Douglas fir Douglas-fir forest is the primary habitat of the red tree vole ("Arborimus longicaudus") and the spotted owl ("Strix occidentalis"). Home range requirements for breeding pairs of spotted owls are at least 400 ha () of old growth. Red tree voles may also be found in immature forests if Douglas-fir is a significant component. The red vole nests almost exclusively in the foliage of the trees, typically above the ground, and its diet consists chiefly of Douglas-fir needles. A parasitic plant sometimes utilizing "P. menziesii" is Douglas-fir dwarf mistletoe ("Arceuthobium douglasii"). The leaves are also used by the woolly conifer aphid
WAVL tree red–black tree, because they would in effect cause the recoloring of large subtrees of the red–black tree rather than making color changes only on a single path in the tree. This allows WAVL trees to perform fewer tree rotations per deletion, in the worst case, than red-black trees. WAVL tree In computer science, a WAVL tree or weak AVL tree is a self-balancing binary search tree. WAVL trees are named after AVL trees, another type of balanced search tree, and are closely related both to AVL trees and red–black trees, which all fall into a common framework of rank balanced