I pluck handsfulls of minute land snail shells from the surface of the water, and others from the lawn or snow. This winter the accounts of flooding from west coast storms that we heard from family and on the homeschool e-mail list suggested to us that if we were in British Columbia now we would be out, as soon as flooding subsided, driving highways to pick up drifted land snails at each culvert, and have an instant survey of the fauna of as much of the Province as we could reach. This kind of sampling summarizes the snails found along the streams, many of which are hard or impossible to find alive. It has worked well in Ontario, and it should be equally effective anywhere in Canada. If anybody wants to learn about a whole class of animals that most People never notice, and likely make a real contribution to knowledge of their local fauna, they can be on the lookout for concentrations of drifted snails as flood waters recede, and collect samples.
Snails are more abundant near limestome, and in more arid climates.
On 6 September 1996, in Ottawa, as I work upstream along the Rideau River from Carleton Univeristy, first-year Zebra Mussels cover the bottom like asphalt on a parkinglot. Below the lawnparks around the Heron Road bridge a storm sewer outfall pokes out over boulders, and shells are drifted around the eddy that must have swirled here in the storm that flooded Ottawa streets and basements on 8 August. Drift is also lodged where it was filtered from the main flow of the river by beaten-down grass at the rapids above the bridge. Much of it is tiny juvenile shells of Zebra Mussels, that wouldn't have been here in any numbers a year ago, but there is also mixture of land and aquatic snails. Such concentrations are often found above or below bridges or culverts on ditches, brooks, creeks, and small rivers.