SPECIES

Pinyon Jay Gymnorhinus cyanocephalus

Kristine Johnson and Russell P. Balda
Version: 2.0 — Published March 19, 2020

Breeding

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Phenology

Pair Formation

In adults, pairing occurs throughout the year, usually shortly after the death of a mate. Breeding jays that lose their mates during nesting quickly obtain new mates and breed with them the same season. Yearling birds may attempt to form pair bonds in their first spring but not breed until two years of age (2). Courtship usually starts in November (see Behavior: Sexual Behavior) but is highly variable. Some yearling females mate with older males; rarely do two yearlings mate.

Nest-Building

Breeding commences late February–early May (93, 63, 17), but may vary among neighboring flocks and varies greatly within a flock among years. In northern Arizona, nest-building was initiated in early to mid-February, when previous cone crops were heavy and late winter snowfall was moderate. When fall cone crops were light or snowfall heavy, nest-building was delayed until late March to early April.

Across New Mexico, Pinyon Jays nested from March–May or April–June (147, 148, 149, 115). The latest nest in those studies was active in mid-June (KJ). Contrary to expectations, Pinyon Jays generally nested later in southern New Mexico than in areas farther north, possibly due to poor cone crops and increased reliance on insects (KJ). Laboratory tests revealed that the presence of green cones and pinyon-pine seeds stimulates breeding. The presence of green cones can override declining photoperiod and stimulate autumnal breeding; this has been documented in one population of Pinyon Jays in New Mexico (144, 3). Abundant insects have stimulated early nesting in New Mexico (4).

Nest construction was highly synchronized within a flock. In the Flagstaff, Arizona, Town Flock, for example, all breeding pairs initiated nest building over a 5–10 d interval, with 25–35 pairs of birds observed building nests on the same day in the same colony.

First/Only Brood per Season

If weather conditions are mild, females may start laying within three days (mean 2.3 d, n = 21 nests) after completion of the nest. If extremely cold temperatures and/or snow occur after completion of the nest, egg-laying may be delayed up to 8 d. Each pair has only one successful nest per season, but pairs which fail in their first attempt may form satellite colonies and re-nest. Some pairs may re-nest 5–6 times in one season.

Nest Site

Characteristics, Selection, and Microhabitat

Details of nest-site placement were observed in two flocks in northern Arizona which nested in ponderosa pine forest. This plant community is a monoculture (e.g., of 417 nests located, 405 nests were in ponderosa pines). Lower-elevation flocks in Arizona and New Mexico are known to use pinyon pines and junipers for nest sites. Nests are placed at heights ranging from < 1 m (rarely) to 35 m. Nests may touch tree trunks or be located at the tips of branches where foliage is most dense. In northern Arizona, > 50% of nests (n = 229) were on the southern aspects (south, southwest, southeast) of trees (89, 2). Such nests receive relatively high amounts of solar radiation that can warm the female, nest, and eggs. These females can absorb 40% more solar energy than females nesting on the north sides of trees, while the cool microclimate of a shaded nest site could increase an incubating female's energy expenditure by 10% (114). Prevailing winds in late winter and early spring are from the southwest and may be strong enough to dislodge south-facing nests from the vegetation. This conflict is often resolved by placing nests on the south side of tall pine trees in a location sheltered by a nearby tree to the south of the nest. Two nests are rarely placed in a single tree (71).

Individuals appear to learn to associate nest location with the fate of that nest and make different choices for subsequent nest placement after losing a nest. For example, nests near tops of trees are often preyed upon by crows and ravens, but these nests are quick to become free of snow after spring blizzards. Lower nests are better concealed from predators but are heavily shaded and do not shed snow readily; thus they are often abandoned after heavy snows. When high, exposed nests are preyed upon, 80% of these jays moved their next nest to a concealed location lower in the tree. After their nest was destroyed by snow, birds moved their nest 25% higher into more exposed locations. Nest height shifts as birds age; older birds nest lower in trees than do younger birds and may be able to compensate with efficient foraging for nesting in cooler, more energetically demanding sites (150).

Within a colony, related birds generally place their nests farther apart than the mean distances among all nests (71) such that nearest-neighbor nests are those of non-relatives. When pairs fail in their first breeding attempt, they initiate second nests in satellite colonies that may be 3–5 km from their original nest site. Relatives usually do not breed in the same satellite. As some pairs succeed, satellites gradually become smaller as the breeding season progresses (88, 89).

Nest

Construction Process

In Arizona, birds left the roost and fed for about 1.5 h, then flew as a flock to the traditional nesting grounds, where breeders commenced nest construction in midmorning. The outside platform was constructed of twigs measuring 6–40 cm in length, usually collected and transported to the site by the male. Construction of the outside platform takes from two to four days. Next, both members of the pair collected coarsely shredded grass, which was then woven into the twigs. These grasses become progressively finer and more shredded toward the innermost section of the nest. Innermost nest-linings consisted of a fine powder made from wooly plant leaves, horse hairs, rootlets, and shredded bark. The female played a progressively more active role as nest construction proceeded, solely arranging the final nest-lining.

Pairs may build for three to four hours continuously on some days or may stop after about one hour, followed by group Kawing and flight off the nesting grounds. The reason for these departures is not clear but may be for foraging. When predators are detected, nest construction stops and predators are mobbed. On especially cool, windy days, birds may cease building in mid-afternoon and feed as a flock until going to roost. Average time to build nests in northern Arizona was 7.3 d (range 5–9, n = 21).

Structure and Composition Matter

Nests examined near Flagstaff, Arizona (n = 22; 89) indicated that the nest is an open cup, fairly large and bulky, consisting of three components: (1) an outer platform of sticks, all showing signs of being at least one year old; primarily of Russian thistle (Salsola kali; 100% of nests), snake-weed (Gutierrezia sp.; 75%), gray rabbitbrush (Chrysothamnus nauseosus; 80%), tumble mustard (Sisymbrium altissimum; 60%), and horse-brush (Tetradymia canescens; 30%); (2) a midlayer of course grasses from the genera Andropogon, Bouteloua, and Poa (all common on the study area) and moderately finely shredded bark; and (3) an inner cup of fine, powdery materials (finely dissected plant parts, feathers, horsehair, cloth, rootlet, shredded bark). The mean mass of the outer stick platform was 80 g ± 5 SD; the number of sticks/platform 162 ± 14 SD, most < 1 cm in diameter. Mean mass of the nest cup lining was 67 g ± 6 SD, and it averaged 46 mm thick. This layer probably adds significantly to the insulation of the nest. Pinyon Jays are attracted to human made materials such as cotton cloth, mattress materials, and paper tissue for lining nests. After snow or rain, these materials do not dry out as rapidly as natural materials; these materials, eggs, and nestlings sometimes freeze together, causing nest desertion (71).

At most sites in New Mexico, nests in pinyon pine trees had an outer cup of pinyon pine twigs. In northwestern New Mexico, pinyon pine twigs provided structural support, but nests in Utah juniper trees (Juniperus osteosperma) had an outer cup made of strips of bark. In New Mexico, stick platforms were sometimes started but not completed (K. Johnson, unpublished data); these may be the result of courtship (see Courtship Displays: Stick Manipulation).

In northern Arizona mean outside nest dimensions were 111 mm wide and 65 mm deep (n = 43 nests; 89). Old nests are surprisingly sturdy and can remain in place for a year or more. Birds have not been seen collecting material from these nests or reusing them or the site for another nest.

Dimensions

In northern Arizona, outside nest dimensions were 111 mm wide and 65 mm deep (n = 43 nests, 89).

Microclimate

No data.

Reuse of Old Nests

Abandoned nests are surprisingly sturdy and can remain in place for >1 yr. Never has a bird been reported to collect material from these nests and reuse it or reuse it or the site for another nest.

Nonbreeding Nests

Nonbreeding nests are unknown; however, small piles of sticks which appear to be partial nests may be the result of courtship (see Behavior: Sexual Behavior: Courtship Displays: Stick Manipulation).

Eggs

Shape

Egg shape can be quite variable but is mostly short-ovate to elliptical-ovate (17).

Size

Mean measurements of 50 eggs in the U.S. National Museum were: length 29.2 mm (range 26.0–32.0); width 21.7 mm (range 20.0–23.4) (93, 17). Mean measurements of 91 eggs from 22 clutches at the Western Foundation of Vertebrate Zoology (WFVZ) were: length 29.37 mm (range 27.12–34.28); width 21.28 mm (range 20.01–22.64). Some overlap with those of Bent (17; L. Kiff, personal communication).

Mass

The average mass of eggs from Flagstaff, Arizona was 6.65 g (n = 199), approximately 6.7% of female body mass (98.9 g; 12).

Color

The ground color of eggs is bluish white to pale blue, speckled or blotched with chocolate brown to reddish-brown spots, often concentrated on the large end. The background hue, color of blotches, position of blotches, and density of blotches is female specific.

Surface Texture

The surface is “finely granulated, slightly glossy” (93).

Eggshell Thickness

No data exist on shell thickness, but Bendire commented on the relative “strength” of Pinyon Jay's eggshell (93). Empty shell mass averaged 0.393 g (range 0.332–0.445; Western Foundation for Vertebrate Zoology [WFVZ]; L. Kiff, personal communication).

Clutch Size

Clutch size is 2 (rarely) to 5 eggs. Two-egg clutches are most often abandoned (151). For a flock of Pinyon Jays near Flagstaff, Arizona, mean clutch size ranged from 3.0 to 4.32 eggs (overall mean 3.70; n = 307 clutches). Based on 115 nests containing 474 eggs (records at WFVZ from throughout species' range), mean clutch size was 4.12 eggs (range 3–5 eggs; WFVZ); no geographic variation in clutch size was noted. All eggs in a given nest are similar in color and marking patterns, and individuals appear to recognize their own eggs (2).

Egg-Laying

The female lays one egg per day. Egg-laying occurs in midmorning (even during snowstorms) after pairs have fed as a flock for about 2.5 h and returned as a unit to the breeding grounds. The female stealthily enters the nest, while the male flies up to a high, exposed perch. The male's presence is a reliable sign that egg-laying is underway. Females may spend 0.5–1.5 h at the nest laying an egg. During the laying period, a female may return to her nest periodically to sit on incomplete clutches, possibly to protect eggs from freezing temperatures, rain, and snow. Two birds were once seen sitting on a nest containing a partial clutch (RPB).

Incubation

Only the female has a brood patch and incubates. Incubation is initiated immediately after the third egg is laid, even if the clutch will eventually contain 4 or 5 eggs. Thus, eggs may hatch over a 2- or 3-d interval in a nest that contains > 3 eggs. In 3-egg nests, hatching is synchronized. Incubation, as defined by Nice (152), lasts 17 d for birds in northern Arizona (12) and New Mexico (144).

Parental Behavior

The following is from Marzluff and Balda (2). In northern Arizona, an incubating female rarely leaves her nest for more than a few minutes and is fed exclusively by her mate, on average once every 73 min (n = 210 feedings). The interval is highly variable, depending on food supply, weather, time of year, foraging expertise of male, etc. During extreme winter conditions, a male may feed his mate on average 3.8 times/d.

During early-season nesting attempts, males of incubating females forage as a flock, returning to the nesting colony as a synchronized group. They collect pine seeds from their caches, berries, and arthropods during these foraging bouts. Group foraging allows these males increased vigilance for predators, efficient food finding, increased vigilance of their seed caches, and synchrony when returning to the colony to feed females.

Upon approaching his nest, the male utters Nears or Near-ers (Sounds and Vocal Behavior: Vocalizations). This alerts the female that her mate is nearby, and she readies herself for food transfer by standing, stretching, and facing in the direction of the approaching mate. When no danger is present, the female is fed while standing on the nest cup, but if potential predators are present, she may fly from the nest to be fed. During warm afternoons, she may fly up to 400 meters to meet her approaching mate. When fed on or near the nest, female gives soft Chirrs or musical subsongs with wings quivering, but when away from the nest, she emits loud begging calls with strong wing beats. After being fed, a female may stretch, preen, and defecate before returning to the nest, or stand on the nest to roll eggs and rearrange nest material. She also rearranges nest material while sitting on the nest. Most food transfer in the colony is noisy and takes only about 45 s, after which the colony becomes silent.

Hardiness of Eggs Against Temperature Stress; Effect of Egg Neglect

Not known.

Hatching

Preliminary Events and Vocalizations

No audible sounds have been detected from eggs about to hatch.

Shell-Breaking and Emergence; Parental Assistance and Disposal of Eggshells

Hatching usually occurs in midmorning, but some afternoon hatching has been observed (RPB). The egg is first opened at the large end; no aid from parents has been observed. Parents often eat the eggshells, but a few have been carried off and wedged into crevices or needle clusters in trees. The female sits tightly once a nestling has emerged. The duration of hatching is unknown.

Young Birds

Condition at Hatching

At hatching, nestlings are pink-skinned with pterylae discernible as roughened areas with tiny transparent bristles where rectrices will later appear. No true neossoptiles are present. The yellowish-pink bill contains a whitish egg tooth at the tip of upper mandible. The culmen is ~7.5 mm in length; width across the commissural point is ~10.5 mm. Eyes are tightly closed and mouth lining is a bright salmon red. The length of tarsometatarus is ~11 mm; toe spans ~13.1 mm (n = 26). In northern Arizona, the average body mass of young was 6.26 g (range 4.0–8.6). Nestlings are capable of producing soft peeps (12).

Growth and Development

Nestlings hatch at 6.1% of the adult mass, and mass increases logistically 3–14 d after hatching. By day 10, young birds attained 53.8% of adult weight (12). During the second half of the nestling period, mass increase was greatly reduced as feather growth was most pronounced. Based on Ricklefs' regression equation for correlating growth rate and body size (153), Pinyon Jays have an expected time interval of 13.3 d to grow from 10 to 90% of asymptotic weight. Northern Arizona birds had an observed value of 13.4. At 27 days of age (6 days postfledging), and the ratio between their mass and that of adults was 0.787. This low value may reflect foraging patterns, as birds with a low adult-to-fledgling ratio are commonly ground feeders (153). By fledging, at 21–22 d, they are at 76% of adult mass, a slower rate than for many passerines (12).

Rapid growth of primaries occurs from 8–25 d; rectrices grow fastest at 12–40 d (see Table 2), and skin color gradually shifts from pink to dark purplish blue. By 8 d after hatch, eyelids open. Eyes are a dull blue-gray, and the egg tooth is evident as a white tubercle. Also on day 8, dorsal body feathers, primaries, secondaries, and coverts are small pins; rectrices are tiny white brushes; tarsometatarsus measures ~29 mm, and mouth-lining is bright orange-red. At day 15, nestlings are dorsally well feathered, but the undersides of wings and abdominal region are largely bare. The culmen is grayish to purple, except for the proximal third of the lower mandible and the region of commissural points, which are yellowish. At day 22, the culmen color is yellowish horn basally, with a tiny white remnant of the egg tooth, and tarsometatarsi are adult size at ~42 mm (12).

At day 8, a shadow over the nest stimulates nestlings to stretch upward, flap wings, and emit loud squeaks. By day 15, a shadow over the nest causes nestlings to crouch deeply into the nest, and nestlings have been observed preening. Between days 16 and 22, nestlings sometimes hop out of the nest onto supporting branches then back into the nest; wing-flapping is common. Birds preen themselves and nestmates. Before fledging, young birds often sit on the rim of the nest and support branches. Nestlings fledge at 21–22 d.

Control of Body Temperature

Individual nestlings initiate thermoregulation by shivering at about 5 days of age. At about day 12, they can maintain high, constant body temperatures, despite low ambient temperatures. The number of brood mates determines the timing of effective nestling thermoregulation. Broods of 2 young begin regulating body temperature when 10 days of age, but broods of 3 young can do so at 8 days of age (154). Thus, females with smaller broods must invest more time and energy in brooding than females with larger broods. During harsh weather, pairs with two nestlings are more likely to abandon their nests than pairs with larger broods (151).

Parental Care

Brooding

No data.

Feeding

In northern Arizona, food samples (80 items from 24 young in 6 nests over a 15-d period) were collected by collaring nestlings with pipe cleaners to prevent them swallowing food. These nestlings were fed various arthropods and pine seeds recovered from seed caches made months earlier. The most important arthropods in the diet of nestlings in northern Arizona were grasshoppers (Orthoptera, 37%), spiders (Arachnida, 16%), butterflies (Lepidoptera, 15%), beetles (Coleoptera, 12%), flies (Diptera, 4%), and true bugs (Hemiptera, 2%). Pine seeds made up 11% of the diet (89). In New Mexico, key arthropods were grasshoppers (33%), butterflies (21%), beetles (7%), and spiders (4%); pine seeds made up 32% of the diet (4). New Mexico nestlings may have been fed a higher proportion of two-needled pinyon (Pinus edulis) seeds because this pine is denser on the New Mexico site. Both studies reported one eastern fence lizard (Sceloporus undulatus) in the sample, and Ligon (4) reported gravel fed with some regularity. The nestling diet is unknown over most of the species' range.

Pinyon Jays are mainly terrestrial foragers; 5 of the 6 most prevalent classes of food found in the samples above are essentially restricted to ground and herbaceous strata during the early spring months. These include acridid grasshoppers, gryllids, pinyon seeds, carabids, and larval noctuids. The diet was diverse, containing 35 major taxa, only four of which were not arthropods. Due to low temperatures and periodic snowfall, arthropods were extremely inconspicuous during this time; hence, the diversity of foods fed nestlings indicates the foraging skill of the parents.

Methods of Feeding

Because the female broods almost continuously for the first 10 days, the male forages for himself, his female, and the nestlings. After 10 days, the female may accompany her mate, leaving nestlings unattended, especially on warm afternoons and later in the nesting season. Parents carry food in an expandable esophagus; thus, large amounts of food can be delivered to the young per feeding visit. Parents regurgitate food to the young, with strong lateral shaking motions of the head followed by extension of the neck to force food out of the adult's mouth. Foods fed to young in this manner are covered with a clear, mucilaginous secretion (12).

Rate of Feeding

The following information is from 800 h of observations at 36 nests of the Town Flock in Flagstaff, Arizona (2). On average, parents made 1 visit to the nest every 46 min, an extremely low rate for a terrestrial passerine. Visits are made by a single parent 48% of the time. In a typical hour of observation, parents fed young for an average of only 54.8 s. The male and female divide nesting duties, with the male doing the majority of the feeding (< 70%) and female performing more of the cleaning (< 60%). Because of this division of labor, a single parent is not able to raise a brood of young (RPB).

Parental care is influenced by the date of nest initiation, number of nestlings, and age of nestlings. At early-season nests, parents spend more time feeding and less time cleaning than at nests later in the season. At later nests, parents increase the number of visits to the nest but provide less food per visit. Fewer visits early in the season when temperatures are lower may minimize rewarming the young, whereas more cleaning later may reflect the increased activity of blood-sucking fly larvae or other parasites. In large broods, females increased their feeding of nestlings and males increased their contribution to cleaning. Parents spent less time per visit at nests with large broods than with small broods (2).

Nest Sanitation

Nests are exceptionally clean. After feeding a nestling, the parent gently touches its anal area, stimulating defecation of a mucous-encased fecal sac, which is either eaten or carried off by the parent.

Invertebrate Associates in the Nest

Nesting females are often seen clambering about the nest from top to bottom, probing inside and out, possibly in response to the presence of blood-sucking fly larvae of the family Calliphoridae. These flies overwinter in crevices and holes in trees and stumps and become active on warm winter days. They penetrate the nest to lay their eggs in the nostrils of the nestlings. Upon hatching, the fly larvae obtain their first blood meals from a nestling's nasal tissue. After a number of blood meals, larvae grow too large to remain in the nasal capsules and drop to the nest floor; there they burrow upward to attach to the bare bellies of the nestlings to obtain their blood meals, then drop back into the nest-lining. Female Pinyon Jays peck and probe with vigor removing these fly larvae and presumably eat them. Eventually the larvae drop from the nest and pupate in the soil. Their effect on the growth and development of nestlings must be substantial, but it is not studied to date.

Cooperative Breeding

Helpers

In northern Arizona, a few relatively small subordinate yearling males help their parents at the nest, especially in years when the sex ratio favors males. In a 10 yr of study, 27 helpers were identified; > 95% of these were sons from the previous year. Annual variation in frequency of helping was high. Helping behavior was most prevalent in 1977, when 48% of all nests had helpers, while fewer than 10% had helpers in most other years. Helpers were apparently concentrated in some family lineages, but not in others (155, 2). Over an 8-yr period, 13% of all yearling males were helpers. In 41 extended families followed in northern Arizona for 16 yr, helping occurred in only 9 families. Almost all helper-lineage birds had one or more of the following characteristics: born into a helper family lineage (39%), helped parents (18%), was helped as a nestling (11%), was helped as a nestling and later helped parents (5%). Helper-lineage pairs produce a preponderance of sons that did not breed in their first year and lived longer than sons from nonhelper-lineage pairs. None of the helper-family lineages followed went extinct, but over half of the 32 non-helper-family lineages did (150). Nothing is known about helping in other parts of species' range.

Activities of Helpers

Helpers do not assist with nest construction, egg-laying, incubation, brooding, or feeding the female. They seldom approach the nest until eggs hatch. Then they participate in all parental duties, including feeding nestlings, nest sanitation, and nest-guarding. Helpers may visit the nest alone or in the company of one or both parents. At 4 nests with 4 nestlings each, helpers accounted for 30% of feedings and 14% of nest sanitation (155, 2). Females (but not males) with helpers reduced their frequency of feeding nestlings. There is no indication that helpers bring inappropriate food items to young. Helping behavior declined dramatically once nestlings fledged.

Results of Helping

For 16 pairs of birds, all with equal breeding experience, the presence of a helper did not improve breeding success or quality of the young produced. When parents had helpers, they did not show higher subsequent survivorship than when they had no helpers. Neither nestlings nor parents apparently directly benefited from “helping” (2).

Males that helped and those that did not help produced equal numbers of offspring per breeding attempt. Helping did not improve the survivorship of helpers or give them a competitive edge in obtaining quality mates. Helping may be extended family care (i.e., parental facilitation;156) provided by exceptionally productive parents to inferior sons. Thus, the experience of helping may allow subordinate sons to subsequently perform as average male jays, thus benefiting both helpers and parents (2, 125).

Brood Parasitism by Other Species

No brood parasites have been present during the initial nesting attempt of the season, but Brown-headed Cowbirds (Molothrus ater) are present during later nesting attempts. No cowbird eggs were found in Pinyon Jay nests in northern Arizona. Of 115 nest records at the Western Foundation for Vertebrate Zoology, none mentions the presence of cowbird eggs. It is possible that some conspecific nest parasitism occurs; however, in northern Arizona, where each female lays a signature egg, no unusual eggs have ever been seen in any nest.

Fledgling Stage

Departure From Nest

Young depart the nest when 21–22 d old, earlier if the nest is disturbed by a potential predator. At 15 days, young can survive out of the nest. At fledging, young are weak flyers and sit silently in the vegetation. When parents approach with food and give the Near call, young give loud Begging Chirrs. As young become more mobile, they form crèches. Upon hearing begging calls of other nestlings, they hop and fly weakly to associate with them, thus forming a multifamily crèche. Nestmates normally perch near one another in the crèche. Most parents of crèching young form a foraging flock and return as a group to feed their young. Adults with food emit soft Nears. Fledglings respond by becoming alert, looking about, stretching wings and legs, and giving soft Kaws. When a parent approaches, fledglings begin Chirring loudly, exposing their bright-red mouth-linings, and beating wings frantically. Parent-young recognition is based on vocalizations (116). Crèches are usually surrounded by 4 to 8 adults sitting silently on high exposed perches and giving Racks and Multiple Racks when approached by predators or researchers. Sleeping, exploring their environment, allopreening, and pecking at each other are common behaviors (80). Young are fed about once every 45 min and feedings take about 3.5 min to complete. In a crèche of 30–40 birds, the incessant begging can be heard from a distance of 1 km and must serve to attract predators. Begging young are sometimes fed by adults other than their parents (13% of 313 feedings; 116). These nonfilial feedings are probably not accidents; they may be intended to curtail begging calls by other young to keep the crèche as quiet as possible. Mortality in the crèche is extremely high (57%; 2) as Northern Goshawk, Cooper's Hawk, falcons (Falco spp.), and Red-tailed Hawk (Buteo jamaicensis) are common predators.

As fledglings mature and gain feathers and flight capabilities, a crèche begins to fly as a unit to foraging areas. Young gradually become nutritionally independent of their parent six to eight weeks post-fledging. Young continue to beg from their parents for about 12 wk after they leave the nest, but parents ignore them.

Development of Caching Behavior

At 2 wk post-fledging, caged young were seen to pack food into their mouths and throats after being fed, reminiscent of filling the expandable esophagus by adult birds. They also start hiding food in nooks and crevices ( 81, 80). In the wild, juveniles were first observed “play caching” at 3 wk post-fledging and “real” caching when 6 wk out of the nest. During the first 6 wk after fledgling, birds cached a preponderance of nonfood items, including a roofing nail, rabbit (Sylvilagus sp.) scat, unripened juniper berries, bark, and dead insect exoskeleton (81, 80, 99). Seeds of pinyon pine are recognized as food items immediately, but young must learn to distinguish edible and inedible seeds and to open them (95). In years with no cone crop, juveniles are inept at handling seeds at feeders (A. Dunlap, unpublished observations).

Immature Stage

After 12 weeks of age, young fly with the flock and harvest pine seeds in their first autumn. In later winter and early spring, they form into a nonbreeding yearling flock that wanders the home range while adults are breeding (88). Yearlings court during this time (RPB).

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Figure 2. Annual cycle of breeding, molt, and migration of Pinyon Jay.

Thick lines show peak activity, thin lines off-peak. See text for details.

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Pinyon Jay nest, California.

Nest is an open cup, fairly large and bulky, consisting of an outer platform of sticks, a midlayer of course grasses, and an inner cup of fine, powdery materials. Specimen: San Jacinto Mountains, Riverside County, California. 23 April 1961. Ruler is in cm.; photographer Rene Corado.

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Pinyon Jay clutch, Oregon.

The ground color of eggs is bluish white to pale blue, speckled or blotched with chocolate brown to reddish-brown spots, often concentrated on the large end. Specimen: Redmond, Deschutes County, Oregon. 10 April 1930. Ruler is in cm.; photographer Rene Corado.

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Pinyon Jay nestling.
© Troy Corman, Arizona, United States, 08 Jun 2016
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Juvenile Pinyon Jays.
© Steve and Cyndi Routledge, Oregon, United States, 13 Jun 2018
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Adult Pinyon Jay with juvenile.
© Dan Ellison, Montana, United States, 28 Jun 2019
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Adult Pinyon Jay with begging juvenile.
© Ken Chamberlain, Oregon, United States, 02 Aug 2018

Recommended Citation

Johnson, K. and R. P. Balda (2020). Pinyon Jay (Gymnorhinus cyanocephalus), version 2.0. In Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.pinjay.02