Wild side: Regenworm Day for Robins

Tuesday, February 25th, may not be pretty warm enough to survive for a really nice day. But it was definitely a day that had the right idea. Temperatures flirted with 50 ° over the vineyard flirted by a rapid influx from mild air from the south and almost uninterrupted sunlight. After a few weeks, which were averaged on the cold side, the moderating temperature was a mighty, pleasant development. I arrived home from work to find a small herd of American Robins that fed Yard in our Oak Bluffs. That alone was not surprising; Robins Winter regularly on Martha's vineyard and so far they have been particularly abundant this winter. What impressed me about this Robins when I saw them was the prey they took: earthworms, definitely earthworms, hesitated as well as reluctant rubber bands from the floor from the birds, and swallowed with obvious relish.

In short, the mild air was a player for both the birds and the worms, which thaws the upper a few centimeters in a moist but soft consistency. The worms after the score moved to the surface, without a doubt the warmth and the possibility of sowing up with the increased availability of oxygen. And the Robins I expected were waiting for this phenomenon to use the advantages.

However, it was not just the selection of prey that seemed new. Our Robins behaved differently in various, subtle ways. Feeding was faster than I had seen it recently, and there was more arguments among the birds when dominant people chased subordinate subordinates from Prime Hunting Spots. Our amiable local herd of this kind had started very abruptly to develop into a more relaxed, less friendly connection with competing people. These birds, still migrants, will not breed here and will eventually continue to the north (perhaps a long, long way; these forest species breed north to the edge of where trees occur). But they had hormonal changes that push the beginning of breeding behavior and in the subsequent waves of Robin, which are undergoing, these changes will grow more and more clearly until members of a local breeding population finally use their claims.

The abrupt changes in the late winter are real, not illusions or wishful thinking of humans, and three main factors are aimed at the process. From its lowest pass on the winter solstice, the sun follows a path that is steadily higher over the course of winter. The sun rays reach us from a higher angle above the horizon and become steadily stronger because their path through the atmosphere becomes shorter. Less warmth and light are absorbed by the air and particles that contain it and get more at ground level.

In the meantime, the higher sunny angle also means longer days. The sun shines over the sky at a steady pace, about 15 ° per hour, so that its path grows longer from the horizon to horizon, the sun shines on us for longer every day. Sunlight, that is, not only becomes stronger in late winter, but it also becomes more abundant, and the warming effects of intensity and duration multiply each other.

Finally, the change rate at the length of the day accelerates to a maximum of the Equinox. Do not ask me to explain; Spherical trigonometry is involved! However, if we approach the spring equipment, every day is about three minutes longer than the previous one. That may not sound like a lot, but over a week it adds up to 20 minutes of additional daylight. Between all these synergist effects of the calendar, it is no wonder that the natural world reacts. Birds grow Randy; Plants become green again; Reconuate insects again to get the maturation process.

As a naturalist, I regret that our society has decided to celebrate seasonal changes. Our holidays are largely reminiscent of people or events (whether historical or religious), and we deviated from the pagan preference to celebrate moments of bending in the seasonal cycle.

The seasonal change is of course continuous. But the pace of change is not uniform. Certain moments represent turning points in which a change that is insignificant in itself exceeds a threshold and triggers sudden, penetrating changes. This year, February 25th, such a moment seemed to be such a moment – we call it “earthworm day”, the first day warm enough to bring worms to the surface so that Robins can feed. The whole world changed for the eye of a naturalist.

Spring comes reliably every year, although in a few years it takes its own sweet time to arrive. And to be sure that more winter could be ahead of us; March and even the first half of April can produce deep cold or amazing snowfall on the vineyard. But at some point the overall trend changes the direction and the extension process becomes unstoppable.

Despite its complete predictability, which is largely powered by the unchangeable earth orbit around the sun, every spring is unique. And despite my familiarity with the process – this spring will be 66.