From a slow moving vehicle we can see constellations of shells on the grey crushed limestone of the road shoulders, and where the off-road habitat was similar among spreading Junipers. We walk slowly back and forth on both sides of the road, scanning the littered shells for an hour and a quarter, finding each cluster somehow defective in composition, or with not enough fresh, shells which show the brown stripe. I was amazed that Fred's patience matched my own in this endeavour, as the afternoon sun dropped toward the horizon and my painting time became seriously shortened. We finally came upon this naturally pleasing arrangement of empty shells (where the live snails are is anyone's guess...) on the east side of the road and I settle down on a cushion to paint it as I see it, with no rearranging of shells at all.
We first learned of Xerolenta obvia (then Helicella obvia) when Wayne Grimm and Glen Wiggins published an account of a colony in Bethany, Ontario. In the 1990s we made some efforts to map the limits of this colony along roads and railways around Bethany.
This fall, we learned from the Canadian Food Inspection Agency (for whom we produced the book on introduced land snails and slugs in Canada) that the species had been found along Breezy Heights Road, near Antrim, and afternoon we headed out from Ottawa, so that I could see this spectacle, and we could map some of the limits of this colony.
Fred has set himself the task of seeing how extensive the colony is in the quarry, and as soon as I am settled to paint, he was over the roadside berm and into the quarry, first crossing a gravel flat where the Xerolenta shells were present in greater abundance than anywhere on the roadside, and then down steps of bedrock to the lowest level of the quarry and out onto tongues of "over burden" (soil and stumps) that had been bulldozed into the surrounding Cedar forests. Here there were few or no Xerolenta, and he found that the shells thinned out or disappeared when ever he got off the open quarry and into forest or solidly vegetated sod. So the snails inhabit the entire 600m quarry, back to its SW border at the forest -- especially where the vegetation is scattered Knapweed plants. In November Fred and Robert had found shells along 1.4 km of Breezy Heights Road, so the SW margin remains to be determined in the trailer park to the northwest, and the residences to the southeast of the quarry.
It's along roads that the open habitat the Xerolenta use is artificially created, and there's no telling how they'll stread along the eastern Ontario Road network.