(some parts of this blog were previously published in a 2008 essay)
The full moons of the year have long lists of descriptive names that reflect the occurrence of important ecological events that affected early human cultures and societies (photo by Luz A. Villa, Wikimedia). Much has been written about the names given to these full moons by the various Native American tribes. Hal Borland ‘s book “Twelve Moons of the Year,” and Phil Konstantin’s web site “Indian Moons” list these moon names and relate them to both the various tribes’ appreciation of the environmental changes going on around them and also the tasks they faced related to their survival.
The full moon of March (which this year occurred back on March 16) has many names. The Algonquins called it the “catching fish” moon, while the Omaha and the Cree called it the “little frog” or just the “frog” moon (we will have to wait a few weeks more, though, before the frog choruses begin to grace our evenings!). The Kiowa called it the “bud” moon, and several other tribes referred to it as the “crow” moon after the increased vocal activity of the flocks of crows as they sorted out their social and reproductive hierarchies after the long and stressful winter. And finally, a number of the more northern tribes called it either the “crust” moon after the icy snow crusts that formed due to the daytime thawing and nighttime re-freezing of the surface of the persisting snow pack, or the “sap” moon after the rising sap of the trees (especially the sugar maples!) which, interestingly, is triggered by the same daytime warming and nighttime freezing cycles that cause the snow crusts.
The name that is most frequently applied to the full moon of March, though, and which has been attributed to various, but never specifically named, Native American sources, is the “worm” moon.
We had out first, warm, wet morning of the year just a couple of days ago. On almost every sidewalk, driveway, or parking lot there were a significant number of “earthworms” of various species wiggling along on the wet surfaces, moving in apparently random directions out from their former burrows in the surrounding grass. Why are so many worms emerging all at once? It’s probably a behavioral response to moisture and temperature variables that helps to disperse and expand the boundaries of an earthworm population (no, they are not drowning in the wet soil!)
The arrival of the large, migratory flocks of robins is often coincident with this worm emergence event (although this year the robins arrived before the worms had risen!). Watching the foraging robins voraciously eating worms really gives you a good idea of how many earthworms are actually slithering along on or just hiding beneath the soil surface. Many bird species (including the grackles that I described in a previous posting) also opportunistically and with less time and effort investment than the robins, catch and consume earthworms. European starlings, an alien invasive bird species, have even been known to follow the hunting robins at a distance and then, on seeing them grab a worm, dive at them noisily so that the worm is dropped when the startled robin flies away. The starlings, then, get a stolen, protein-rich, meal. This is only one of the ecologically disrupting things that starlings do, but that’s a topic for another essay.
As many of you know, I studied earthworms very intensively in my Ph.D. research and in a variety of studies here at Penn State back in the 1980’s and early 1990’s. So, a “worm” moon should have some special meaning to me, and, I admit, it does. But, it is not at all clear to me how Native Americans had any ecological or historical connection to these worm species since almost all of the organisms we call “earthworms” are, like the European starling and the gypsy moth and Colt’s foot and so many other species of plants and animals, organisms that have been introduced to North America by European settlers as they spread across the forests and plains of the continent.
Earthworms improve the stability of a soil’s structure and its drainage properties, and they also accelerate rates of leaf litter decomposition and nutrient cycling (don’t get me started on this!). Aristotle called them “the intestines of the Earth,” and Charles Darwin spent many years of his life intensively observing and describing their activities and their extremely positive influences upon soil fertility. My own research described the immense benefits that robust populations of earthworms could have on leaf litter decomposition in established forests and field ecosystems, on re-forested strip mines, and in the cycling and rehabilitation of sewage sludge. A few years ago, though, an article in the Science section of the New York Times described some of the more negative consequences of the extremely active shredding and burying of leaf litter in worm rich soil ecosystems. The loss of leaf litter habitats for a wide variety of other invertebrates, the loss of the protective, soil covering leaf litter “blanket”, the change in the nature and energetics of the leaf litter decomposition webs, and the changes in the way that organic materials are distributed through the soil profile were all attributable to the activities of these alien species. The soils of what seem to be undisturbed ecosystems were, in fact, irrevocably changed from their original conformations by the actions of the introduced earthworms.
An earthworm as exotic, invasive species is a concept that will take me a bit of time to get used to.
So, how could Native Americans describe the mass emergence of earthworms in the spring and relate it to the March moon if these earthworm species didn’t arrive in North America until possibly the Seventeenth or even the Eighteenth Centuries? I don’t think that they could or did. And, careful examination of Konstantin’s encyclopedic lists of specific tribal moon names backs up this idea. No specific tribal designation for the March moon includes the “worm” moon. Fish, frogs, buds, crusts, crows and more are listed, but no worms. My feeling is that the “worm” moon is, like the worms themselves, an imported thing brought by the settlers from their European homes that quickly became incorporated into the structure and perceived history and ecology of their new environment.
Did the increasing abundance of the earthworms cause the American robin populations to massively increase in number? Did the earthworm activity change forest soil properties to then favor other tree species? Did the cleared land that was then plowed into farm fields become more productive because of the swelling numbers of earthworms? Did the earthworms cause the extinction of some litter dwelling beetles and other insects? Did the competitive pressures exerted by these extremely active earthworms drive native annelid species into their very restricted present day distributions?
What interesting ideas! I will need many more years of observing and experimenting to even begin to figure even some of them out!
Happy worm moon, everybody!
April’s full moon, by the way, will occur on April 15. This moon is the “grass” moon according to the tribes of the “Sioux,” the “leaf” moon of the Kiowa, and the “flower” moon of the Cherokee. It sounds beautiful, indeed. I am ready for April with its green grass, green leaves, and its lineup of so many flowers.
I had other things to talk about: the red maple buds are starting to swell and the activity of the birds at my feeders is changing. I haven’t yet seen the killdeer up on campus or the towhee in my yard or field. They are coming soon, though.