Puzzle

After the weekly shop, where it seemed 1 in 30 was not wearing a face covering, I spent a lot of time in the garden. The bindweed is back and as I ventured behind the raspberry canes I saw, secured to the inner lip of the compost bin, what looked like a nest. The bin is open to the sky.

At first sight I wondered if it was a wasps’ bike. But I did not see anything coming in or out. Nor did I see any bees. And the length of some of the strands seems a bit much for a flying insect.

A mouse? A rat? But why at the top of the bin? And it does not look robust enough.

A bird? But any entrance must be small and very awkward to access.

So a puzzle. Any ideas?