of fellow birds to confront a predator. Their calls are a universal language understood by all birds. Thus, when a birder mimics the sound of a chickadee by pursing lips and blowing “pish-pish-pish” in the cadence of the chickadees, many species will come take a look to see what’s going on. Pete Dunne, famous bird author and recent Maine transplant, even wrote a book about it, called “The Art of Pishing: How To Attract Birds By Mimicking Their Calls.” Pete is a wicked pisher.

Of course, pishing is disruptive to birds and should be done judiciously. Whenever I do it, I note that the birds sometimes come to a branch near me and wipe their bills to show their annoyance, or maybe territorial defensiveness. Some birds are known to do it to each other as an aggressive warning sign, wiping their bills as if sharpening a weapon.

By now, parrot owners are probably snickering at this column. Many pet birds are not shy about showing who they like and don’t like, and they have many ways of expressing it, including biting. Annoyed bill-wiping is another common signal.

I see this bill-wiping behavior more often during breeding season, when songbirds are focused on mating and chick-raising. Nonetheless, I see it year round, and I invite you to look for it. Birds are fun to watch. Bird behavior is fascinating.

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.

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Bob Duchesne, Good Birding

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.