By John V. Richardson Jr.

5 May 2008


Western Scrub Jay.jpg

Western Scrub-Jay



Corvidae Family; AOU 4810; IUCN Red List: Not Evaluated

(Vigors, 1839)


Description/Field Marks:  11 - 13” (28-33 cm).  Robin-sized, but large, strong bill and long tail make it appear larger.  Heads, wings and tail blue (conspicuous when it glides after a long, undulating flight); back dull brown and underparts light gray; white throat offset by incomplete blue necklace” (AS, #505, p. 630).  Now, considered one of at least three sister species including Santa Cruz Island (insularis) and Florida (coerulescens).


Vocalization: commonly, “a shreep, often in short series” (NG, p. 169).  Eighteen calls, according to Webber (1984), classified into four acoustic categories as: “scolds, zeep/scolds, zeeps, zhraanhs, and shlenks in one group; weeps and screlches in another; the chuk, given only by males; and the rattle, given only by females”; variously labeled as harsh, loud, noisy, rasping, raucous, and scratchy by humans.


Courting Displays:  “Courting male hops around female with his head erect, tail spread and dragging” (Birder’s Handbook, p. 404); reproductive status by age three or older, according to Corey (1994), but as early as yearlings, according to Carmen (1984).


Male/Female: According to Cornell, “Sexes look alike,” but other sources claim female slightly larger.  Monogamous, “long-term pair bond,” according to Birder’s Handbook, (1988), p. 404.


Diet: insects, fruit, seeds, grain, and nuts (especially pinyon pine and acorns which have been cached during winter and early spring) as well as “small reptiles and mammals” NG, 169; in late spring, they will “eat the eggs and young of other birds” (AS, p. 485), especially among Wrentits when Western Scrub-Jays are “nest building and egg laying” except if Wrentits exhibit higher levels of scolding behavior, according to Preston (2004).  See “Behavior” below.


Nesting:  open cup; “in Florida, confined to scrub oak” (AS, p. 484); “in trees, bushes, shrubs, usually fairly low…Compactly built, well-constructed platform of twigs, mixed with moss and dry grass.  Lined with hair and fine roots (no mud),” according to Harrison, p. 144).  One brood, rarely two, according to Birder’s Handbook, p. 404.


Eggs:  oval shape; buff or dull green, spotted with dark brown; 4-6 in number, commonly 3-4; average size, 27.6 mm x 20.5 mm (AS, p. 484).


Incubation:  15-17 days; “Male feeds female before and during incubation” according to BH, p. 404.  Female does most brooding, male guards. 


Behavior:  not shy, even inquisitive, perching in the open in trees and shrubs; tame, hand feeding of peanuts in cities.  Forages on ground with its strong legs.  In wild, caching of seeds/nuts suggests good spatial memory, according to Olson (1989).  “Jays often help the flock by standing sentry during foraging; together they mob would-be predators” NG, p. 169.  According to Cornell, “The Western Scrub-Jay feeds on parasites [especially ticks] on the body of mule deer, hopping over the body and head of the deer to get them.”  Long, undulating flight.


Habitat/Local Sites:  According to Cornell, “found in oak and juniper scrub, chaparral, oak and pine woodland, riparian woodland, gardens, and orchards.” Woodland and chaparral, but does not breed in low scrub because it needs watch posts” (AS, #505, p. 630); usually fairly low, three to thirty feet, but tree tops and telephone poles and lines in early morning.


Range:  Washington east to Wyoming, south to Texas, California, and Mexico” (AS, p. 630) and central Florida.


Did you know:  More than two jays are called a band or party; “They also share a tendency to carry off and hide brightly colored objects” (AS, p. 485).  The record longevity for a banded western Scrub-Jay is 15 years, 9 months, according to http://www.pwrc.usgs.gov/BBL/homepage/long3930.htm.






“All About Birds: Western Scrub-Jay” at http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Western_Scrub-Jay.html (access 5 May 2008).


Audubon Society Field Guide to North American Birds, 1977.


Carmen, William J.   Behavioral Ecology Of The California Scrub Jay (Aphelocoma Coerulescens Californica): A Noncooperative Breeder with Close Cooperative Relatives,” PhD Dissertation, University Of California, Berkeley, 1988.


Corey, Kennon A.  “Demography of the Santa Cruz Island Scrub Jay,” MS Thesis, California State University Long Beach, 1994.


Harrison’s Field Guide to Western Birds’ Nests (1979).


National Geographic Field Guide to Birds, edited by Mel Baughman (2004).


Olson, Deborah J. “Comparative Spatial Memory in Birds,” PhD Dissertation, University of Massachusetts, 1989.


Preston, Kristine L. “From population demography to individual behavior: Testing the effects of food abundance and nest predation risk in an arid-shrubland songbird,” PhD Dissertation, University of California, Riverside, 2004.


Webber, Tom. “Form and function of the Long-Range Calls of Scrub Jays, Aphelocoma Coerulescens Obscura,” PhD Dissertation, University of Florida, 1984.



Other References:

Correia, Sergio P. C., et al. "Western Scrub-jays Anticipate Future Needs Independently of Their Current Motivational State." Current Biology 17 (no. 10, 2007): 856-861.

Curry, Robert Lawrence; A. Townsend Peterson, and Tom A. Langen.   Western Scrub-jay: Aphelocoma Californica.  Birds of North America Inc., 2002.

Raby, C. R.; D. M. Alexis, A. Dickinson and N. S. Clayton "Planning for the Future by Western Scrub-jays." Nature 445 (22 February 2007): 919-921.


“Western Scrub-Jay or California Jay” at http://www.oiseaux.net/birds/western.scrub-jay.or.california.jay.html (accessed 5 May 2008).




FIELD NOTES:   Seen Big Morongo Canyon Preserve, Loop Trail, about 8:30AM on 3 May 2008 (cool; no breeze).                                                                                                      R;tw