Monday, January 27, 2014

Mystery Lines on a Dead Tree

What's up at Fellows Lake? - Norm Youngsteadt
Jean Youngsteadt sent me some pictures of a dead tree along the Fellows Lake Trail.  It had been bark covered the week before and now was thoroughly chewed off all the way up.  The flakes and damage looked like the work of a woodpecker.  The puzzling part was the horizontal lines across the trunk as seen below.

Horizontal lines across the trunk
I was still betting on a pileated woodpecker.  I can still recall looking out of our front door at the creek and seeing large wood chips flying up a foot in the air above a large tree stump we had cut for a seat around the fire ring.  Eventually a pileated woodpecker hopped up on the stump with all the confidence of his cousin Woody, looked around for predators, then hopped back down behind the stump and the wood chip bombardment resumed.  He finished it within an hour.

I had seen the same thing along the creek last week.  The tree below had been bark covered a week earlier and now there was a foot deep pile of wood chips on the ground and large cavities in the soft trunk.

We still hadn't answered the question about the horizontal lines of damage which I hadn't seen before.  I sent the pictures to our Fabulous Forester, Frances Main and she quickly replied.
"This is woodpecker art. Pileated would be a good guess because the chips are so big and it goes down so close to the ground. I had another photo like this sent to me just in the last week or two, so the poor birds must be getting really hungry in this cold weather!

The horizontal lines we are seeing is pretty common with woodpeckers…they get a little lazy about moving, so work one spot moving just their head. From the first picture, you can tell there were plenty of bugs in there! I bet he had a good time and left full : )"
Although a pileated woodpecker's primary diet is carpenter ants, they also eat other ants, woodboring beetle larvae, termites and other insects when the opportunity arises, as well as fruit and nuts. They are even attacking emerald ash borer larvae, the subject of a pending blog.

The good news is that in digging holes in trees, the woodpecker is serving as a home builder.  Over 38 species of birds and mammals use the woodpecker's feeding and nesting cavities for their own nests or shelter.
"In a study in Alberta, Canada, 54% of 878 pileated cavities showed evidence of use by at least one secondary cavity nester. A secondary cavity nester is a cavity-nesting bird like a bluebird or screech-owl that is unable to excavate its own nest cavity. It must find pre-existing natural tree cavities excavated by woodpeckers, or nest boxes provided by people."  Much more information is at this site.
If you have a woodlot, try to leave 1 to 3 large standing dead trees per acre.  Your critters will love you for it.

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