Minnesota Outdoors: Yellow-bellied sapsuckers are a unique woodpecker, have just arrived

Submitted by Blane Klemek
Crookston Times

    In the world of woodpeckers—a group of birds that are normally year around residents of Minnesota—two species of woodpeckers spend only a few months here during the breeding and nesting season: yellow-bellied sapsuckers and northern flickers. This column is about just one of this duo—the yellow-bellied sapsucker.

    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.  And as their name suggests, a dash of yellow within its belly-plumage gives “yellow bellies” their descriptive name. These birds, though attractive, are often viewed unfavorably because of their interesting and sometimes destructive feeding behavior.

    Sapsuckers have the unique habit of drinking sap from over 250 species of trees, shrubs, and vines, including paper birch, box elder, and mountain ash. Here at my home southwest of Bemidji, yellow-bellied sapsuckers also peck holes and feed on the sap of trees and shrubs that include speckled alder, red maple, nannyberry, crabapple, Norway spruce, and lilac. They accomplish their “sap-sucking” by drilling “sap wells” in neat rows or columns on trunks and branches.  Once their precision holes have penetrated the outer bark, the birds continue excavating with their bills through the inner bark and cambium layer to drink the sap that flows freely from sap wells.

    As such, 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 birds responsible for the puzzling rows of small holes that people often observe encircling the trunks of their favorite trees, sometimes even killing trees.

    To illustrate this last point (that the actions of sapsuckers can kill trees), just last summer here at my home, a lone sapsucker singled out a three-inch diameter jack pine tree and began pecking its telltale rows of holes through the tree’s bark. In defense, the tree produced copious amounts of sap to plug the holes, but the sheer amount of holes surrounding the tree was too much in the end for the tree to withstand. Its green needles soon turned red.

    People often ask, “Why all the tiny holes?”  As mentioned, sapsuckers love to consume the sap of trees and so they "drill" holes through the bark, which causes 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/drink the sap and any insects that might be attracted or stuck in the sometimes sticky sap, too. Not surprisingly, the sweet sap produced from some trees such as maples and paper birch, attracts another bird—the ruby-throated hummingbird. I’ve often observed over the years hummingbirds drinking the sap that oozes from sapsuckers’ sap wells.   

    Yet while yellow-bellied sapsuckers will eat insects that are attracted to sap, the species also hunt for insects in ways that are typical of how other woodpeckers feed and forage by probing, prying, and pecking into dead and live wood with their bills. Sapsuckers also consume fruit, berries, buds, seeds, and other plant materials when in season.

    Although liquid sap makes up only about 20-percent of a sapsucker’s daily diet, they won’t stick around in Minnesota for very long come late summer and early autumn after 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. Conversely, during the springtime when freezing temperatures prevail as we’ve experienced this April, sapsuckers have to rely more on other foods rather than sap in order to survive.

    Yellow-bellied sapsuckers, having just arrived here in northwest Minnesota only recently, are a unique woodpecker to be sure. If you listen closely, you will hear the males’ distinctive territorial tapping on trees and other objects as they begin defending territories and searching for mates. Here for only a short period of time, yellow-bellied sapsuckers are among the many avian migrants to appreciate as we get out and enjoy the great outdoors.