The next two weeks (late April into May) will produce the peak of spring migration. Some of the migrants will pass through on their way to more northerly, even Arctic, breeding grounds and others will nest here. A few species like Red-headed Woodpeckers and Blue Grosbeaks overshoot their intended breeding grounds and generally backtrack to where they should be.
Avian migration is largely driven by food availability. Leaf-gleaning insectivores like warblers and vireos don’t arrive back in Maine until the leaves of deciduous trees are out. Swallows and flycatchers need to delay until insects are on the wing. Birds with broader diets like Red-winged Blackbirds and Common Grackles have an easier time of it, arriving en masse in Maine in March.
Then, we have the hardy birds that scoff at the rigors of a Maine winter and grace us with their presence all year long. Most of our woodpeckers fall into this category of resident birds. Hairy Woodpeckers and Downy Woodpeckers are common at feeders and in woodlands. Pileated Woodpeckers are fairly common birds, seen less frequently than one would expect based on their crow-size bodies and raucous vocalizations. Red-bellied Woodpeckers have been increasing in Maine over the past two decades and are now regularly seen. Our two three-toed woodpeckers, the Black-backed Woodpecker and the American Three-toed Woodpecker, are infrequently encountered.
All six of these woodpeckers make a living by extracting insect larvae from their galleries or tunnels in wood. The powerful bill excavates a hole to gain access to the gallery and then their long harpoon-like tongue explores the gallery until resistance is fine. A quick poke and it’s time for lunch. Perhaps you are aware of the amazing length of the tongue of a woodpecker. It is so long that it extends behind and then across the top of the skull in a sheath just beneath the skin. A woodpecker tongue can be three times the length of the bill.
In addition to this sextet of residents, we have two other woodpeckers in Maine that are migratory. Each relies on food that is only available during the warmer months.
The first is the Northern Flicker. These large woodpeckers sometimes excavate wood in search of insect larvae. However, they prefer to feed on the ground, having a particular taste for ants. A flicker’s tongue is modified as an efficient ant-harvesting tool. It is shaped less like a harpoon and more like a brush. The many tips of the tongue effectively allow a flicker to easily harvest ants. You may see a flicker pounding on the ground. The bird is excavating an ant colony with a particular goal of getting access to the soft, nutritious ant larvae underneath the soil surface. Beetles make up an important part of their diet as well.
We do see Northern Flickers lingering late into the winter or even overwintering in Maine. Flickers are quite adaptable and can make ends meet by feeding on seeds and berries.
To our south, Northern Flickers may be resident birds. In Maine, the snow prevents flickers from their favored means of ground foraging in the winter.
Our other migratory woodpecker is the Yellow-bellied Sapsucker. The name is amusing enough and its way of making a living is fascinating. These woodpeckers maintain elaborate systems of sap wells in trees. A sapsucker creates these shallow holes and then feeds on the sap that exudes from the wells. The sap attracts insects and sapsuckers will prey on these insects as well, particularly when feeding young. The protein-rich insects are just the ticket for growing nestlings.
A sapsucker visits its wells daily, enlarging them as necessary to insure the continued flow of sap. Ruby-throated Hummingbirds take advantage of these wells. Hummingbirds frequently nest near sap wells and follow a sapsuckers as it works its trap line of sap wells.
Flickers and sapsuckers, it’s good to have you back for a while.