Photo by: Allan Hack - Taken in Bernal Historic Ranch Park, San Jose, CA - Originally posted to https://www.flickr.com/photos/aehack/26972565597/in/photostream/
Photo by: Parisa Ardekani – Taken at Scatter Creek Wildlife Recreation Area, Rochester, WA
Introduction
The California Scrub-Jay (A. californica) is a midsize passerine bird averaging at about 87 grams and 28-30 centimeters in length. Making this species between the size of a robin and a crow. This songbird looks for quiet, shrubby, oak woodlands despite its loud, curious, and assertive behavior (Crosbie, Souza, & Ernest, 2011). These birds can be found sitting atop of trees, perching on power lines and posts, feeding from feeders and bathing in backyard birdbaths. A. californica can also be found foraging on the ground and up in trees (Kaufman).
Juvenile -Photo by: Becky Matsubara- Taken in El Sobrante, CA Originally posted to https://www.flickr.com/photos/130819719@N05/18236461088
Most distinguishable by its bright royal blue coloring over most of the body. The scapulars and back are grey-brown, the ventral side and supercilium are white, and the lore and auriculars are dark grey. Everything else (coverts, primaries, secondaries, tail, head) is a brilliant blue. Juvenile plumage is grey on the dorsal side and white on the ventral, with the flight feathers and tail feathers molting first (Curry et al., 2017). The bill, legs, and feet are grey-black.
Formerly known as the Western Scrub-Jay, this species was recently officially split from Woodhouse’s Scrub-Jay in 2016 (Curry et al., 2017). These two species can be distinguished by slight differences in coloration. Woodhouse’s Scrub-Jay is a lighter blue and has a grayer ventral side, whereas the California Scrub-Jay is a brighter blue with a clearly defined blue necklace on the chest and has a white ventral side. The Woodhouse’s Scrub-Jay call is higher pitched than the California Scrub-Jay as well (Delaney, Zafar, & Wayne, 2008).
Distribution
California Scrub-Jay range in WA. Cassidy, K. (2002). California Scrub-Jay. Retrieved from http://www.birdweb.org/birdweb/bird/california_scrub-jay
The California Scrub-Jay can be found on the west coast of North America. From southern Washington near Puget Sound down to southern Baja California (Curry et a., 2017). This species is primarily distributed around the Cascade-Sierra mountain range (Sauer et al., 2017). However, more individuals have been spotted as far north as British Columbia as northern populations increase.
Habitat
Photo by: Max Sluiter – Originally posted to https://www.flickr.com/photos/max_911_fahrer/34888076736/
The California Scrub-Jay likes to inhabit open, shrubby areas, such as backyards, pastures, and orchards. Dense shrubs and oak trees are key to this species preferred habitat (Bardwell, Benkman, & Gould, 2001). Also, this bird species tends to avoid noisy areas (Crosbie et al., 2011).
Nesting
These jays like to nest low in trees (around 6-14 ft.) but will keep their nests well hidden amongst vines, mistletoe, and other foliage. They will primarily nest in oaks but are also known to nest in madrone trees as well. Both individuals in a breeding pair will construct the nest and finish in about 1.5 weeks (Curry et al., 2017). Pairs with begin construction late winter. Nests are basket shaped and made of twigs. The lining is made of a mixture of rootlets, fine plant fiber, and livestock hair (Kaufman).
When nesting, this species usually only has one brood per year and lays about 2-5 eggs. Incubation is done by the female and lasts 17-18 days and hatchlings leave the nest 18-22 days after hatching. Offspring are altricial and born naked with their eyes closed. Both parents will continue to feed the young for about 54 days after hatching (Kaufman).
Food Habits
A. californica are omnivores and opportunistic hunters and, like many other bird species, their diet varies with the seasons. In the summer A. californica eats a wide variety of insects. Acorns are the primary food source for many individuals of this species in the winter (Carmen, 2004). However, they will also eat other seeds, berries, eggs of other birds, small vertebrates, and human food scraps (Langen, 1999). Oak trees often have asynchronous fruiting times, making acorns a more substantial food item (Koenig et al., 2009). The young are fed insects and primarily moth caterpillars (Curry et al., 2017).
Photo by: Allan Hack – Taken in Hellyer Park, San Jose, CA – Originally posted to https://www.flickr.com/photos/aehack/39949485372/
A. californica are known to cache acorns for later consumption. Primarily storing between September-February and will recover the acorns between February-May. Located within their territory, individuals will store one seed per cache site. Up to 5,000 acorns can be cached by one individual in a single autumn season. Caches are later found using landmarks and the sun as a compass (Koenig et al., 2009).
Sounds
Common of other corvids A. californica make a wide array of vocalizations. Most commonly heard is the loud, raspy, evenly spaced, zeep/weep call (Audio provided below). These jays also have a song primarily used in courtship displays. This “whisper song” consists of soft, random, melodic notes commonly heard in calls of other bird species (Webber, 1984). The California Scrub-Jay also exhibits a loud chorus of vocalizations when they’ve seen a dead conspecific . This alarm call consists of multiple fast, and loud zeep-zeep-zeep. Individuals will belt out loud calls that attract other scrub-jays who will then join in (Iglesias, 2012).
(Jongsma, 2012)
Behavior
A. californica are nonmigratory and can be found high in trees, on wires, and on posts year-round (Carmen, 2004). The flight pattern alternates between bouts of fluttering and gliding making it seem under-powered or as if the individual is too heavy (Curry et al., 2017).
Photo by: Derek Keats -Taken in Santa Clara, CA- Originally posted to https://www.flickr.com/photos/dkeats/25319244899/in/photostream/
This assertive species will often fight or attack in order to defend or gain breeding territory. Usually resulting in loud calls, mobbing, pecking, and grabbing. Breeding pairs are monogamous and will defend their territory year-round (Carmen, 2004).
Courtship display starts a male individual with its tail and wings fanned out, moving its head back and forth while also stepping forwards then backwards. Pairs will also display courtship feeding in which both members will pass food to one another (Curry et al., 2017).
Population Trends and Conservation Issues
With the recent split, reported population data measures for the Western Scrub-Jay which combines both California Scrub-Jay populations and Woodhouse’s Scrub-Jay populations. Between 1968 to 2015 there has been no overall trend to A. californica populations in California. However, populations in Oregon, Washington, and B.C. have been increasing possibly due to climate change. The most abundant populations are located in coastal and central California. Overall, populations appear to be steadily increasing and are not significantly effected by human disturbance (Sauer et al., 2017).
Annual abundance in North Pacific Rainforest region (S05) based on data provided by BBS. Region S05 ranges from the southern tip of Alaskan panhandle, western coast of B.C., W.A., O.R., and northern coast of C.A. (Sauer et al., 2017).
One threat that may negatively affect populations is loss of food/habitat due to sudden oak death. However, due to this species variable diet SOD is not known to have significant impacts on effected populations (Monahan & Keonig, 2006).
About the Author
Haley Haradean is a college Junior at The Evergreen State College. She is currently studying to earn a degree in wildlife biology.
Contact: harhal25@evergreen.edu
Literature Cited
Bardwell, E., Benkman, C. W., & Gould, W. R. (2001). Adaptive geographic variation in western scrub-jays. Ecology,82(9), 2617-2627. doi:10.2307/2679940
Carmen, W.J. (2004). Noncooperative breeding in the california scrub-jay. Studies in Avian Biology, 28, 1-92. Retrieved from https://sora.unm.edu/node/138965
Crosbie, S. P., Souza, L. E., & Ernest, H. B. (2011). Estimating western scrub-jay density in california by multiple-covariate distance sampling. The Condor,113(4), 843-852. doi:10.1525/cond.2011.090152
Curry, R. L., A. T. Peterson, T. A. Langen, P. Pyle, and M. A. Patten (2017). California scrub-jay (Aphelocoma californica). The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi-org.evergreen.idm.oclc.org/10.2173/bna.cowscj1.03
Delaney, K. S., Zafar, S., & Wayne, R. K. (2008). Genetic divergence and differentiation within the western scrub-jay (Aphelocoma californica). The Auk,125(4), 839-849. doi:10.1525/auk.2008.07088
Iglesias, T., Mcelreath, R., & Patricelli, G. (2012). Western scrub-Jay funerals: cacophonous aggregations in response to dead conspecifics. Animal Behaviour,84(5), 1103-1111. doi:10.1016/j.anbehav.2012.08.007
Jongsma, J. (Recorder). (2012, September 9). Aphelocoma californica – california scrub-jay [Audio file]. Retrieved from https://commons.wikimedia.org/wiki/File:Aphelocoma_californica_-_California_Scrub_Jay_XC110976.mp3
Kaufman, K. California scrub-jay. Retrieved from https://www.audubon.org/field-guide/bird/california-scrub-jay
Koenig, W. D., Krakauer, A. H., Monahan, W. B., Haydock, J., Knops, J. M., & Carmen, W. J. (2009). Mast- producing trees and the geographical ecology of western scrub-jays. Ecography,32(4), 561-570. doi:10.1111/j.1600-0587.2008.05617.x
Langen, T. A. (1999). How western scrub-jays (Aphelocoma californica) select a nut: effects of the number of options, variation in nut size, and social competition among foragers. Animal Cognition,2(4), 223-233. doi:10.1007/s100710050043
Monahan, W. B., & Koenig, W. D. (2006). Estimating the Potential Effects of Sudden Oak Death on Oak-Dependent Birds. Biological Conservation,127(2), 146-157. doi:10.1016/j.biocon.2005.08.005
Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr, K. L. Pardieck, J. E. Fallon, and W. A. Link. (2017). The North American Breeding Bird Survey, Results and Analysis 1966 – 2015. Version 2.07.2017 USGS Patuxent Wildlife Research Center, Laurel, MD
Webber, T. (1984). Form and function of the long-range calls of Scrub Jays, Aphelocoma coerulescens obscura (Doctoral dissertation). University of Florida. Retrieved from http://ufdc.ufl.edu/AA00003426/00001/4j
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