Damage under enviromesh mystery.

I have an area under enviromesh. The area is about 6m x 3m. The enviromesh is held up by pegs driven into the ground. It's about 400mm high, and pegged down well all around, with no sign of entry.

The enviromesh covers (in order) four rows of brassicas: cauliflower, cavolo nero, cabbage and purple sprouting. A couple of the purple sprouting bit the dust when very immature (watering?), but everything else apart from one cabbage which keeled over was OK.

Now, one of my prized and healthy cavolo nero plants , about 8" tall, has snapped off, about 2 1/2" up. The slightly dried ends look as if they match, i.e. nothing has nibbled them. It's as if the stem has just been physically broken and the plant left lying there It's in the middle of the row.

There are moles about, but i can't see evidence of them under the enviromesh. Would a mole cause such damage? A rat? I don't know how. I have not watered the plants for nearly a week.

I'm at a loss. Any ideas?

 

Perhaps an overweight pigeon landed on it?

 

Maybe a Vole, they do it just for 'fun' !

 

Well, having been up there just now, I suspect it was the wind. Pictured through the enviromesh: