What do you do when you’re done with hibernation and your thick winter coat is too heavy for the coming seasons? These bears dancing in the forest have an answer.

In this clip from Planet Earth II‘s Mountains, Sir David Attenborough explains how rubbing their backs on trees helps bears shed extra fur and make their presence known to other bears in the area.

“Some trees, it seems, are particularly suitable for rubbing. Bears have their favourites and will travel long distances to visit them… There are now around 30 bears in this one valley. As they rub, each leaves an individual and recognisable scent. So the tree soon carries a list of who’s around, which might help individuals to avoid a fight.”

And find a mate. Studies also suggest there are additional benefits beyond chemical communication.

Saps, resins, and tars stick onto bears’ fur and skin when they rubbing against tree bark. From The New York Times:

“For years, biologists have observed that brown and black bears have an affinity for certain types of trees — especially conifers. They are also attracted to beech tar, which is a useful experimental proxy for substances leaked by trees. The appeal of the tar is so strong that scientists use its sticky, strong scents to attract bears for studies or to call them inside in zoos.

“To test the hypothesis that beech tar is a tick repellent, [bear bioloigist Dr Agnieszka] Sergiel found herself staring at tube after tube of tar and trapped Dermacentor reticulatus, a widespread hard tick known to feast on bears. She watched to see if the ticks would run away from beech tar on one side and toward safe, plain water at the other end of the tube.

“And run they did!

“It was really obvious they hated the beech tar,” said Agnes Blaise, a biologist at the University of Strasbourg in France and an author of the study.”

Why are these bears dancing in the forest?

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