Nature Notes

What woodpecker is a sign of spring in our area? This one usually migrates, although the rest of “our” woodpeckers live here year-round. Increasingly, you might also see this woodpecker in winter, thanks probably to a warming climate.

Hint: This woodpecker’s name might seem like an insult if said of a person. No foul language is involved. If you haven’t yet guessed, it’s the yellow-bellied sapsucker (Sphyrapicus varius).

You won’t easily see the yellow belly. It’s hidden, but sometimes visible in flight. It’s a characteristic that was noted back in the days when people shot birds in order to identify them with a closer look. Fortunately, we now have binoculars and cameras, and native birds are protected by law (Migratory Bird Treaty Act).

Yellow-bellied sapsuckers look much like our other woodpeckers. They have a similar black-and-white color scheme. It’s hard to pick them out by size because they’re in-between a downy woodpecker and a hairy woodpecker. But on their sides, you can often see a white stripe on their folded wing. There’s a red forehead on females, and both a red throat and red forehead on males.

What about sapsucking? They forage on bark for insects, especially ants and spiders, but they’re famous for drilling “sapwell” holes in trees so they can eat sap – and the insects that come to it and get stuck. Sapsuckers typically spend about half their time near their sapwells, tending them and keeping them open.

What kinds of trees do they like? In winter you might find one locally, tending holes in pines. Later in spring when sap is flowing everywhere, watch for migrating sapsuckers near maples, birches, aspens, and hickory. Yellow-bellied sapsuckers prefer young, growing trees with abundant sap – saplings. They also frequent orchards for fruit. For digging nest holes, they like old but living trees, or trees infected with fungi that soften the wood. Old sapsucker nest holes often become homes for other animals.

You can tell that a yellow-bellied sapsucker might be around if you find sapwells on a tree-trunk. These holes are often in horizontal rows, with one row above another. Holes drilled early in spring are usually round, reaching deep into the tree for rising sap. Sapwells made later in the season are shallower and rectangular, to access sugar-laden sap being transported downward from leaves. Sapwells were recently pointed out during a Westborough Community Land Trust winter tracking walk at the MacCallum Wildlife Management Area.

Yellow-bellied sapsuckers lick up sap with brush-like tongues covered with forward-facing hairs. They also eat the inner bark of trees. While pecking out holes with their chisel-like beaks, they brace themselves with their stiff tail feathers and grasp the bark with feet that have two toes pointing forward and two pointing backward. Young sapsuckers learn to make sapwells by watching their parents.

Sapwells attract insects, birds such as warblers and hummingbirds, and animals such as squirrels. You may have heard the tale of the discovery of maple syrup by Native Americans who noticed a squirrel licking sap dripping from wounds on trees. Who knows, maybe a yellow-bellied sapsucker was involved? There’s also a legend about a sapsucker getting drunk on fermenting birch sap.

Yellow-bellied sapsuckers occasionally come to feeders, usually for suet. Their calls may sound like the “mew” of a cat. Both males and females drum during the mating season. To hear yellow-bellied sapsucker calls and drumming, check https://allaboutbirds.org/guide/Yellow-bellied_Sapsucker/sounds.

Fortunately, yellow-bellied sapsuckers have been increasing in number since the 1960s. This is good news at a time when many other bird populations have declined over the same period. One reason for sapsuckers’ success may be the growth of young forests on former agricultural lands over the past 60 years.

Keep an eye out for sapwells and yellow-bellied sapsuckers in the spring months. Many yellow-bellied sapsuckers will be passing through (April-May) as they migrate toward breeding grounds in the land of birch and maples in northern New England and Canada. Watch again in fall as they journey to wintering grounds in the southern U.S., Mexico, and Central America.