Sumac Warehouses

(This column was first published in the February 7, 2000 Buffalo News.)

    Among the easiest to identify of our native trees in winter is the staghorn sumac. Often found in disturbed areas along highways or railroads, the species appears at this time of year as a thicket of 10-15 feet high leafless vertical branches topped with red candles. Up close those candles turn out to be clusters of hairy reddish berries gathered into ten inch upright cones.

    The name staghorn is well chosen. Individual branches do look like deer horns and this species differs from smooth sumac by the velvety surface of its upper branches. This quality is similar to that of newly grown deer horns before their fuzz is worn off.

    A sumac grouping is comprised of clones growing from a common root. Just as deer are aged by counting their antler divisions, you can tell the age in years of an individual stem by the number of its branchings. You can use this technique to determine the mother stem.

    For many years I have checked sumac clusters for birds because of an experience I had when I lived near Binghamton. A group of a dozen pine grosbeaks, one of our rarest visitors from the far north, spent several weeks that winter feeding in a single sumac grove south of the city. The birds were so tame that we could approach to within a few feet to take pictures.

    Unfortunately that encounter has never been repeated. Almost a hundred bird species have been recorded feeding on sumac, among them grouse and turkeys, bluebirds, hermit thrushes and robins, cardinals, crows and starlings. But sumac fruit serves these species only as a last resort -- like spinach to a starving child -- and it is a rare winter that drives birds to these trees. This winter on the Niagara Frontier, for example, the wild fruit crop is excellent so you won't find many birds resorting to these berries.

    Something else about sumac was discovered by Syracuse teacher Kathy Schwab's fourth-graders several years ago. Her students wrote to naturalist Ben Burtt: "Our class has been studying plants found in a field near our school. One of the plants that we studied was the staghorn sumac. When we dissected the red seed clusters, we found something we didn't expect."

    They went on to tell Burtt that they found kernels of corn, sunflower seeds and some unusual three-sided seeds in the candles and they wondered if he knew where they came from. "Could some kind of bird be responsible?" they asked.

    Unfamiliar with this kind of sumac warehousing, Burtt checked with specialists at the Syracuse College of Forestry and he posted the students' inquiry on the internet. No one had had the students' experience. But Burtt investigated sumac himself and found similar seeds. (The students' "unusual" seeds turned out to be beechnuts.)

    Burtt quickly ruled out mice, chipmunks and squirrels. Although they do cache food, he decided that "it would hardly be worth the climb" for them to store and retrieve it. A literature search indicated that, of regional birds, jays, nuthatches, titmice and chickadees commonly hoard food. His report on this episode continues: "From the large size of the beechnuts, I tend to rule out chickadees, titmice and nuthatches. The blue jay seems the most likely candidate." But he adds, "So far, I have found no one who has seen the jays actually doing this."

    I join Burtt in saluting these students. Their investigation contributed both to their own understanding and to that of the scientific community.

    But the story remains incomplete. Watch for birding activity in sumac groves and you too may add to our understanding of this phenomenon.-- Gerry Rising