Saturday, February 21, 2015

Snowday sapsucker

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.

1 comment:

John Gilbert said...

Very nice pictures of the Sapsucker!