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Whole Lot of Holes: Yellow-bellied Sapsuckers Leave Signs of Presence

Woodpeckers are one of those types of birds we can count on seeing all year long in northern Illinois. Even in the dead of winter, we can catch glimpses of woodpeckers in our forests or at our bird feeders. This isn’t true of yellow-bellied sapsuckers, however. 

A yellow-bellied sapsucker on a tree trunk covered in sap wells.
A yellow-bellied sapsucker. (Photo via Shutterstock)

Yellow-bellied sapsuckers are the only woodpeckers in the eastern United States and Canada that are fully migratory. They have distinct breeding and winter territories. Northern Illinois is in the middle of these territories. This means we most often see these birds during their migrations. 

These woodpeckers are typically seen in northern Illinois between April and May and in September and October. While the southern half of Illinois is included in their winter territory, they are not typically seen in the northern part of the state in the winter months.

When they are seen here, don't expect bright flashes of yellow to catch your eye. The yellow on yellow-bellied sapsuckers is subtle. They aren’t bright yellow like goldfinches or yellow warblers. They are mostly black and white with red foreheads. The yellow in their name comes from a pale yellow patch on their bellies. This patch can look more whitish than yellow. 


Words to know

Distinct: Recognizably different from something of a similar type.

Excavate: To make a hole by digging.

Horizontal: Parallel to the horizon.


You can tell the difference between the males and females by their throats. Males have red throat patches, and females have white throats.

Many of our local woodpeckers are insect eaters, and yellow-bellied sapsuckers are too. However, sapsuckers rely on sap from trees for part of their diet too. To get at the sap, they drill holes into trees. These holes are easily recognized by their pattern. Sapsuckers drill neat horizontal rows of sap wells.

They start the drilling process in early spring by drilling into the inner trunk, called the xylem. This allows them to get at the sap that is moving up to the trees branches. Later in the season, they drill more shallow holes that are usually rectangular in size. They don't have to drill as deeply because the sap is in a more exterior part of the trunk called the phloem. 

Drilling sap wells takes up a lot of time for yellow-bellied sapsuckers. They have to work at the wells constantly to keep the flow of sap coming. The sap attracts insects to the trees, and the sapsuckers eat them too. They also eat the inner bark from the tree as well as seeds and fruits. Sap itself only accounts for about 20% of their diet.

Sapsuckers prefer trees with sweet sap, like maple and birch trees. However, sap wells have been seen in more than 1,000 species of trees and woody plants. They aren't frequent visitors to bird feeders, but they will sometimes feed on suet and mealworms in feeders.

All their work drilling holes into trees helps other birds as well. Ruby-throated hummingbirds and other hummingbird species as well as chickadees, nuthatches and ruby-crowned kinglets can sometimes be seen drinking the sap from these wells in the spring. The sap is useful for these birds because it is before a lot of their usual food sources are producing nectar. Bats, squirrels and insects like bees, moths and wasps can also eat the sap.

Yellow-bellied sapsuckers are forest birds. They are more particular about their habitat in the spring and summer. Because they rely on sap, in the spring and summer they prefer forests with fast-growing young trees. In the winter, they can be found in many types of deciduous forest.

Woodpeckers are known more for their drumming than their calls and sounds. Yellow-bellied sapsuckers have a unique drumming pattern. They drum more slowly than other woodpeckers, and the pattern is more irregular. They pause during their drumming sequences, starting with a long series of drumming then a pause followed by slower knocks. 

In places where they breed, yellow-bellied sapsuckers often choose to nest in the same trees where they drill their wells. The male birds excavate a cavity to be used for a nest, and the same nest can be used for many years. Females incubate the clutch of four to six eggs for up to 13 days. The hatchlings are cared for by their parents for a few weeks before fledging.


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