Good Natured in St. Charles: Sapsuckers’ precision drilling a boon to other creatures

Ten years ago, I purchased a small shelving unit built by a local craftsman. Made of oak, and heavy as the packledickens, it would be perfect for displaying my collection of vintage tobacco tins – I just knew it!

The only thing was, I’d have to install it myself. Sure, in retrospect, I could have hired a handyman. But, I was fairly confident I could drill a couple holes that would match up with the hangers on the back and also hit the studs behind the drywall. How hard could it be, right?

Talk about famous last words. Four hours, countless trips up and down the stepladder, lots of spackle and a number of salty interjections later, the shelves were installed. And they looked good!

But the wall behind them? Not so much. So. Many. Holes! Even though they’re covered up, I to this day know they’re there.

If only I had the skills of a yellow-bellied sapsucker.

These birds, who happen to be visiting right now as they make their trek northward, are masters of precision drilling. They know exactly where to bore and when, thus ensuring they’ll have plentiful sap to lap (not suck, as they have no lips). Even better, the distinctive sapwells they create are nearly uniform, level and parallel.

I’m more than a little envious.

Walking through Delnor Woods Park the other day, I noticed a number of trees with lines of holes from years past. They were long since sealed (not spackled, but rather healed with the tree’s own cells), yet still clearly visible, a testament to the sapsuckers’ determined drilling.

Those marks, however, told another story, too.

By tapping holes in trees in springtime, when the sap is rising, these birds help ensure that many other creatures also gain access to the sweet elixir.

In our area, the false honey ant, Prenolepis imparis, is one of several insects known to take advantage of the sap bounty. Also called the winter ant, it forages early in the year. This tolerance for cold helps them avoid competition with other ants, a major boon for this timid species.

If ants aren’t your thing (as they aren’t, I’ve learned, for many of you), consider that the sapsucker’s drilling also nourishes a number of local lepidopterans – that is, butterflies and moths.

Even though the vast majority of these insects are still in some sort of winter diapause, as either an egg, caterpillar or chrysalis or cocoon, we do have a fair number of moths that emerge in late winter and early spring, as well as some butterflies that actually overwinter in their adult stage.

Of this latter group, mourning cloaks are perhaps the best known and the easiest to identify. Named after traditional mourning attire, these butterflies catch your eye with their overall dark appearance. Their deep brown wings have a slight reddish cast offset by a row of small blue dots just inside a pale yellow border. A woodland species, they can be found fluttering about on sunny days when winds are calm.

Red admirals also start showing up at this time of year, as do commas and question marks – the butterflies, not the punctuations, that is. These two members of the genus Polygonia are similarly orange in appearance, with irregular edges on their wings. The comma, however, is smaller, with three black spots in a row on the top of the forewings, while the question mark is slightly larger with another bit of punctuation – an elongated dash next to the three spots on its forewings. And those namesake marks? They’re small and whitish silver, and can be observed on the underside of the hindwings when the wings are folded over the back – when you look really, really close.

As if this weren’t enough traffic at the sapwells, the opportunity for free food also draws in flies and beetles, as well as mammals and birds. As you can imagine, this arrangement often turns into its own little food chain, with larger animals snacking on smaller ones, either intentionally or incidentally.

Meanwhile, the sapsuckers continue making their way north, eventually arriving in their summer territories that extend from central Wisconsin up into Canada. There, the birds continue their sap-tapping, but change their target from the sapwood or xylem layer to the inner bark, or phloem, tissue, which brings freshly created sap down from the leaves.

(Fun fact: Like using a spoonful of sugar to help the medicine go down, yellow-bellied sapsuckers have been observed dipping insects in sap before feeding them to their young. Mary Poppins would be proud!)

As you’re out and about this spring and summer, see if you can find any evidence of sapsucker activity. Maples are a favorite, but several other species can be tapped, too, including conifers.

Look for shallow holes in well-ordered rows, often right at our eye level. You might be tempted to think they’re the work of a naturalist with a drill, but they’re not. They’re much too neat for that.

• Pam Otto is the outreach ambassador for the St. Charles Park District. She can be reached at potto@stcparks.org.