Nature Notes: Sense and Sensibilities
What motivates us, what motivates nature? The DNA and the enzymes and hormones it provides the blueprints for are a driving force, of course, but then, too, there are the stimuli, of which there are many different kinds varying in strength depending upon our ability to sense them. Our senses receive these stimuli and cause us to do this or that, think this or that. There isn’t a single organism, one-celled or multicelled, including the members of the plant kingdom, that doesn’t receive and respond to stimuli. One doesn’t have to have a nervous system to react to stimuli. Even the simplest of life forms — viruses, viroids, and those proteinoids that cause mad cow disease exhibit cause and effect behaviors that govern their actions inside their hosts.
The modern human is said to have free will, he or she is able to react differentially to stimuli by virtue of thought. I have an hour to spare. Do I want to watch “American Idol” tonight or would I rather read Newsday? On the other hand, most philosophers and psychologists don’t attribute free will to other life forms, so-called infrahumans and certainly not to plants, which lack nervous systems. In these organisms the automatic response to certain stimuli can make or break a wild population. Yes, the passenger pigeon that once flourished over half of America but became extinct in the first years of the 20th century was heavily shot for food, but its downfall was ultimately tied to the weather (and possibly disease), it migrated each spring according to the usual climate cues, but in the late 1800s got decimated by unscheduled spring storms on the way north.
Temperature, day length, gravity, photoperiod, ultraviolet light, sound, atmospheric pressure, wind, moisture, scent, and tastiness are just some of the many stimuli that drive nature and, for that matter, many of us humans, when we are running on automatic and not according to ratiocination. In some organisms, such as in birds, photoperiod is dominant and migration is timed to it; but it is also affected by temperature. Birds return north earlier or later each spring depending upon the temperature. This spring they are arriving earlier, as much as two weeks earlier. Among them was a yellow warbler that Vicki Bustamante heard singing and then spotted near Big Fresh Pond on Friday.
The flowering and leafing of higher plants and the parasitic insects that hatch out to take advantage of it are governed by a combination of daylight and temperature and the amount of daylight, so-called temperature-light days. Because it has been a warm winter and, thus far, a warm spring, forsythias, andromedas, daffodils, dandelions, and a host of other plants are all blooming much earlier than usual. If we are hit by a severe cold snap, there could be hell to pay. Plants would suffer and their pollinators would suffer.
But the flip side would be fewer leaf and flower-eating insects in the next generation. Fortunately, in most cases, the conservative nature of the genomes of organisms saves them from the occasional catastrophe and eventual extinction. And most plants have backup systems. They can lose their flowers or leaves in a freeze or storm, and reflower or releaf once it turns warm again.
It is mind-boggling how members of single species and its conservative genetic code can exhibit the same exact behavior over a wide area without intercommunication. For example, the forsythias on the North and South Forks of Long Island flowered practically on the same day. The Eurasian earthworm Lumbricius terrestris, described by Linnaeus more than 250 years ago, comes out of the ground after a long winter for the first time come spring on the same day, whether it resides in Southampton, East Hampton, or Shelter Island. One sees the little mounds a half-inch high and an inch in diameter composed of semi-digested dirt balls scattered side by side over a wide area as also was observable on that same Friday. But soil moisture, not only temperature, governs the emergence of earthworms, so their emergences here and there are somewhat staggered according to the level of soil moisture. Rain brings them up all at once and that is why they are called “rain worms” in most of Europe.
One such remarkable emergence of a burrowing insect was observed on Friday in several widely separated locations in the hamlet of North Sea in Southampton Town on Friday. It was a new experience for me, as I’m better versed in plants, birds, fishes, reptiles, and amphibians than insects. While Vicki and I were scouring the countryside for emergent plants and new avian arrivals, we came upon a most curious situation — hundreds of tiny holes in sandy open spots no bigger around than a Ticonderoga pencil. Around each hole was a small volcano cone of fresh yellowish sandy soil that sharply contrasted with the bleached-white soil separating each mound.
We paused awhile and looked a bit more closely, and a brownish bee-like organism came out of one of the holes, while another buzzed around our heads.
As far as the eye could see, in several different spots there was nothing but bare ground with hundreds of little yellow domes, a burrow in the center of each. Vicki took a few close-up photos and sent them to Daniel Gilrein, the entomologist at the Cornell Cooperative Extension center in Riverhead. It’s most likely the burrowing bee, Colletes inequalis, was his reply. Dan had been receiving a lot of reports of the same holes (and their inhabitants) from several different eastern Long Island spots. Interestingly, these bees furnish their burrows with maple tree pollen. It makes sense, in the areas we saw them in great numbers, there were lots of red maples in flower.
In my 60-plus years of observing nature on eastern Long Island, I had never seen anything like it. What caused them to open their burrows? Was it the odor from the early flowering maples? I believe so.