Aphelocoma ultramarinagrey-breasted jay(Also: Mexican jay)

Geographic Range

Mexican Jays range from the north in central Arizona, southwestern New Mexico and west-central Texas through the eastern central mountain chain south to Puebla, Guerrero and central Veracruz and went to Jalisco and Colima.

(Burn & Madge, 1994; Brown, 1994)


Mexican Jays are found in habitats usually containing pine (Pinus spp.), oak (Quercus spp.), and juniper (Juniperus spp.) woodland, at least in Arizona. In lower elevations they can be found in oak-lined creeks and sometimes even into grassland areas. In upper elevations, they prefer south-facing slopes with more oak trees unlike Stellar’s Jays (Cyanocitta stelleri) which prefer north-facing slopes with more coniferous trees. In Mexico, Mexican Jays occur within a wider elevational range and more pine-oak habitats. (Burn & Madge, 1994; Brown, 1994)

  • Range elevation
    1200 to 1800 m
    3937.01 to 5905.51 ft

Physical Description

As with most birds, mass varies depending on age and season, with first year males averaging 118 g in June to fourth year males that weigh in at 137 g. This change also takes place in females, with first year females averaging 122 g in June and fourth year females averaging 128 g.

Both male and female coloration is similar. Mexican Jays are greyish blue above and dirty white to ashy-grey below. Head, sides of neck and nape blue while back a brownish-grey. Lower back, rump, tail and wings blue.

Adults have a black bill while juveniles retain a pale orange lower mandible through their first year and sometimes similar spots in their second year.

(Burn & Madge, 1994; Brown, 1994)

  • Range mass
    105 to 144 g
    3.70 to 5.07 oz
  • Range wingspan
    157 to 173 mm
    6.18 to 6.81 in


The mating system of Mexican Jays seems rigid but in fact is quite flexible. In the west, these jays breed in social groups of 6 to 20 individuals, consisting of one or two breeding pairs and helpers at the nest. Helpers are offspring from previous years. In eastern populations (Texas)birds are more typically territorial. For the most part, unpaired males start to build a nest in order to attract an unpaired female in their group. When a female is near his nest site he will circle around her with his tail up. He might also call to her with the Whisper song (See Communication) while spreading his wings. Once she accepts, the male mounts the female for a brief copulation, one to five seconds. Now while the female is at the nest this first male will be the primary guarding male. Although a pair may “bond” it is not always true that a females’ young are from this first partner. Extra-pair copulations have been observed in both males and females. (Burn & Madge, 1994; Brown, 1994)

Eggs are laid in late March through April ranging from one to six eggs with four and five being most common clutch size. Second and even third clutches have been observed (although for the most part they were replacement clutches) and were smaller than first clutches. In Arizona, eggs were pale green in color but a pale blue with brown speckling in Texas. Females usually begin incubation after the third or penultimate egg has been laid. Males do not incubate. Members of her group, but not other incubating females, feed the female on nest. When she leaves the nest, for 5 to 10 % of the daytime, the nest is left unprotected. Incubation lasts 17 to 18 days. It is assumed that the young hatch on the same day because there is not a large size difference between young in a clutch. However, in larger clutches there are often runts, which shows that one or two of the eggs hatched later than the rest. Hatching has been mostly observed in the morning with the female either eating or just taking away the pieces of shell that end up in the nest. Young start out on average at 6 g at hatching and can reach 100 g in 18 to 20 days. At fledging, which occurs 24 to 28 days after hatching, young jays can actively fly for a few meters before gliding down. They might also perch nearby until group returns. At this age, their main form of locomotion is jumping, so if they get too far away or down a tree they can usually jump their way back up. (Burn & Madge, 1994; Brown, 1994)

  • Breeding season
    beginning late March to mid-April
  • Range eggs per season
    1 to 6
  • Average eggs per season
  • Average eggs per season
  • Range time to hatching
    17 to 18 days
  • Range fledging age
    24 to 28 days

All members of a breeding group participate in rearing offspring. Young are hatched without feathers and with their eyes closed. Hatchlings start out begging vertically and randomly and eventually learn to detect an approaching feeder. Most of the competition in the nest is for positioning near the visiting feeder. Young are fed mostly insects and some acorn pieces. They are fed over entire nesting period and several weeks after fledging. This dependence wanes when they start gaining foraging skills of their own. (Burn & Madge, 1994; Brown, 1994)


At the Southwestern Research Station in Portal, Arizona 2 males and 1 female reached 19 years of age and one of these males had a nest with eggs in his 21st calendar year (Brown, 1994). The period of highest mortality is during their first summer.

Humans can also affect the lives of Mexican Jays. Jays have died by eating corn kernels from a garden laced with fungicides, by finding pesticides in storage areas, and through collisions with motor vehicles. However, they are primarily preyed upon by raptors especially at feeding stations or picnic areas.

(Burn & Madge, 1994; Brown, 1994)


Mexican Jays are not migratory and often do not leave their natal group.

Communication and Perception

Food Habits

Mexican Jays mainly eat acorns (August through March), pinyon nuts (October through spring), and arthropods in the winter while in the summer they stick mostly with grasshoppers, crickets, caterpillars, other medium- and large-size insects, and lizards. Most of their foraging takes place on the ground for insects or stored food but they also search the foliage for caterpillars and acorns. They usually poke or dig through the ground litter with their bills. Foraging in groups allows for a higher success rate; sharing can occur. They do most of their insect hunting in the warmer months while in July they might visit the flowers of the Parry Agave (Agave parryi) for nectar and insects and then through December take acorns and pinyon nuts from trees.

(Burn & Madge, 1994; Brown, 1994)

  • Animal Foods
  • amphibians
  • reptiles
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • seeds, grains, and nuts
  • nectar


Mexican jays have many predators.

Conservation Status


Marta Hernandez (author), University of Arizona, Todd McWhorter (editor), University of Arizona.



uses sound to communicate


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.


uses smells or other chemicals to communicate

cooperative breeder

helpers provide assistance in raising young that are not their own


animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males


Having one mate at a time.


having the capacity to move from one place to another.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.


an animal that mainly eats all kinds of things, including plants and animals


reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


associates with others of its species; forms social groups.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"


uses touch to communicate


Living on the ground.


defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement


uses sight to communicate


Brown, J. 1994. Mexican Jay (*Aphelocoma ultramarina*). Pp. No. 118 in F Gill, A Poole, eds. The Birds of North America. Philadelphia: The Academy of Natural Sciences.

Burn, H., S. Madge. 1994. Crows and Jays: A Guide to Crows, Jays and Magpies of the World. New York: Houghton Mifflin Company.

Hopp, S., P. Jablonski, J. Brown. 2001. Recognition of group membership by voice in Mexican Jays, *Aphelocoma ultramarina*. Animal Behaviour, 62: 297-303.

Hopp, S. 10-15-2001. "Steven L. Hopp" (On-line). Accessed May 8, 2002 at http://eebweb.arizona.edu/faculty/hopp.