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Pileated Woodpecker Feeding Hole Embellishment

3-2-15  pileated horizontal lines 057Large rectangular excavations in trees, indicating Pileated Woodpecker feeding activity, are relatively common. These holes give the woodpecker access to carpenter ants living in galleries within the tree. What are not common are the horizontal lines radiating out from either side of the top rectangular Pileated Woodpecker feeding hole (and, more subtly, the bottom two holes) in the pictured tree.

Pileated Woodpeckers use methods other than drilling rectangular holes to locate insects – they glean branches, trunks and logs, peck bark and scale bark off of trees. But these lines are unusual, to say the least. If anyone is familiar with this pattern, and would care to explain the function of these horizontal lines, it would be greatly appreciated. After racking my brain and checking several resources, I cannot come up with a plausible explanation, though inevitably there has to be one, for no pileated woodpecker, or any other creature, is about to waste precious energy, especially in a winter as cold as this one. (Thanks to photographer, naturalist and keen-eyed John Snell ( for finding and sharing this discovery with Naturally Curious.)

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45 responses

  1. Kit Pfeiffer

    Did some other creature make the scratch marks?


    March 2, 2015 at 8:06 am

  2. Suzanne

    Were the horizontal marks made before, after, or concurrently? I also wondered about other creatures, maybe knowing the pileated was onto something and coming to take advantage of exposed food? Or is a it a yellow bellied sapsucker hybrid (just kidding)? I’ve never seen this, and we have TONS of pileated sign in our neighborhood.

    March 2, 2015 at 8:14 am

  3. Tom Durkin

    Could a second woodpecker have come after the pileated? A sapsucker? I have seen them make similar holes.

    March 2, 2015 at 8:28 am

  4. Chris

    The piliated’s brain is starting to freeze up because it’s been so darn cold!

    March 2, 2015 at 8:36 am

  5. Penny March

    Perhaps the wounding of the bark around the hole will produce resin/sap that would catch remaining ants that might venture out to check the damage. Red-breasted Nuthatch do resin-decorating around their nest entrance to keep insects out. This might be a reverse method—particularly if the bird heard more activity in the tree.

    March 2, 2015 at 9:07 am

  6. Roseanne Saalfield

    Mary Are the hole and scratch marks low enough for a bear or porcupine to reach or are u absolutely certain the marks were made by the bird? I’m in Florida and heading toward Sanibel Island in a few days for some birding . I’ll show this photo to some ranger naturalist types Love a good mystery


    Sent from my iPhone


    March 2, 2015 at 9:16 am

    • Thanks, Roseanne. Both holes and horizontal lines were definitely made by a pileated woodpecker (possibly/presumably the same one?).

      March 2, 2015 at 12:25 pm

  7. Susan Musty

    Do you think this might be the woodpecker doing all this back and forth to sound out where the thinnest point is to get to the ants? A method of conserving energy in the long run?

    March 2, 2015 at 9:19 am

    • Yes, that is possible, Susan, but if so, you would think you would see this pattern regularly at pileated holes…very mysterious!

      March 2, 2015 at 12:14 pm

  8. janetpesaturo

    So interesting, Mary! I’ve never seen anything like this, and what’s really fascinating is that it appears that the old holes beneath the freshly pecked one also show that the same horizontal lines were made. Leads me to think that there is some insect living right under the bark that the bird detected as it pecked for carpenter ants. I don’t have a clue what it is. Have you asked Charley Eisman? He may know.

    Is that a red pine, by the way?

    March 2, 2015 at 9:20 am

    • Yes, a red pine, Janet! Charley Eisman’s a great idea!

      March 2, 2015 at 12:26 pm

  9. Here is a link to another blog post in which it seems a pileated woodpecker made horizontal lines on a trunk in the process of complete removal of bark from a dead tree:

    March 2, 2015 at 9:28 am

    • Thanks, Wendy. I’ve seen those horizontal lines when a woodpecker is sloughing, or removing all the bark, but never in the pattern that these holes have!

      March 2, 2015 at 11:42 am

  10. King Heiple

    Mary: Woodpecker bills continue to grow during life. I would think since they obviously wear! As a woodworker myself I would suspect that those marks are “bill sharpening” marks! King Heiple 28 Peppercreek Dr. Pepper Pike, OH 44124 Ph: 216.464.2083 email:

    March 2, 2015 at 9:29 am

    • Plausible, but then why wouldn’t any other pileated holes I’ve ever seen have them?

      March 2, 2015 at 12:13 pm

  11. Bruce curtis-mclane

    Maybe creating noise/vibrations to chase outlying ants into the center hole?

    Bruce Curtis-McLane Jackson, NH

    On Mon, Mar 2, 2015 at 8:01 AM, Naturally Curious with Mary Holland wrote:

    > Mary Holland posted: “Large rectangular excavations in trees, > indicating Pileated Woodpecker feeding activity, are relatively common. > These holes give the woodpecker access to carpenter ants living in > galleries within the tree. What are not common are the horizontal lines > rad”

    March 2, 2015 at 10:09 am

  12. Bruce Curtis-McLane, Jackson NH

    Maybe creating noise/vibrations to chase outlying ants into the center hole?

    March 2, 2015 at 10:10 am

  13. I agree. Woodpecker; not bear or porcupine.
    We have some trees that I really don’t know why they are standing because there are so many pileated holes. Can’t get the photo now because of un-working server. 😦

    March 2, 2015 at 10:16 am

  14. Sondra Gingery

    I found this when looking this up. I didn’t find any other type of animal besides woodpeckers that do this neatly aligned horizontal work. We have pileated woodpeckers in our property in the U.P. of Mich. I will be looking for this when we are there this spring. We do also have several smaller species as well, so I won’t be able to tell for sure.

    March 2, 2015 at 10:23 am

    • That’s the closest anyone has come to this pattern, Sondra. Thanks so much.

      March 2, 2015 at 11:44 am

  15. Suzanne

    Interesting link, Wendy Weiger. I also wonder if the horizontal lines could be a strategy for looking for the best place to “dig” – i.e. kind of a survey of the condition of the wood, and maybe then the pileated zeroes in on the place to make a hole/dig deeper. Just a guess — no evidence.

    March 2, 2015 at 10:23 am

    • Sounds plausible, Suzanne, but I wonder if that’s the case, why don’t pileateds do this regularly?

      March 2, 2015 at 11:44 am

  16. K.P. McFarland

    Both this species and the Ivory-billled Woodpecker are well known for scaling bark to expose ant tunnels. The Birds of North America account says:
    “Pries off long slivers of wood to expose ant galleries.”
    “scales bark off trees” I am guessing that is what was going on here.

    March 2, 2015 at 10:36 am

    • You’re probably right, Kent, but it does seem odd that they are around all three holes, yet I’ve never seen this regular pattern of scaling on any other pileated hole.

      March 2, 2015 at 11:46 am

  17. Bill On The Hill...

    Hi Mary… I would concur with Suzanne above & it appears to be looking for weak spots in the bark. I see the humble beginnings of a ” Masterpiece “…
    Great post, BF

    March 2, 2015 at 11:36 am

  18. H. Kennedy

    maybe –

    March 2, 2015 at 11:42 am

    • Thanks so much. Yellow-bellied sapsuckers do make horizontal lines, but they consist of tiny holes, one right next to the other, not a continuous removal of bark. But a great thought!

      March 2, 2015 at 12:11 pm

  19. Bob and Inge

    Dear Mary,

    I have not been getting photos with the last two posts. Is it something I am not doing? I normally get them, although I have missed them in the past, also.

    Sincerely, Inge

    March 2, 2015 at 12:27 pm

  20. Hi Inge,
    I’m afraid WordPress is the one that can help you — I don’t have the ability to fix anything from my end. It’s impossible to get them on the phone, so I usually go to and try to find someone who can answer my question! Good luck.

    March 2, 2015 at 12:30 pm

  21. Kathie Fiveash

    Could this be an aberrant individual? I wonder whether a mutation could cause a different pattern of drilling, which might or might not be advantageous to the individual. Like you, I have seen lots of pileated feeding holes, and never anything like this. Pileated woodpeckers are territorial, and it would make sense that if an unusual individual made this kind of pattern once, he/she might do so routinely in other trees in his/her territory. It makes sense that the same woodpecker would revisit a productive tree in its territory. This tree has clearly been revisited. I wonder if John Snell looked carefully in the same area, he might find other similar holes. I guess another possibility is some unusual feature of that particular red pine or its insect inhabitants. .

    March 2, 2015 at 12:54 pm

  22. Rachael Cohen

    Mark Elbroch’s book “Bird Tracks & Sign” has a photo of bark sloughing with horizontal beak marks made by a three-toed woodpecker (p. 251; available in preview on google books). A similar photo appears on the Alderleaf Wilderness College website in an article called “Recognizing Woodpecker Habitat” ( This doesn’t look much like your photo, but perhaps the mechanism is similar?

    March 2, 2015 at 3:37 pm

    • Thanks, Rachael. I think you’re probably right – I’ve just never seen it limited to either side of a feeding hole, or just individual lines of bark removed, but what else could it be? Many thanks!

      March 4, 2015 at 8:19 am

      • Suzanne

        It is weird… of the hundreds of pileated sign I’ve seen, I’ve never seen this pattern. But you can be sure I’ll be especially examining holes for any hints of it now! No red pines around here. They seem to go mostly for the old sugar maples, oaks, and beeches.

        March 4, 2015 at 8:28 am

  23. David Putnam

    I can only guess that they probe horizontally and this tree was so good that it just couldn’t decide where to start the hole.  PS — fresh fox tracks on the pond yesterday, but not from the den . . .

    March 2, 2015 at 6:40 pm

  24. Anne \Taffy\ Taferner

    I am seeing a very small bird, travelling in groups of 20-30, mostly in open fields in Northern Maine. I can’t get close enough to get a good look at them as they take off when you get within 50′ of them. They have a white underbelly & dark wings & when they fly off any distance they disappear from sight. Can anyone tell me what they might be as I can not find them in my bird guide. Thank you!

    On Mon, Mar 2, 2015 at 8:01 AM, Naturally Curious with Mary Holland wrote:

    > Mary Holland posted: “Large rectangular excavations in trees, > indicating Pileated Woodpecker feeding activity, are relatively common. > These holes give the woodpecker access to carpenter ants living in > galleries within the tree. What are not common are the horizontal lines > rad”

    March 3, 2015 at 1:28 pm

  25. OK, I am going to go out on a limb here, pun intended, and suggest this has something to do with red pine being the subject practiced upon: Could PWP be simply beating out a pattern that makes it easier as he expands his hole? Sort of like when you fold paper on the dotted line to make it easier to tear or cut? PWP takes off the outer layer first then the next layers are easier to work on. Do you have a lot of Red Pine where you live Mary? I don’t here in western central NH, but it looks as though the scales on red pine would be harder to peck through than the thin, fairly soft outer bark of White Pine.

    March 3, 2015 at 5:45 pm

    • That’s a fascinating theory, Helen, and one well worth considering. I’m afraid we’ll never know for sure, but thank you – sounds plausible to me!

      March 4, 2015 at 8:20 am

  26. Catherine Fisher

    Hi Mary,
    Hairy woodpeckers often peel bark from trees (most often in winter), and have been observed following pileated woodpeckers in order to glean from their excavations. They’ll forage in the pileated cavity itself, but also peel bark from around the excavation. Perhaps this is what caused these cool embellishments.

    March 6, 2015 at 9:37 am

    • Thanks, Catherine. I didn’t know about this hairy woodpecker behavior!

      March 6, 2015 at 11:43 am


    I have evidence/pics of an almost identical pattern. I thought they were bear claw marks, but everybody I ask disagrees with that.

    March 29, 2018 at 12:23 am

    • I’m afraid I agree with the disagree-ers! It like any bear marks I’ve seen!

      March 29, 2018 at 12:15 pm

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