MOVING ON FROM PURPLE POKEWEED TO SWEET, SHINY SUGARBERRY
(PLUS A WORD ABOUT PINE WARBLERS)

We noted in a past photo essay that a prolific purple Pokeweed patch popped up this past summer around Hilton Pond Center, the purple-stemmed plant producing plentiful purplish fruits that prodded a peripatetic Cedar Waxwing population into a propensity to poop purple. For a couple of weeks in early November, waxwings periodically popped into the Pokeweed, pausing to purloin purple berries and periodically pass the seeds amid a plethora of purple droppings.

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Alas, all good things in nature must sooner or later come to an end, and by late November there were no more purple berries to attract the waxwings to our American Pokeweed, Phytolacca americana. Many of its fruits were consumed by waxwings (or other local species including Northern Mockingbirds), but some dropped to earth uneaten, perhaps to germinate next spring. Once-green pokeweed leaves--bitten by frost--are now shriveled and dark (above), dangling from formerly purple stems turned a deep golden brown.

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With their nutritious Pokeweed berries gone, what was our local waxwing flock to eat? These crested birds don't come to feeders, so our seed offerings were moot. Furthermore, American Robins had already stripped crimson fruit from our Flowering Dogwoods, and our local Eastern Red Cedars this year produced few of those tiny blue berries with which Cedar Waxwings are nominally associated. But guess what? The ravenous waxwings had one more treat awaiting them high in the canopy above Hilton Pond: Bite-sized, sweet-tasting fruit from Sugarberry trees (above).

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From our office window in the Center's old farmhouse we could see silhouetted against the sky the thin branches of several tall Sugarberries from which hung a cornucopia of quarter- to half-inch shiny reddish fruits that give the tree its name. And an appropriate epithet it is, since its sugar-laden berries (above) are so sweet they were used by Native Americans who beat the fruit to a pulp and then mixed it with animal fat, rolled it into balls, and roasted it in the fire. The resulting balls had a long shelf life and became nutritious food reserves. (Quote from the "Gardening Know How" web site.) Some folks say the taste is similar to that of dates.

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Historical distribution of Northern Hackberry (above left)
and Sugarberry

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Distribution maps above courtesy USDA

We thought for a long time all these berry-yielding trees at the Center were Northern Hackberry, Celtis occidentalis, a species closely related to Sugarberry, C. laevigata. Both trees have warty bark (Sugarberry, below left) and make similar-looking fruit, but the historical distribution of C. occidentalis is to far north (see maps above). That said, both species sometimes can be found outside their natural range, planted by enthusiasts who wanted to attract winter birds to their yards.

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After careful examination of foliage on the trees at Hilton Pond, we determined we indeed had the more southerly Sugarberry (sometimes called Southern Hackberry), whose serrated leaves (above right) tend to be smooth-edged at the base. In fact, some Sugarberry trees bear leaves with few or no serrations at all. (NOTE: Although they are congeners, there doesn't seem to be any good evidence Sugarberries and Northern Hackberries hybridize or that there are intergrades where their ranges overlap, so leaf serrations seem to be a reliable identifier. In addition, mature Hackberry leaves have a sandpapery dorsal surface, while Sugarberry's are smooth.)

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These days as we look out toward Hilton Pond we can see a half-dozen towering Sugarberries; as might be expected from berry-producing trees--quite a few of their offspring have sprouted on the ground nearby. Such reproductive success pleases us--the trees also shade our office space from the bright sun of summer--but we suspect Eastern Bluebirds (above), Yellow-bellied Sapsuckers, Red-bellied Woodpeckers, and Cedar Waxwings find the trees even more important as they gobble up early winter Sugarberries against a clear blue sky.

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Incidentally, there's a non-bird group of organisms that are also attracted to either species of Celtis: The Lepidopterans. Yes, gravid female butterflies seek out both Hackberry and Sugarberry as host trees on which to lay eggs. After these hatch, hungry larvae get to work on the trees' foliage before metamorphosing into adults with names like Hackberry Emperor (above and below), Tawny Emperor, American Snout, Question Mark, and Mourning Cloak. We've seen caterpillars (and adults) of all five butterfly species at Hilton Pond, which may explain how by summer's end there are almost no undamaged Sugarberry leaves; nearly all show signs of being nibbled on by hungry butterfly larvae.

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POSTSCRIPT: After posting this installment about Sugarberry, we got an interesting e-mail from Bryan England, a long-time reader of This Week at Hilton Pond. Here's what Bryan said:

"Just wanted to say your “Sugarberry” in Installment #791 may not be a “Sugarberry," exactly, and not a “Northern Hackberry” either. What it looks like is Small’s Hackberry, Celtis smallii, which some botanists treat as a separate species, and some treat as a variety of Sugarberry—Celtis laevigata var. smallii, and some just include within Sugarberry. It is most common in the Piedmont, between the coastal and southern range of Sugarberry, Celtis laevigata var. laevigata, and the more northerly mountain range of Celtis occidentalis. Your specimen is between them in appearance, too: The leaves have more teeth than "normal" southern Sugarberry but fewer than "normal" Northern Hackberry. Small's Hackberry is not a rare tree in the Piedmont, but its in-between features have made it confusing for botanists for a long time.

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MORE YELLOW-ISH WARBLERS

We wrote a few weeks ago about how different in appearance are the two races of Palm Warbler (PAWA). Although both subspecies have bright yellow undertail coverts, the Western Palm Warbler (below left) is relatively drab while Yellow Palm Warblers (below right) lives up to their name. Representatives of either race breed far to the north across most of Canada and occur in the Carolina Piedmont primarily during migration.

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A few PAWA may overwinter here, but come cold weather Palm Warblers are far more common along the Carolina Coast southward to Florida and the Caribbean. (NOTE: We were pleased to hear from several readers who were confused by considerable plumage variation in the two Palm Warbler races and were glad to learn about the differences in that photo essay.)

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Due to considerable color variations, Palm Warblers can indeed be confusing, but there's another highly variable warbler that breeds across the eastern U.S. and winters from North Carolina southward to Florida and the Gulf Coast. We speak here of Pine Warblers (PIWA) whose plumage varies from drab (above) to eye-popping yellow (below). Although this parulid often surprises observers by showing up at suet feeders, we don't doubt hungry PIWA visit the Center's Sugarberry hoard to compete with Cedar Waxwings and other avian species for that nutritious treetop fruit.

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If their plumage varies considerably, how can one be sure at any time of year whether one is looking at a Pine Warbler? It's actually pretty easy if you take into account ALL the bird's field marks, as follows:

First, as shown in the two images above there is a pale line through the eye, resulting an a partially broken eye ring. Note also a lighter spot in front of the eye and a rather stout bi-colored bill in which the upper mandible is darker.

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Next, look for a pair of prominent wingbars , as shown on this week's immature female PIWA (above) and by a just-captured adult male (below). Wingbars are present regardless of the overall color of body plumage. (Wingbars, by the way, are the tips of covert feathers that overlap bases of the next row of feathers, providing streamlining. The bottom wingbar in the photo below is incomplete because at least one of those white-tipped covert feathers is missing.)

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The final field mark to look for in a Pine Warbler is tail spots, in which the outer two rectrices on either side are adorned with white. These long pale markings are not always visible in lateral or top view, but they certainly show when the bird fans its tail, as below.

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So that's our primer on identifying a not-so-confusing winter warbler appearing at your suet feeder. If it's got a pale line through the eye, broken eye ring, bi-colored bill, white double wingbars, and white tail spots it's almost certainly a PIWA, regardless of how drab or bright yellow it might be. Although the palest birds are likely young females and the brightest older males, they're all Pine Warblers just the same. Some will depart Hilton Pond Center and fly back north come spring, but many will stay. Almost anywhere in the Carolinas with pine lands or mixed pine-hardwoods will host breeding Pine Warblers, from the Blue Ridge Province to the vast Coastal Plain.

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HILTON POND SUNSETS
(from our on-going series)

"Never trust a person too lazy to get up for sunrise
or too busy to watch the sunset." --BHjr

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Sunset over Hilton Pond, 13 November 2022

Leaves are gone from the big Shagbark Hickory.
It's almost winter.

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Sunset over Hilton Pond, 21 November 2022

Rain clouds parted just in time for this lavender tableau.
Rootless Duckweed on the pond is dying from the cold,
allowing a much better reflection.

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Don't forget to scroll down for lists of Hilton Pond supporters and of all birds banded and recaptured during the period.

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