Martin, I don't have the answers to your questions but I can provide a little background that may help. You live in an area that has no native earthworms (this may be true for Susannah, whose message you forwarded, as well). All of the earthworms you are seeing are non-native, some invasive. It sounds to me like you have at least three species of European Lumbricidae, and I have guesses on the species, although without specimens I'm hesitant to post those.
Temperature and moisture dictate much of what the soil fauna do. You may indeed be seeing the impact of weather on their activity, but we have little phenological data for reference. Digging deep into the soil and folding into a ball is a common way that earthworms get through the bad times, be they cold or dry. I doubt that more individuals are freezing unless you had extremely cold temperatures that would have frozen the soil beyond your usual frost depth. With warmer air temps and little snow cover I think the soil would stay warmer on average. Without that insulation layer there would likely be more variation in the upper horizons. It could be the change in moisture pattern if changes in moisture is a cue for emergence or resuming activity. Your hypotheses are good ones and worth testing. Heavy clay is not a problem for some species. Because of the arrangement of circular and longitudinal muscles they can get into small crevices and make them larger. -Bruce ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Bruce A. Snyder, PhD [email protected] Instructor; Coordinator, REU and URM Programs REU: ksu.edu/reu URM: ecogen.ksu.edu/urm.html Earthworms Across Kansas: ksu.edu/earthworm/ Personal: www-personal.k-state.edu/~basnyder/ Office: 136 Ackert Hall 785-532-2430 Mail: Kansas State University Division of Biology 116 Ackert Hall Manhattan, KS 66506-4901 "How many miles of unexplored caves are there?” On Tue, Apr 10, 2012 at 4:57 PM, Martin Meiss <[email protected]> wrote: > Several people have asked what species of earthworm are involved, and > sadly, I don't know enough about worms to be able to say. However, I > regularly see these types: > > 1. Big (6 to 10 inches) brown night crawlers, who sneak out of their > burrows and night and perform hermaphroditic sex acts when they think no > one is looking. Their tails are rather flattened and bristly and they can > hang on very tightly to the walls of their tunnels. > > 2. Small (3 to 4 inch) reddish worms with very noticeable whitish rings. > I often find these in large groups, perhaps 30 or 40 within a square-foot > patch of very moist rotting leaves or under the bark of very moist rotting > logs. > > 3. Small (3 to 4 inch) pale brown-to-pinkish worms without prominent > rings, sometimes quite abundant in topsoil and compost. This might be a > juvenile stage of the the large night crawler, but I don't thinks so > because they don't have the flattened tail and they don't seem to have > permanent burrows. > > Those are the common types, and all of them seem fewer this year. > > Occasionally, when I have been digging deep, say for a fence post, I have > found little pink earthworms all balled up and in a cavity in a nodule of > clay. The walls of the cavity seem to conform to the coils of the > balled-up body of the worm and show delicate sculpting. I have observed > this during warm weather and am very curious how a soft-bodied little worm > could dig into tough clay, and without leaving an obvious entrance tunnel. > > Martin M. Meiss > > ---------- Forwarded message ---------- > From: Martin Meiss <[email protected]> > Date: 2012/4/10 > Subject: Re: [ECOLOG-L] Where have all the earthworms gone? > To: Susannah Woodruff <[email protected]> > > > Yeah, it's a reply-all vs. repy-to-sender thing, but I'm not sure of the > exact wording because I have my gmail account set up in German. I'll post > your reply to the web. > > > Martin > > 2012/4/10 Susannah Woodruff <[email protected]> > >> no i didn't intentionally send it to just you. i should have hit reply >> all? not sure how to send to the whole list, but feel free to send my email >> to the whole list! thanks. >> >> Le Apr 10, 2012 à 2:44 PM, Martin Meiss a écrit : >> >> Hi, Susannah, >> Thanks for getting back to me with your observation. Did you >> intentionally send it only to me instead of to the whole list? I think >> other people might be interested in this conversation. >> >> Martin >> >> 2012/4/10 Susannah Woodruff <[email protected]> >> >>> Funny you should say that. i was just planting some peas and carrots and >>> lettuce and saw ONE worm. i thought it a bit strange too, but now I am >>> really going to pay more attention. I live in Jackson, WY and we had a very >>> mild winter--with very little snow (for us). Typically we still have >>> multiple feet of snow in our yard at this time of year and as I said, i >>> just planted stuff in my garden! >>> I will keep track and be back in touch. >>> Susannah Woodruff >>> >>> Le Apr 10, 2012 à 1:54 PM, Martin Meiss a écrit : >>> >>> Greetings, Ecologers, >>> >>> This year, in turning my compost and digging my garden beds in Syracuse, >>> NY, I have noticed markedly fewer earthworms than in previous years, and I >>> am wondering of others of you have observed this also. This could be one >>> of those natural, mysterious population fluctuations, but I'm wondering if >>> it has something to do with the unusually warm winter. Here are some >>> possibilities that have occurred to me: >>> >>> 1. The warmth might have favored some enemy (predator, disease, or >>> parasite) of the worms, letting them kill off a large percentage of the >>> population. >>> >>> 2. The lack of snow cover might have allowed such cold as there was to >>> affect the worms more strongly (i.e., allowed more heat to escape the >>> ground, resulting in lower soil temperatures) >>> >>> 3. Maybe it's not a question of temperature so much as the number of >>> times >>> the soil freezes and thaws, which might have a deleterious effect. I >>> don't >>> know whether there were significantly more or fewer than usual freeze/thaw >>> events this winter in this area. >>> >>> I have not noticed any difference in abundance of other largish soil >>> animals, like isopods, slugs, millipedes, beetle grubs, etc. >>> >>> >>> Martin M. Meiss >>> >>> >> >>
