grizzlies and brown bears can climb fairly easily big bears tend to not climb as much i would guess because of their shear size and curve of the claws but smaller adult griz or brown bears can climb easily and do. a friend has a picture from kodiak of a brown bear going up a cottonwood tree to extract 2x4's , limbs and 2 deer from about 20' up. they lost 10 of 12 deer they shot to the bears.