The Morse Code tapping of Yellow-bellied Sapsuckers has just started reverberating in northern New England woodlands once again – a sure sign of spring. There is an interesting relationship between sapsuckers and hummingbirds, with hummingbirds reaping most of the benefits. It is thought that the Ruby-throated Hummingbird may time its migration north to coincide with that of the Yellow-bellied Sapsucker in some areas. In northern New England, hummingbirds arrive on their breeding grounds about a month after sapsuckers, insuring that sapsucker-drilled sap wells will be waiting for them. The reason this is important is that these wells are an important source of nutrients (both sap and insects attracted to it) for hummingbirds as well as sapsuckers. In addition, and not surprisingly, hummingbirds often place their nest near sap wells. This affinity for sap continues well past the nesting season – – hummingbirds have been observed following sapsuckers throughout summer days. (Photo: male Yellow-bellied Sapsucker & male Ruby-throated Hummingbird)
Yellow-bellied Sapsuckers have returned and in between sending their Morse code messages, are drilling into over 1,000 species of woody plants to obtain sap. At this time of year, sap wells are drilled into xylem tissues (transport water and nutrients from roots to branches) to feed on sap that is moving upward; after deciduous species leaf out, sap wells tap phloem tissues (transport sugars and other nutrients made in the leaves to other parts of the tree). Unlike sap drawn from the xylem which contains from 2-3% sugar, phloem sap may contain 20-30% sugar.
Sapsucker tongues have a fringe of hair-like projections along the edges which enable the sapsucker to lap up the sap that accumulates in a well (“saplapper” would be a more accurate name for these woodpeckers). Recently a female sapsucker landed on the trunk of a nearby Sugar Maple and tapped eight wells. She then spent the better part of the afternoon inserting her brush-like tongue into the wells and drinking the sap that collected. The entire time she was drinking sap, she was constantly (8 times per hour) evacuating a stream of clear liquid (as opposed to the typical uric acid excreted by birds). Apparently much of what goes in must come out.
Yellow-bellied sapsuckers are just starting to arrive on their northern breeding grounds. As you might assume from their name, these birds feed on the sap of trees. Their horizontal lines of drilled holes are a familiar sight, especially in trees such as paper birch, yellow birch, sugar maple, red maple and hickory, all of which have a high concentration of sugar in their sap.
In addition to sap, yellow-bellied sapsuckers also eats insects (primarily ants), and spiders, probing underneath bark to find them. They’ve even been observed “hawking”– taking off from a branch and scooping up insects in the air.
Lesser known is the fact that sapsuckers also consume vegetation, including the inner bark and cambium layers of trees, the buds of trembling aspen, and a variety of fruits and seeds. The recent cold snap had the pictured male yellow-bellied sapsucker scarfing down crab apples before the sun set. (The next NC post will be on 4/11/15.)
Some of the most prolific flowering shrubs in the Northeast are dogwoods. In the spring, their flowers attract attention and at this time of year their colorful fruit stands out. There are many species of dogwood, two of which are Red-osier Dogwood (Cornus sericea) and Silky Dogwood (Cornus amomum). These two shrubs can be hard to tell apart, as they both have white flowers, red stems and similar foliage. In the fall, however, the color of their fruit differs, as does their pith, or central stem tissue. The mature berries of Red-osier Dogwood are dull white and its pith is also white. Silky Dogwood’s blue berries have white blotches, and its stem and branches have a salmon-colored pith.
The fruit of these dogwoods and others is an extremely important source of food for many migrating songbirds, as well as resident birds. Wood ducks, Northern Cardinals, Eastern Bluebirds, Gray Catbirds, Purple Finches, Evening Grosbeaks, American Robins, Yellow-bellied Sapsuckers, Wood and Hermit Thrushes, Red-eyed and Warbling Vireos, Cedar Waxwings and Downy Woodpeckers all consume dogwood berries.