Christmas tree cultivation major Christmas tree growing region, Douglas-fir has always been the primary species grown. A full one-half of all trees produced in the Pacific Northwest are Douglas-fir. Douglas-firs typically take five to seven years before they are mature enough to sell as Christmas trees. Also common in the region are noble fir, a tree which commands a higher price than Douglas-fir, and grand fir, which accounts for about 10 percent of the annual harvest in the Northwest. Other species collectively account for only 3–5 percent of the total Northwest harvest. In North America, Fraser fir, grown in the Appalachian Mountains of
Medium tree finch same. This reflects the fact that the two species feed on the same type and size of insect. The beak of the medium tree finch is intermediate in size between the small tree finch and large tree finch. All three species are found in the same habitat. The medium tree finch is threatened by introduced predators such as rats, mice, cats, and the smooth-billed ani, as well as habitat loss, which has occurred through clearance for agriculture. The introduced fly "Philornis downsi" is a significant threat to the survival of this species. Parasitic larvae of this fly live in the