19 November 2010

Cochlicopa on the garage door—The finale

I started posting about the snails, Cochlicopa lubrica, on my garage door at the end of May (see below for links to the previous posts). The last time I checked on them was on 20 August when there were several of them stuck on the door. I thought they would take advantage of the fall rains and sooner or later descend to the ground. But then I started noticing that there wasn't much activity on the door even on rainy days.

Finally, 6 days ago I decided to investigate. There were 9 snails stuck to the garage door at various heights above the ground. Two of them, I noticed, had faded numbers next to them.

According to my notes, I numbered those snails on 13 August. So these 2 had not moved since then.

I removed all the snails and placed them in wet cups. About 8 hours later 2 had come out of their shells; the rest, shriveled up in their shells, were too far gone beyond recovery. The 2 numbered snails were among the dead.

I was puzzled initially. Why hadn't these snails climbed off the garage door to the greener pastures below where food and water were undoubtedly more abundant? Had they gotten stranded on the garage door during a dry period? But I think the explanation of these snails' demise is simpler: they were going to die anyway and they happened to be dormant on the garage door when they expired.

I am hoping a new generation will climb up the door next spring.

The previous posts:







Janetfb said...

So why do snails crawl up the side of my house and die? We have dozens who have done just that on the south side of the house during a fairly moist summer.
The Ag Extension Service thought they might be Rabdotus. I am near Austin, Texas.

Fred Schueler said...

I'd favour "gotten stranded on the garage door during a dry period" because that's my explanation for the Cepaea hortensis and Neohelix shells I find along some railway tracks in Ottawa.

The problem with testing these hypotheses is the immense number of snails you'd need to dry out and then revive at weekly intervals, in comparison to others kept alive/ in order to get any convincing data on expected active/dormant lifespans.