Summer World_ A Season of Bounty - Bernd Heinrich [9]
The twigs bearing buds that I stuck into a jar on my desk, while snowstorms raged outside and Fahrenheit temperatures dipped into the range below zero, and that then produced leaves and flowers, reminded me of summer to come. Beyond that, they reminded me of overeager runners who have prepared for a big race for over six months, and who are ready and set to wait for more and more specific cues that signal the start. The last “go” signal is a warm temperature pulse. Such pulses are sometimes reliable cues of the beginning of spring, but for the leaf buds, apparently only if they occur in late April or early May.
2
Awakening
23 April 2006. THE SUN SHINES AND THE FIRST CROCUSES are blooming around the house. In days, they will be gone for a whole year. I can’t resist trying to preserve one by sketching it in color. The flowers normally stay closed all night and open late in the morning as though they awake then. Are they responding to sunlight? Temperature? Time? I observed and experimented and think it may be all of these. The crocuses in sunshine in our yard didn’t open until 41°F. If I darkened them (by inverting a garbage can over them) they closed and stayed closed even at 50°F but opened at 70°F while they were still in the dark. However, by five-thirty in the afternoon while there is still sunshine they closed even if at 45°F. Might native flowers act similarly?
I NOTICED THE BLOODROOT FLOWERS FROM OUR WOODS raising their petals straight up at night to tightly enclose their reproductive organs. On the other hand, in the daytime in sunshine the stamens and pistils were fully exposed as the petals were spread out to the sides. However, a day later at 50°F under an overcast sky the flowers were closed all day. I dug up a plant and brought it into the house, and there it stayed open all night, at 60°F. Was flower opening therefore controlled by temperature? I put the plant into our refrigerator at two-thirty PM, and despite the dark and cold the flowers remained open for two hours, but then closed near their normal closing time, five-thirty. On a warm (60°F) night they closed. Apparently they respond much like their insect pollinators, which have activity times, but their behavior is also affected by temperature.
17 April 2007. It is snowing hard (again!), and this snowfall topped off one of the snowiest months in New England history. Snowstorms or flurries had been the norm almost every day for the last month, and the snow was piled up to the top of the back door of our cabin in Maine even before the latest snowstorm, which then dumped 3.5 more feet, making a total of ninety-five inches so far for the winter. I felt sad for the woodcocks, robins, red-winged blackbirds, grackles, juncos, sapsuckers, and flickers that had already returned on their normal schedule, which this year was at the wrong time. Flocks of juncos and robins settled onto the only bare earth available—the shoulders of plowed roads next to tall snowbanks, where there was surely no food for them. How many of these early birds will survive? It might take weeks for the snow to melt. But I was wrong.
Suddenly, “clearing skies” were predicted, and indeed the sun came and along with it a southerly wind. Temperatures soared to 50, 60, 70, and finally 80°F. Rivulets gushed and gurgled down from the hills into flooding rivers. What a difference four days can make: the difference between winter and summer. The goldfinch males that have been coming to our feeder quickly molted their drab greenish winter garb, turning bright lemon yellow in a week. The great greening will soon begin—but not before the wood frogs have had their choruses.
The long-awaited wood frogs were at least two weeks late this year, starting their chorusing