A male yellow-bellied sapsucker at his feeding tree. Photo: Morgan Quimby/Audubon Photography Awards
By Kevin McKeon, Maine Master Naturalist
One thing we sometimes see during our spring trail walks is a butterfly that actually overwinters as an adult butterfly, the mourning cloak, which shelters in crevices it finds under tree bark, logs, in brush piles, and even cracks in buildings. Other butterflies, like the eastern comma, show up before flowers’ nectars are made, or even before the flowers bloom. Hummingbirds are now seen at some of our sugar and water feeders, happy to find sweet nourishment after a grueling migration from Mexico and Central America, arriving before many plants produce their nectar. Many other birds are still returning from their migratory winter homes; some of these are flycatchers, which eat mostly flying insects.
What are the sources of food for these early migratory arrivals and the critters awakening from overwintering? Well, there’s another early spring arrival from southern United States and Central America that helps these critters get by during early spring’s food-scarce times — the yellow-bellied sapsucker.
Keen trail walkers will often notice that the bark of some trees is pockmarked with neatly spaced lines of small holes, often in several parallel rows. These marks are the work of our yellow-bellied sapsucker, a robin-sized, black and white, red-crowned woodpecker with a red throat on the male and a white throat on the female. All woodpeckers are keystone species, having substantial and essential positive effects on their ecosystems’ biodiversity and health. There’s arguably no other woodpecker that more exemplifies that term than this colorful guy. They join our human maple sap collectors as another of nature’s creatures enjoying the sweet gift of tree sap.
Upon arrival in the spring from their wintering grounds in southeastern United States, Central America, and as far south as Panama and the West Indies, yellow-bellied sapsuckers seek out hardwood and mixed softwood forests in Canada and northeast areas of U.S. for their nesting and breeding grounds. Some rare individuals have been known to remain in these northern areas when sufficient food sources are available. They are especially attracted to populations of aspen, poplar, and birch trees for building their nesting cavities — a new one each year, sometimes in the same tree — from six to 60 feet above ground.
While awaiting their insect food sources to become more prevalent, yellow-bellied sapsuckers form small sap-oozing holes — sap wells — in sweet-sapped trees like aspen, birch, and maple. These sap wells remain open for a while and provide their early spring nourishment; as they begin to heal and dry up, the birds will re-open them, create new ones, or both. Also attracted to these wells are the butterflies, moths, and many other insects that our sapsucker needs for feeding its chicks. Sap wells also attract many other birds that gather bugs for their young. Hummingbirds are known to claim certain sap welled trees as their own, fiercely defending against other hummers. Birds of all species visit these springtime forest oases, gleaning the ants, wasps, flies, and butterflies attracted to the sap. Birds of prey take advantage of these target-rich areas too, grabbing the unfortunate bird, squirrel, or bat that are also feeding at the sap wells.
So, these sap wells are quite a critter-rich feeding ground, supporting a multitude of animals in the landscape. Healthy trees are rarely damaged to the point of death, but smaller, weaker trees are sometimes less fortunate. And as the season progresses, and sap flow slows, holes are enlarged and deepened to continually produce sap. Too many sap wells, too close together, could result in a girdling issue for a smaller tree whereby the flow of sap is insufficient to properly feed the tree, effectively starving it. This is obviously unfortunate for the tree, but in nature’s scheme of things, it’s a valuable addition to the landscape, by the creation of valuable snags — dead, standing trees — that support four times more biological life than a live tree. But some fruit orchardists consider these birds pests, and because the Federal Migratory Bird Treaty Act protects yellow-bellied sapsuckers — along with almost all native bird species — from anthropogenic harm, these farmers may need to protect their most valuable trees with wrappings to discourage sapsucker visits.
After the monogamous pair excavate their tree cavity, four to seven white eggs are cared for by both parents, and hatch about 12 days later. Butterflies, moths, and dragonflies are primary food for the chicks, along with sap and small pieces of cambium wood. After about a month, the chicks leave the nest but are still cared for, becoming independent after another two weeks. Yellow-bellied sapsuckers, despite their name, can be quite bold and will aggressively defend their territories; they’re also frequent visitors to backyard suet feeders. And, again despite the name, sapsuckers don’t suck sap but rather lick it up with their bushy tongues. Raccoons and snakes are primary predators of sapsucker nests; window collisions and domestic cats are other great threats.
They were originally considered a single species, but DNA testing in the late 1980s differentiated yellow-bellied sapsuckers into four separate species: red-naped, red-breasted, and Williamson’s sapsuckers are the western species; yellow-bellied sapsuckers are found here in the East. They’re all native to and breed only in North America. And believe it or not, a group of sapsuckers is called a slurp!
The post Sapsucker: Friend to Other Critters, Foe to Small Trees appeared first on Sanford Springvale News.
