The Life of a Sapsucker

Last November26, I walked into our sunroom. Almost immediately I spotted a male yellow-bellied sapsucker eating the fruit of one of two hackberry trees we had planted more than a decade ago. Also called “sugarberry,” it is known to be a favorite winter food for a variety of songbirds, most notably American robins and yellow-bellied sapsuckers.

I had a bird’s eye view of this unusual woodpecker from our sunroom, which is perched on a hillock surrounded by black walnuts, black locusts, scarlet oaks, and a white pine. As I watched the sapsucker, he plucked and ate several hackberries and then flew down into the dead middle tree of the three large front yard black locusts and tapped away.

Next he flew to a black walnut tree branch outside the sunroom and probed in a crevice. Every time he withdrew his bill he had food in it that he swallowed so he was probably searching for and eating insects. Finally, he hitched his way past the crevice and began drilling small sap holes, but after a couple minutes he flew away.

As close as I had been to the sapsucker, I could not be certain what he was doing once he left the hackberry tree, but I could verify his attraction to hackberries. Since the weather had been mild, he was lingering later than the usual sapsucker migration period in Pennsylvania of late September through October. Or perhaps he planned to stay for the winter on our 1500-foot mountaintop as an occasional sapsucker has in the 47 years we’ve lived here.

Male yellow-bellied sapsuckers don’t migrate as far south as the females, although most yellow-bellied sapsuckers migrate from their northern nesting grounds of southeast Alaska, the southern half of Canada, and our northern states where they breed as far south in the east as Pennsylvania’s northern tier. A few winter mostly in the southern part of the commonwealth, but the yellow-bellied sapsucker—the only woodpecker species in eastern North America that is completely migratory—usually spends its winter farther south in the United States, West Indies, Mexico or Central America.

As their name suggests, both the male and female yellow-bellied sapsuckers have dull, yellow bellies and breasts in addition to red crowns and black faces, wings, and backs accented by white patterning—two horizontal stripes on their faces, a broad patch on each wing, and stippling on their backs. But only the males have flaming red throats.

Because they sapsuck, they are nicknamed “sap-sippers” and “sup-saps,” and lap up leaking sap and any trapped insects with their specialized, brush-tipped tongues. Although they have drilled their sap wells in more than 1000 tree and woody plant species, they prefer sick or wounded paper and yellow birches, red and sugar maples and hickories, all of which have high sugar concentrations in their sap.

In early spring they drill holes in xylem, the inner part of the trees, to obtain sap moving up the branches, but after trees leaf out, they drill shallow, rectangular wells in phloem, the part of the tree that carries sap down from the leaves. That sap may be 10% sugar and feeds not only sapsuckers but ruby-throated hummingbirds, which time their migration to that of sapsuckers to make use of this abundant resource. Tufted titmice, white-breasted nuthatches, black-capped chickadees, red-bellied and downy woodpeckers, and black-throated blue warblers have also sampled the flowing sap as well as bald-faced hornets, paper wasps, chipmunks, red squirrels, bats, porcupines, and martens.

While sap comprises about 20% of their yearly diet, they also eat a wide variety of insects, not only those trapped in the sap, but those they pry from under bark scales and catch in the air. Bast, the inner bark and cambium layers of trees, fruit, including berries of dogwood, black alder, Virginia creeper and wild black cherries, buds (in spring) and seeds complete their varied yearly diet.

Yellow-bellied sapsuckers begin returning to Pennsylvania by the third or fourth week in March. Here on our ridge-and-valley mountain, I first know they are back when I hear their peculiar mewing alarm calls sometime in early April. Then I find them quietly tapping and tippling in our woods. Usually they are males because they migrate a week ahead of the females. And here they seem to favor hickory trees which are already scarred with rows of old sapsucker holes. Hickory trees, it turns out, have a sap flow with a sugar concentration of between 6.4% and 11.1%.

One April day I watched two males flying at each other around a medium-sized hickory tree, fighting over possession of a favorite tippling tree. I settled down to watch as one quickly routed the other and started to “sap-sip.” He braced his tail against the tree at a 45 degree angle, gripped the bark with his feet, and dipped his beak into each hole two or three times. Each time he withdrew his bill it glistened with sap. Twice he had to stop and defend the tree from the other sapsucker before both birds flew off.

On another April day I watched a male sapsucker sipping sap from a huge old sugar maple tree above the Far Field Road. That tree had old and new sapsucker holes, and he drilled new ones as I watched, The flowing sap also fed flies but instead of eating them, he made a quick dive to the ground, plucked up an insect, and flew back to his original perch.

He occasionally glanced at me as I sat on the ground six feet away, but he continued his drilling and sipping. The latter he did by turning his head sideways and dipping his beak into each hole two or three times, being careful not to touch the sticky bark with any other part of his body except his feet and the tip of his tail.

He also defecated a fine stream every three minutes by quickly lifting his tail away from the bark and squirting a good foot or so from the tree. In his Woodpeckers of Eastern North America, Lawrence Kilham wrote of watching a sapsucker drilling in a black walnut tree during a January thaw in Washington, D.C. He noted that in a 25 minute period, one sapsucker voided 11 times or once every two minutes.

I didn’t hear the distinctive irregular drumming of a sapsucker. Mostly they drum on their breeding grounds to defend their territory and especially their sapsucking sites. Here in Pennsylvania they breed in the forests of our northern tier with 44% of our state’s estimated 96,000 birds in Warren, McKean, Potter and Tioga counties alone.

According to biologist Bernd Heinrich in his One Wild Bird at a Time, “the male drumming attracts the female, and that when she arrives he leads her to his previously found nest site [in a tree with hardwood decay fungus]. If she approves, she lets him know by offering token help, and then he begins excavating in earnest.”

Sapsuckers are monogamous during their breeding time and often from year to year because they frequently return to the same breeding site, tree, and even cavity as the previous year. While he takes two to three weeks to drill a new nest cavity, she spends her time preening and resting. The entrance hole is a tight 1.5 inches and the nest cavity as deep as 10 inches.

She lays five to seven white eggs on a bed of wood chips left over from cavity construction and both parents incubate them with the male taking on some of the day hours in addition to the night shift. After 10 to 13 days, the naked hatchings emerge. The parents take turns brooding their young and feeding them insects often coated in sap.

Most nests are 9.8 to 45.9 feet from the ground and the nestlings are noisy which may attract predators. Kilham reported weasel predation in nests he observed in New Hampshire. Other predators include raccoons, snakes, red squirrels, hawks and black bears.

At 25 to 30 days old, the young fledge but continue with their parents who feed them for a week and teach them sapsucking. The fledglings quickly learn to capture insects in the sap wells, but even after they feed themselves, they keep in vocal contact with their parents and use their sap wells. About six weeks out of the nest, they can drill their own sap wells but appear to stay in family groups at least until migration.

Yellow-bellied sapsuckers have been increasing throughout their range according to the 2011 Breeding Bird Survey. In Pennsylvania between the first and second breeding bird atlasing, breeding increased 99 percent Scott H. Stoleson reported in the Second Atlas of Breeding Birds in Pennsylvania. Although sapsuckers did not increase in the Allegheny Mountains where they once bred, they filled in and expanded in the northern, eastern, and western sections of Pennsylvania. Thus we can rejoice that such a unique woodpecker thrives in the commonwealth.