Cincinnati has neither the snow-removal infrastructure nor
the cold tolerance of more northerly cities. Moderate snowfall that would be
met with a shrug in Grand Rapids paralyzes this city. As a result, I had two
snow days from work last week. But, I can’t complain—I used that time to bird.
(Don’t even ask me how many hours I wasted poking my head into the bellies of
Red Cedars looking for Saw-whet Owls.)
On Wednesday morning, I stumbled across a Yellow-bellied
Sapsucker working a sugar maple. It looked miserable, as it should
have—temperatures were barely breaking the positives. No sap would weep from
its wells today.
Sapsuckers are a hot topic at the nature center this time of
year. We regale the visiting children with the importance of the quasi-mythical
woodpecker called a sapsucker. We showcase old wells and explain that
other species will steal from the sapsucker’s property. However, I was taken
aback when my supervisor referred to sapsuckers as a keystone species. Really?
I wondered. I bet if all the sapsuckers disappeared from these woods,
business would be unchanged…
Fact: other species plunder sapsucker wells. I’ve caught
Yellow-rumped Warblers in the act. But, I would contend that, at least in the
sapsucker’s winter range*, other species don’t glean a significant percentage
of their daily caloric intake from sapsucker wells**. And, here in Cincinnati, I don’t think winter sapsuckers are
abundant enough to support significant populations of, say, Ruby-crowned
Kinglets…
I realized that my hang-up might be semantic. I launched an
archaeological dig to unearth my biology textbook, which I have admittedly used
more often as a dumbbell than a vehicle of scholarship. Page 1073 defines a
keystone species as an organism that “has a much greater impact on the
distribution and abundance of the surrounding species than its abundance and
total biomass would suggest.”
Huh. Vague.
A brief search on Google Scholar confirmed my suspicions—I
found multiple articles questioning the usefulness of the term, including one
that read, “The term keystone species is poorly defined and broadly
applied.” Yup. The concept is real—as George Orwell would say, “All animals are
equal, but some animals are more equal than others.” But, labeling
Yellow-bellied Sapsuckers and apex predators like wolves with the same title
seems ludicrous. I will have to tinker with my sapsucker spiel before the next
school group comes to learn about maple syrup.
*I got thinking about sapsucker range and had to look it up.
Basically, there’s a flip-flop around the tension zone in Wisconsin and
mid-Michigan. Cincinnati is well within their winter range, but they don’t seem
abundant here.
Summer (Jun-Jul)
Winter (Dec-Feb)
**Of course, there are exceptions. See Dorian Anderson's blog for an intriguing example.
