General: Steller’s Jays (Cyanocitta stelleri) are bold, social and extremely vocal birds that can be found in the mountainous areas of the North American west. They may best be known for their dark blue coloration and lack of white undersides. Be cautious of these vividly colored and inquisitive birds when picnicking, as they have been known to steal unguarded fare. Steller’s Jay populations are healthy and expanding and are listed as Least Concern on the IUCN Red List.
Description: Steller’s Jays are large, robust birds that reach adult weights of 3.5 to 5 oz. and lengths of 11.75 to 13.5”. They have full, long tails, large heads with thick, straight black bills and rounded wings that open to a span of over 17”. Steller’s Jays, like Blue Jays, have prominent crests that sit erect atop their heads. These two species are the only two in North American that have easily distinguishable crests1.
Steller’s Jays are identifiable by their allover dark coloration, lacking the light underparts common of many species. Their heads are charcoal in color with subtle white or blue markings and black crests. Their bodies are dark cobalt blue accented by vivid blue and black barring on the wings and tail. Sexual dimorphism is minimal within this species, with females only being slightly fainter in color and with slightly less barring than males. Juvenile Steller’s Jays lack the brilliance of adults and instead are brown or gray with less prominent crests.
Geographic variations occur across the seventeen known subspecies of Steller’s Jays. These differences can include greater amounts of blue or black across the bodies and crests, and variations in head sizes and patterning.
Steller’s Jays are intelligent, noisy and inquisitive birds that spend most of their time foraging and exploring their habitats. On the ground and in trees they move with bold hops (pausing often to investigate their surroundings) and in the air they travel with graceful, long and steady wing beats (their wings rarely extending past horizontal2.)
Steller’s Jays are extremely social birds, traveling in flocks of mating Steller’s Jay pairs as well as in mixed-species flocks. Their populations are built upon complex patterns of social hierarchies and dominance. To display aggression, two jays may partake in aerial fights, grasping and pecking at each other during flight. Social standings may also be determined through crest displays, wing spreading (to express submission) and an activity called “Aggressive Sliding.” To ward off predators, such as raptors, Steller’s Jays unite into mobs to use vocal and physical intimidation3.
Extremely vocal birds, Steller’s Jays are capable of a broad range of sounds and calls, including mimicking (the likes of dogs, cats, squirrels, chickens, other birds, and even some machines4.) Other sounds include squawks, screams, rattles, soft warbles, and piercing sheck sheck sheck screams5. Adult jays, while usually some of the most vocal birds in their habitats, are quiet and discreet when raising their young or robbing nests6.
Steller’s Jays have been known to live to approximately 16 years old.
Habitat: Steller’s Jays reside in mountainous coniferous and mixed forests of the North American West, where they can be spotted in the high canopy. They may also be found in arid woodlands in the American southwest and Mexico. Their habitats also include parks, campgrounds, and suburban areas.
Location: Steller’s Jay populations are generally resident and inhabit coniferous and mixed woods forests in western North America, from the southern coast of Alaska, through the Rocky Mountain Region (into eastern Colorado) and south into Mexico and Central America at elevations of 3,000’ to 10,000’. Along the Pacific Coast, Steller’s Jay populations tend to be found at lower elevations7.
Although Steller’s Jays are generally resident, some populations may migrate to lower elevations during winter months. Large irruptions in the fall and winter may also cause populations of Steller’s Jays to move into southern California, deserts of the American southwest, and the Great Plains. There has also been accidental population movement into Illinois, Nebraska, Kansas and central Texas8.
Diet: Steller’s Jays are generalist foragers, searching for food on the ground and in trees. Their omnivorous diets consist of two-thirds vegetable matter, including seeds, berries, and nuts. These jays are capable of carrying several large nuts or seeds simultaneously within their mouths and throats. Because they have developed spatial understanding and memory, Steller’s Jays are able to bury and store nuts and seeds for winter food caches. In addition to their own caches, it is common for Steller’s Jays to raid caches of other birds during winter months. Their diets also include insects, small rodents, reptiles, invertebrates and carrion. Steller’s Jays are habitual nest robbers and are known to eat eggs and nestlings. Populations living in close proximity to humans will eat garbage, bird feed and picnic fare9.
Reproduction: Steller’s Jays form long-term monogamous pairs that tend to remain together year round. Breeding generally occurs within dense coniferous forests, and begins with courting displays called “Sexual Sliding10.” Steller’s Jays have one brood per year. Nesting sites are selected by both mates who then collect materials and build the nest together. These nests are usually above ground, located on horizontal branches close to the trunk of a tree. One of only two species of New World Jays to use mud as a building material (the other is the Blue Jay,) Steller’s Jays construct cup-shaped nests of stems, moss, leaves, and sticks (all held together with mud.) These nests may be up to 17” in diameter, 7” tall and 2.5” to 3.5” in depth and are lined with pine needles, animal hair, rootlets and sometimes paper. Females are able to lay one egg per day, with typical clutches containing 2 to 6 blue-green eggs spotted with olive, brown or purple. The eggs are 1” to 1.4” in length and are incubated by the females for 16 days, although males have been known to share in incubation duties11. Both parents share in feeding their young. The chicks molt for the first time in 2 weeks and begin to fly at around 3 weeks of age, shortly after fledging. Although the fledglings begin foraging for their own food at one-month-old, parents continue to provide food for an additional month after their young fledge12.
As Blue Jay populations expand west, hybrids with Steller’s Jays are becoming more and more common.
Notes of Interest: Steller’s Jays received their namesake from naturalist Georg Steller. He first discovered this species in 1741 while exploring an Alaskan island as part of the crew of a Russian exploratory ship. Other species that share their namesake: Steller’s sea lions and Steller’s Sea-Eagles13. Over the last two decades, Steller’s Jay populations have expanded, infiltrating a broader range of habitats. As a result, the Steller’s Jay has become a much more common resident of towns and cities14.