Has spring sprung already?
From signs I’ve seen recently, spring seems nigh, but with global warming, the phenology (timing of lifecycle events) of native wildlife and plants has become less predictable, so is spring on its way?.
Here in Virginia, we often have at least one sustained warm spell by mid-February, and that was true this year. On Feb. 16, when the skies looked stormy and the temperature soared to 73 degrees, a friend and I — with my dog, Mollie, in tow — took a walk down Bean Hollow Rd., near Flint Hill. We were hoping to spot mourning cloaks or other early-emerging butterflies. We had no luck with the butterflies but thoroughly enjoyed the weather and the lovely scenery along the road.
After the walk, Mollie and
I drove to Flint Hill. As we approached the village, I heard the chorusing of spring peepers in a nearby wetland — one of my favorite signs of spring since I was a kid. As a kid, the minute I heard that sound, I headed out to look for these tiny anurans.
Later, on my way back to my home in Old Hollow, I rolled the windows down to listen for peepers but heard nothing. That didn’t surprise me. With increased shade and higher elevation in the hollow than where I’d heard the peepers near Flint Hill, the weather is usually colder here and spring animal and plant activity lag behind.
As I got out of my car at my house, I listened for another sound of early breeders: the calling of wood frogs. The pond in the forest above my house, on Oventop Mountain, is free of fish (which prey on frog larvae) and is the this anuran’s favorite breeding site on the property. So far, even in some warm spells, I hadn’t heard the loud clacking of the males, which arrive at the pond first, drawing the females to them with their calling. Was too much ice still covering the pond? Were the recent warm spells not long enough, or had it been too dry?
Although wood frogs have glucose in their blood that protects them from freezing and allows them to go in and out of winter torpor, they don’t usually start breeding until the water temperature at their breeding pools are warm enough for their eggs to survive. According to an article in the journal Ecology (tinyurl.com/wi-WoodFrogTemp), the water temperature must be 43-75 degrees (Fahrenheit) for at least 50 percent of wood frog eggs to survive. Once it’s warm enough, wet weather triggers what is often described as “explosive” breeding.
Mollie and I headed up to the pond, just to be sure the males hadn’t started arriving. When we crested the dam, I could see the pond was clear of ice, but I saw little animal activity — mostly just insects, such as the water striders skating on the pond’s surface. Something along the edge occasionally churned up the water, but I couldn’t make out which animal caused the disturbance. I waited a while and didn't see any frog heads pop up.
The temperature continued to swing up and down last week, but by Tuesday (Feb. 20), it soared to 74 degrees at my house and we’d had a little rain. Mollie and I went back to the upper pond so she could take a swim and I could look again for wood frogs, but the frogs were still no-shows.
On the way back, I did get a
glimpse of another sign of spring — a medium-sized, orange butterfly fluttering through the forest edge. It was flying too fast and disappeared before I could identify the species, but my first thought was eastern comma, another early emerging butterfly. Like the mourning cloak, it doesn’t rely on flower nectar, which is not usually available this early, for its food. The comma mostly feeds on animal remains or scat, and the mourning cloak on tree sap.
By 3 p.m., the temperature was 77 degrees. The next day (Feb. 21), it rose to near 80. Still hearing no frogs up the mountain, I took Mollie down to the lower ponds to check for another early sign of spring — skunk cabbage, which blooms in the wetland adjacent to the one of the ponds. The flowering of this bizarre-looking plant was, indeed, well underway. The blooms, in their leafy cowl (see sidebar), were sprouting up out of the muck pretty much everywhere, despite the unusually low level of water down there. I also heard that American hazelnut is blooming, so likely other early bloomers are also getting started.
Near dusk, Mollie and I went on a drive through the hollow to listen for peepers. Hearing none there, we went on to Thornton Gap Church Road to a pond favored by the little frogs, but no sound there, either. I stopped to chat with friends up that way, and by the time I left, night was falling and storm clouds were piling up over the mountains and heading our way.
Amid thunder rumbling overhead, I drove home, planning to check the peeper pond again. I finally started hearing peeping as I approached the pond. I stopped briefly to record the calls (hear online at rappnews.com/wildideas), then continued home.
As I turned onto Old Hollow Road, the clouds cut loose with torrents of rain. Peepers appeared, hopping all over the road, on their way to their breeding pools. Soon the rain was coming down so hard that I could barely make out the road and gave up trying to dodge the peepers, hoping they weren’t getting crushed beneath my car’s wheels.
For the next ten days, temperatures are forecast to be close to the March averages for Sperryville, which are a high of 56 degrees and a low of 31. I’ll keep checking up the mountain and through the hollow for peeping and clacking, hoping to hear both soon.