Because of this species' abundance, Native Americans in California and perhaps elsewhere used the Acorn Woodpecker for food and even developed specialized traps to catch birds as they emerged from their roost holes. Feathers were used for ornamentation on garments: one existing full-size cape is completely covered with red crown feathers from what may have been several thousand individual birds.
More recently, the primary threats to this species are from habitat loss and degradation. In the southwestern United States and parts of Mexico, much of the montane riparian and pine–oak habitat where this woodpecker occurs has been damaged by overgrazing, which has probably lead to substantial population declines in many areas (158). Poor regeneration of oaks in California is likely to have a major effect on this species in the future, but there is no indication of population declines at this time; on the contrary, the population at Hastings Reservation has significantly increased over the past several decades apparently due largely to canopy regrowth of existing trees (Hagemeyer et al. submitted). In all areas, conversion of oak, encinal, pine–oak, and riparian forests to other uses causes substantial loss of habitat. Additional threats include competition for nest holes from introduced European Starlings (see Behavior: Agonistic Behavior), destruction of oak and pine granaries for firewood or development, the occasional legal and illegal shooting of birds to prevent depredation of nut and fruit crops and damage to structures, and loss of oak habitat due to climate change. As for the latter, studies based on climate modeling suggest that the distributions of valley oak (Quercus lobata) and blue oak (Q. douglasii), two of the most common oak species in California, could shrink by 54–59% within the next century due to climate change (169) and be subject to regional extinctions (170).