There are two types of jays that can be seen while hiking in the Silicon Valley area: the California scrub jay and the Steller’s jay. Learn how to tell the difference between these two native jay birds while on the trail.
What are jays?
Jays are intelligent birds belonging to the family Corvidae. Corvids include crows, ravens, and magpies. As with other corvids, jays are known for their complex social behaviors, vocal communication, and adaptability.
Physical differences between the scrub jay and Steller’s jay
The California scrub jay (Aphelocoma californica) is a medium-sized bird with blue plumage on its wings, tail, and head. Scrub jays have a lighter coloration on the underparts—often a soft gray to whitish belly—with blue and gray markings across the back and shoulders. Black patches of feathers run from the eyes down the cheek.
The Steller’s jay (Cyanocitta stelleri) is identifiable by its prominent crest, which it frequently raises or lowers depending on mood or environmental conditions. The Steller’s jay has dark blue feathers covering its lower body. The upper body from the tips of the wings to the crest is black or deep charcoal gray with two light blue stripes on the forehead.
Habitat preferences
While both jays can overlap in the foothill regions of Silicon Valley, their preferred habitats usually differ:
California scrub jay habitat
The scrub jay primarily inhabits oak woodlands, suburban gardens, brushy chaparral, and areas with scattered trees or shrubs. Scrub jays are comfortable in open areas, frequently seen in parks, residential neighborhoods, and along urban trails.
Steller’s jay habitat
A shyer bird than the scrub jay, the Steller’s jay prefers denser, coniferous forests or wooded foothills, typically at higher elevations. Within Silicon Valley, hikers commonly observe Steller’s jays in shaded areas such as the redwood forests of the Santa Cruz Mountains like Big Basin, Sanborn Park, or Rancho San Antonio Preserve.
Behavior
California scrub jays are notably curious, often boldly approaching human visitors, particularly in areas where people frequently offer food. They forage primarily for insects, acorns, seeds, and berries. Notably, scrub jays frequently cache—or hide—acorns, contributing significantly to oak regeneration within their habitats. They are socially interactive but usually appear singly or in pairs rather than large groups.
Steller’s jays exhibit a somewhat bolder, more territorial behavior compared to scrub jays. Known for their assertive personalities, these birds often vocalize loudly when disturbed or defending territory. Their diet is similarly diverse, feeding on nuts, berries, insects, and occasionally small animals or eggs from other bird species.
Calls
Scrub jay: Calls are typically loud and harsh, but also melodious and varied. Scrub jays frequently produce a sharp “shreep” or “squawk,” often repeated as part of a communication pattern between individuals.
Steller’s jay: Vocalizations tend toward louder, harsher, and more repetitive notes, often described as a loud “shack-shack-shack” or “jee-ah.” Their calls are generally more aggressive-sounding, especially when alarmed or defending their territory.
