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White birch with old sapsucker holes

The Unique Behaviours of the Yellow-bellied Sapsucker

Have you ever noticed rows of shallow holes in the bark of a tree in your neighbourhood? If so, there’s a good chance they were created by a Yellow-bellied Sapsucker! As their name suggests, these woodpeckers largely rely on sap as their main food source. Just like humans who tap birch or maple trees in the spring, sapsuckers use their long beak to drill narrow, circular wells into the tree’s xylem, which gives them access to the sweet sugary sap moving up from the roots to the leaves in the early spring. The birds will wipe up or suck the oozing sap with their brush-like tongues. After the tree has leafed out, sapsuckers begin making shallower holes in the phloem of the tree instead, which must be regularly maintained to keep the sap flowing throughout the summer. They will return again and again to the same tree and also consume the insects attracted to the sap. As old holes heal over, they will just keep moving up the tree and creating another row of fresh sap wells. It is not just sapsuckers who enjoy these sap wells. Studies have shown that hummingbirds often nest near sap wells and may even time their migration to coincide with that of sapsuckers. These sap wells provide an important food supply for these tiny hummingbirds when they migrate north before the flowers have bloomed.

Male Yellow-bellied Sapsucker

The Yellow-bellied Sapsucker is one of the few migratory woodpecker species. After overwintering in the southern United States, Mexico, and Central America, sapsuckers migrate to the boreal forest each spring and being arriving on their breeding grounds in May. Interestingly, females tend to migrate further south than males.  Once they’ve arrived, they quickly get to work establishing a territory and finding a mate, which the males accomplish through rhythmic drumming on dead hollow trees in the forest. However, sapsuckers have also been known to use man-made materials to help them in their territorial drumming – don’t be surprised to hear them making a racket while drumming on metal chimneys, drain pipes or even street signs! While some people think that they are just crazy, they are just trying to sound like the biggest toughest sapsucker in the neighborhood.

While this is a quiet week for our banders as they enjoy some time off after a busy spring, this break won’t last long as the Fall Migration Monitoring Program starts up in mid-July. Our songbirds will begin migrating soon, so get out there and enjoy them.

by Laura Brandon, Boreal Educator