Mooning Around

E-Vo-Lu-Tion. 64. Category is: Rainy Spring.

Evolution is the name of the game. And we all play, whether to win or lose I am not so sure. We all fall down. We are all being played.

Have you read The Beak of the Finch? I read it freshman year of college (a year so long ago now that I am like all the other old people who talked to me about things that happened to them in college and I wondered what sort of unearthly world that took place in). It was a good book, required for honours Biology 2 (which was the one about zoology and evolution). I liked my professor and my TA. One day in lab we went to catch things in the stream, and the professor came too, and he praised me because I was so enthusiastic. His name was Dr. Kent and he specialized in fossils.

The Beak of the Finch is about two biologists (married to each other) who study Darwin’s Finches in the Galapagos. Darwin’s Finches, of course, look like birds of all varieties, such as the ones we know here as flycatchers, seed eaters, sapsuckers… all the many birds with their various bills grown to help them eat various things. Only these Galapagos birds are actually all descended from one bird that came to those isolated islands and had babies that grew up to fill basically all of the niches a bird can fill. There are many. All of the warblers that are flying back through Maryland right now are specialized to succeed despite the immense competition just from warblers. Some will forage for insects at the top of the tree. Some in the middle. Some in the mid-level tree branches but closer to the tips of the branches. One, the Black and White Warbler, hops up and down the trunk of the tree to find the insects in the crevices of the bark. And all of these birds are nevertheless quite similar, and eating similar things of a similar size at the same time of year in the same species of trees.

Without all the spaces already taken, the bird that landed on the islands once upon a time was free to let its children specialize in everything. The Galapagos could have a warbler-like bird of its own, only it is not closely related to them at all. It is begotten and begotten and begotten from what may or may not have actually been a finch. Now those birds on those far flung islands are all different species. But the cool thing discussed in The Beak of the Finch (discovered by those biologists) is that their evolution continues, and can be observed even over the course of one breeding season. A dry year changes the beak size of the birds that are born the next year. A wet year does the same.

Can you see where I am going with this? We have had more freaking rain this year than in any May on record. It has also been unusually cold. And? Well naturally this is the May when I have a little more time to spend outside, looking for pretty migrants and listening to and learning the songs of breeding birds. But you know what? The birds do not do much singing when it is below a certain temperature. It has been far too quiet for this time of year, and the songs are of precious short duration, lasting only from spring migration in late April through the end of the breeding season which is often over by July. Alas. I have still heard many. And as a newish birder, I have seen a lot of new things. Seeing a species for the first time is called getting a Lifer, and I am still new enough to get them all the time. I am aware though, that it will not be so easy next year. Despite the quiet, the birds are still flying through, from Central and South America to their breeding grounds, here or farther North into Vermont and Maine and Canada. And I have seen a lot of them!

But what I have been thinking and wondering about more than the birds, in all the rain, is the Luna Moths. They should have been coming out from their overwintering cocoons just as this rainy season started. Will the rain knock them down and ruin their wings before they can find a mate? Surely they are resilient. Will the rain breed more resilience next year? But then, if the Luna Moth numbers are declining (they are) will there be enough of them to benefit from a newfound resilience? Or will more areas just be wiped out, more places where Luna Moths used to be but are no more? I don’t know, and I can’t even guess what all the variables might be.

Last year, while desperately collecting Sweet Gum leaves for my own Very Hungry Caterpillars, I found two Luna Moth eggs on one Sweet Gum leaf. Although already overwhelmed with caterpillars and in need of no more, I put them in a Pyrex container to wait out their hatching. It never came. Normally it takes less than two weeks for an egg to hatch, but after four weeks they still sat still. Then one day I noticed a hole, just like the holes the caterpillars leave in their eggs when they emerge. I panicked, thinking I would see a shriveled up dead caterpillar that had starved. Instead I found a tiny wasp flying around. The eggs had been parasitized, by what I assume was a tachinid species. Some are native, I understand, but the one known for attacking Luna Moths was brought here from somewhere else to combat Gypsy Moths. Heavens, I think Gypsy Moths were all grown ups talked about some summers of my 1980s childhood. Anyway, the Gypsy Moths died back, but the Tachinids decided to stay. They are believed to be the reason that many species of Giant Silkmoths are completely gone in much of New England. I worry about what is happening here. I worry, truth be told, that this invasive species will act like invasives do and thrive in the face of difficulty. They will endure the rain easily, while the Lunas will be fewer in number and even more vulnerable to having their sweet hope-filled eggs used to create the monsters who will continue to destroy them.

But who knows? I hope I find a Luna Moth this year. I hope I find some eggs. And I hope that I will find some that contain a pretty green caterpillar that can eat its way through to the moon in a someday clear sky.

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