Tree hugging snails, why?

[StA.Squirrel]

I saw something like this when i was in Portugal a few years ago...except that the snails were on bushes and even individual grass blades and werent grouped together. It was June...so plenty warm enough..I think someone told methey were 'hibernating' from the dry season and waiting for it to get wet enough again.

[The Woodman]

That reminded to find the October 2006 Spanish image below StA.Squirrel



These snails are aestivating at the tips of this Agave and will have been there all summer. It seems unnatural that they expose themselves to the heat of the sun and possible predation for that length of time without perishing.

What also caught my attention is the way they have graded themselves in order of size. Do the larger specimens climb a leaf to find a gang of small of small snails at the end and decide to return to find a leaf with similar sized companions?

Dadzinskys find is quite noteworthy in my opinion.