who put that there?

Hoodies probably.

On second thoughts, given that this is the Tweed (big river) and the tree is HUGE, it was more likely to have been the aliens from yesterday's blip that did it. Apologies for any offence caused to hoodies, who are mostly just misunderstood kids, but that's because they mumble and don't take their hands out of their pockets and stand up straight when they talk to you and what's this about sticking your hands down the front of your joggers for goodness sake, can't they wait till they get home??