Possibly marking out the boundary of the upcoming brown bear enclosure in the bear ravine. It extends a lot further up the wooded slope than I expected it to which is a very nice surprise.
My last visit was back at the beginning of October. I was surprised I didn't see any progress then but felt sure you and @Brum would see some signs of work commencing on your recent visit. The fact you didn't is slightly concerning.
As recently as the end of September this year the zoo mentioned it is hoped the bears will have arrived by Spring 2020, which isn't that far away.
Another worrying factor is the total lack of any mention of the new enclosure on the planning application pages on the council's website, which I thought would have been required due the fact it incorporates a huge listed Tecton.