Habitat
BREEDING: Generally found in temperate and mountain coniferous and mixed forests and woodlands, especially pine-oak woodlands, and locally in southern lowlands; also forage in cultivated areas, suburban gardens and parks (Subtropical and Temperate zones) (AOU 1983; Braun 1994). Will often forage in diverse habitats not used for nesting.
North American Coastal populations usually found below 1,000 m in a variety of forest types, especially pine-oak, spruce, fir, Douglas-fir (PSEUDOTSUGA MENZIESII), redwood (SEQUOIA SEMPERVIRENS), cedar (THUJA spp.), hemlock (TSUGA spp.) and alder (ALNUS spp.; Braun 1994). In Oregon and Washington, typically found in Douglas-fir, hemlock, cedar, and spruce (Braun 1994). In Oregon, most abundant in western third of the Coast Range in association with distribution of Pacific red elder and cascara buckthorn (Sanders 1999). Recorded occasionally foraging above timber line on LUPINUS species (Gabrielson and Jewett 1940). In northern California, found in Douglas-fir forests, spruce groves, alder thickets and redwood snags (Glover 1953, Braun 1994). May use spruce in greater proportion to availability (Glover 1953). In southern California, typically use pine-oak (Braun 1994).
Interior populations nest in mountains, with highest densities between 1,600 and 2,700 m in areas dominated by ponderosa pine (PINUS PONDEROSA) and oak (QUERCUS spp.), but are also found in lodgepole pine (P. CONTORTA), pine-Douglas-fir forests, and spruce-Douglas-fir-fir (PICEA-PSEUDOTSUGA-ABIES; Braun 1994; Keppie and Braun 2000). In Colorado, most abundant in forests between 1,800 and 3,200 m and those dominated by ponderosa pine and Gambel oak (QUERCUS GAMBELLI); also uses spruce-fir-aspen (PICEA-PSEUDOTSUGA-POPULUS), lodgepole pine (P. CONTORTA), limber pine (P. FLEXILIS), riparian habitats and agricultural areas in foothills (Braun 1973, Andrews and Righter 1992). In Utah, uses Gambel oak and pinyon pine (P. EDULIS, P. MONOPHYLLA); in Arizona and New Mexico uses oak-juniper (QUERCUS-JUNIPERUS) and pinyon-juniper woodlands (Keppie and Braun 2000).
In the neotropics, a bird of mountainous forested country, usually in deciduous broadleaf forests, broadleaf evergreen forests and scrub (Rappole et al. 1995). In Mexico and Central America, found in highland pine-oak, pine-oak-fir, and oak woodlands, between 1000 and 3000 m during the breeding season (Stiles and Skutch 1989, Hutto 1992, Howell and Webb 1995). In Panama, uses forest, forest borders and clearings with large trees between 1200 and 3000 meters (Ridgely and Gwynne 1989). In Colombia, usually found between 2000 and 3000 meters in humid mountain forest habitats, as well as clearings with scattered large trees and steep scrubby slopes (Hilty and Brown 1986). In Venezuela, recorded in northern mountain habitats, including paramos, open fields with scattered trees, savannas, second growth, and wheat fields. Occurs between 900 and 3000 meters north of the Orinoco River, between 1200 and 3000 meters south of the Orinoco (DeSchauensee and Phelps 1978). May range seasonally to areas higher or lower than 'normal' range (Hilty and Brown 1986, Ridgely and Gwynne 1989, Stiles and Skutch 1989, Howell and Webb 1995).
Mineral springs and mineral graveling sites are important for mineral intake by adults, especially during the nesting season. Pigeons show strong fidelity to mineral sites (Jarvis and Passmore 1992). Use of mineral sites is most notable in Coastal populations, and less so in Interior populations where mineral needs may instead be satisfied by abrasion of grit that is highly basic (Braun 1994). Although several authors suggested that mineral sites provided calcium in diet (March and Sadlier 1972, Jarvis and Passmore 1992), a study in Oregon revealed sites to be low in calcium but high in sodium, where principal foods (fruits of SAMBUCUS spp. and RHAMNUS PURSHIANA) were high in calcium and low in sodium (Sanders and Jarvis 2000). Site use probably depends not only on mineral content, but also vegetation structure, development, level of human activity, and traditional use by pigeons (Sanders and Jarvis 2000).
Nest habitat (e.g., nest placement, type and age of tree or shrub, elevation and aspect) varies greatly throughout range (Braun 1994). Will nest in a tree or shrub 4-10 m from the ground, usually near the bole in dense foliage, and often next to an opening or above a slope or precipice. The nest is a loose platform of twigs (Terres 1980; Braun 1994; Baicich and Harrison 1997). Birds display strong fidelity to nest area (Braun 1972, Schroeder and Braun 1993), and nest trees may be used repeatedly with new nests constructed each year (Braun 1994).
NONBREEDING: Interior populations winter primarily in pine-oak woodlands and montane coniferous forests in Mexico, along the Sierra Madre Occidental; also in tropical deciduous forests in Sinaloa (Braun 1994). Coastal populations winter from central California to Baja California in pine-oak woodlands, coastal chaparral (ADENOSTOMA, ARCTOSTAPHYLOS, CEANOTHUS, and QUERCUS spp.) and adjacent agricultural areas (Jeffrey 1977).
Reproduction
Breeding season is prolonged, beginning in March in south to early May in north; breeding reported well into fall in some areas, probably in response to food availability (Gutierrez et al. 1975, Jarvis and Passmore 1992, Braun 1994, Baicich and Harrison 1997). Timing of breeding less a factor of latitude or photoperiod than of food availability (Gutierrez et al. 1975, Jarvis and Passmore 1992). Two broods per season not unusual, and three broods possible (Keppie and Braun 2000). In Colorado and New Mexico, breeds in spring and summer, sometimes in fall in New Mexico if acorns are abundant (Gutierrez et al. 1975).
Clutch size usually one (85-95%), infrequently two. Incubation by both sexes, about 18-20 days. Nestling altricial and downy. Young leaves nest in 25-30 days. (Terres 1980, Baicich and Harrison 1997; Keppie and Braun 2000).
Will defend nest area and there is evidence of territorial flight displays and defense (Peeters 1962, Jackman and Scott 1975), but territoriality is not well-studied (Keppie and Braun 2000). Based on second-hand reports, Neff (1947) suggested that this species is a communal nester in New Mexico, but this has not been corroborated by any other subsequent research. Braun (1994) suggested that repeated use of nest tree with a new nest constructed each year may give the appearance of communal nesting and asserts that birds of Interior populations are solitary nesters.