Editing Douglas fir (section)

=== Use by animals ===
[[File:Pseudotsuga menziesii 01221.JPG|thumb|upright=.85|A [[snag (ecology)|snag]] provides nest cavities for birds.]]

Douglas-fir seeds are an extremely important food source for small mammals such as [[Mole (animal)|moles]], [[shrew]]s, and [[chipmunk]]s, which consume an estimated 65% of each annual seed crop. The [[Douglas squirrel]] harvests and hoards great quantities of Douglas-fir cones, and also consumes mature pollen cones, the inner bark, terminal shoots, and developing young needles.<ref name=":0" />

Mature or "old-growth" 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 {{convert|400|ha|km2 acre}} 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 {{convert|2|-|50|m|ft|round=5}} above the ground, and its diet consists chiefly of Douglas-fir needles.<ref name=":0" />

Douglas-fir needles are generally poor [[Browsing (herbivory)|browse]] for [[ungulate]]s, although in the winter when other food sources are lacking it can become important, and [[black-tailed deer]] browse new seedlings and saplings in spring and summer. The spring diet of the [[Dendragapus|blue grouse]] features Douglas-fir needles prominently.<ref name=":0" />

The leaves are also used by the [[Adelgidae|woolly conifer aphid]] ''[[Adelges cooleyi]]''; this 0.5&nbsp;mm-long [[Sap (plant)|sap]]-sucking [[insect]] is conspicuous on the undersides of the leaves by the small white "fluff spots" of protective wax that it produces. It is often present in large numbers, and can cause the foliage to turn yellowish from the damage it causes. Exceptionally, trees may be partially defoliated by it, but the damage is rarely this severe. Among [[Lepidoptera]], apart from some that feed on ''Pseudotsuga'' in general, the [[gelechiid moth]]s ''Chionodes abella'' and ''C.&nbsp;periculella'' as well as the cone scale-eating [[tortrix moth]] ''[[Cydia illutana]]'' have been recorded specifically on ''P.&nbsp;menziesii''.

The inner bark is the primary winter food for the [[North American porcupine]].<ref name=":0" />

[[Poriol]] is a flavanone, a type of flavonoid, produced by ''P. menziesii'' in reaction to infection by ''[[Poria weirii]]''.<ref>{{cite journal|author=Barton GM|year=1972|title=New C-methylflavanones from Douglas-fir|journal=Phytochemistry|volume=11|issue=1|pages=426–429|doi=10.1016/S0031-9422(00)90036-0|bibcode=1972PChem..11..426B }}</ref>