Saturday, June 26, 2010

Seasonal Essay for July

July
One of the delights of childhood on a July evening is catching fireflies (lightning beetles) and placing them temporarily in a jar to watch their amazing tiny flashlights. The intermittent luminescence serves to bring males and females together. There are several species in our area and the rate of flashing varies among them so that only members of the same species will mate. Lightning beetles are beetles (not flies), a group containing at least 300,000 described and named species, roughly a third of all insects. The British biologist, J.B.S. Haldane, was asked by a cleric, "As a biologist, what have you learned about the nature of God?" Haldane replied, "He is inordinately fond of beetles."

Many years ago in New Guinea, a friend and I were collecting biological specimens when in the near distance we saw an intermittent glow. We initially thought that some other crazy biologist was roaming the woods, but when we reached the source it was a tree covered with many hundreds of lightning beetles and they were flashing in unison! It made biological sense. Whereas the light from a single beetle flashing in the dense forest wouldn't carry far, the bright light from many could draw mates from a much larger distance. Synchronous behavior occurs in other animals too. The scattered individual voices of spring peepers (tiny tree frogs) often settle down into synchronous calling.

The organ which produces the light in a lightning beetle is modified muscle, just as is the electric organ of electric eels. The light is efficiently produced, roughly 90% of the energy that goes into the reaction comes out as light. In an incandescent light bulb, the best we can do is 15%, the rest being lost as heat. Fluorescent bulbs are still only about 20% efficient in converting electricity to light, but in comparison with incandescents, for the amount of electricity they do convert, they get much more light.

The next time you push a light switch, think orf those many creatures who come equipped with their own built-in lights.

Wednesday, June 2, 2010

Seasonal Essay for June

June
The singing of birds reaches its height in June. Even though, for the most part, we find bird song to be beautiful, it is not designed for our pleasure. Just as with those flowers we call beautiful, but which evolved not for us, but because their bright colors attract pollinating insects, so also with bird song which serves to attract mates and identify territory. But we can listen and gain great pleasure, and the singing, once we have learned a song, serves to identify the bird that makes it even when we don't see it. Three walks in the Skidmore woods a few years ago produced a total of 55 different kinds of birds, some seen, some heard, and some both seen and heard. Among them were the brightly colored Indigo Bunting, Scarlet Tanager and Baltimore Oriole and eight different Wood-Warblers. Others, like the Wood Peewee, the Red-eyed Vireo, and the Oven Bird might well have been missed had I not heard their songs.
Bird watching has become a national pastime which is fortunate for anyone newly attracted to this rewarding recreation because there are many good published guides to bird identification and recordings of their songs. Our geographic area is so attractive that with climate change, even some more southern birds over the last few decades have come to call it home: Cardinal, Carolina Wren, Tufted Titmouse, and Red-bellied Woodpecker.