Blane Klemek: Tap-a-tap: yellow-bellied sapsuckers have returned from down south
A few mornings ago on one of the few and warm, pleasant mornings that we have been able to enjoy this April, I was assessing the aftermath of winter and its affect on the woodland I live within.
I had already completed the wood duck and bluebird nest box chores a few weeks ago, so that job was done; now all that remained was to await hopeful occupancy, which was soon confirmed when I passed beneath one of the wood duck houses - a kestrel flew out of it!
What was also discovered, much to my dismay, was the amount of damage that one hungry deer can inflict on a few dozen red and white pine seedlings.
No one was to blame other than me, for I failed to put cages around all of the little trees last fall. Instead, I opted for paper bud caps stapled around each of the trees' terminal leaders.
Lo and behold, though no surprise, a single deer had moseyed amongst my scattered pines and systematically lopped my tiny trees as if the animal possessed pruning shears. I knew better, of course, because that's what deer do - they browse. Still, as any forester can attest, too many deer - or in this case, one - can be the bane of trees and other woody vegetation.
On the subject of sometimes-pest wildlife, I stopped for a woodland "shout out," so to speak. I was interested in finding out if one particular species of woodpecker had arrived in the Northland yet. So, with a stout stick in my hand, I hammered out the telltale territorial tap of the male yellow-bellied woodpecker against an aspen tree, stopped for a moment, and listened. A few seconds later I received a reply: a nearby male yellow-bellied sapsucker, using a wood duck nest box as his sounding board, countered my rendition with the real McCoy.
"They're back, too," I thought, smiling.
Yellow-bellied sapsuckers migrate north to our neck of the woods every spring from as far away as Central America, Mexico and southern United States. As their name so aptly suggests, "yellow bellies" are indeed sapsuckers and, in Minnesota - as we all well know - sap doesn't run in the wintertime. Hence, the primary reason they head south come fall.
In any event, yellow-bellied sapsuckers have the unique habit of drinking sap from favorite trees such as paper birch, box elder, and mountain ash. Sapsuckers are known to tap more than 250 different species of trees and vines. They accomplish "sap-sucking" by drilling "sap wells" in neat rows or columns on tree trunks and branches. Once holes have been created through the bark, the birds eat away the inner bark and cambium layer and drink the sap that flows from the wells.
As expected, sapsuckers are not quite so endearing to many people. The yellow-bellied sapsucker, quite numerous locally in woodlands and orchards throughout the state, are indeed the critters responsible for the puzzling rows of small holes that people often observe encircling the trunks of their favorite trees, sometimes even killing trees.
Why all the tiny holes? Sapsuckers love to consume the sap of trees and so they "drill" holes through the bark causing the sweet liquid sap to ooze out of the holes. And though called a sapsucker, the yellow-bellied sapsucker really doesn't "suck" sap at all. What the bird really does is to stick its brush-like tongue into the sap-filled holes to eat the sap and any insects that might be trapped in it too.
As mentioned above, yellow-bellied sapsuckers also eat insects that are attracted to the sap. The birds also forage for insects in manners typical of other species of woodpeckers through probing, prying, and pecking into dead or live wood with their bills. Sapsuckers also consume fruit, berries and buds when in season.
Yet while sap makes up only about 20-percent of a sapsucker's diet, they won't stick around for very long when temperatures begin hovering at and below 32 degrees Fahrenheit. A sapsucker exodus from the North Country occurs every fall when colder temps slow the flow of sap. As well, during the springtime when freezing temperatures prevail, sapsuckers have to rely more on foods other than sap to survive.
Obviously, when the annual freeze occurs in late autumn and trees no longer produce abundant, free-flowing sap and insects enter into dormancy, finding goodies to eat becomes next to impossible. Thus, all yellow-bellied sapsuckers migrate southerly from Minnesota until more suitable conditions are encountered for finding food.
But in the meantime, we have a whole spring, summer and fall to get through first. As such, right now, male sapsuckers are busy claiming their territories and will soon be joined by females, if not already, when nesting season will commence in earnest.
Listen closely and you'll soon be able to identify the taps of sapsuckers: "tap-a-tap-a-tap . . . a-tap, tap, tap" they go, often utilizing an array of preferred objects to strike with their beaks in order to produce optimum resonance, such as birdhouses, utility poles, and hard, dead limbs.
And so it is; the seasonal switch from cold and snow to warmth and growth is upon us. Birds galore have returned once again including the yellow-bellied sapsucker, in addition to many, many more of our avian neighbors for us to observe as we get out and enjoy the great outdoors.
Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at firstname.lastname@example.org