WESTERN SCRUB-JAY
Aphelocoma californica
Order:  Passeriformes

Family:  Corvidae

 Alpha Code:  WESJ             AOU#:  481.0

Band size:  2-3
     The Western Scrub-jay is not so much a common bird in the Santa Monica Mountains as well as in urban areas across southern California sitting on shrubs and calling loudly.  It is a bold and aggressive bird coming within a few meters of us at the banding station to pick up crumbs from donuts and other snacks, especially goldfish.  In urban areas, it boldly scolds and attacks cats.  Yet we know when it has eggs or chicks in the nest, as scrub-jays become conspicuously quiet.

    The Western, Island, and Florida Scrub-jay were once a single species, but are now split into three species.  The Western Scrub-jay is found throughout California with the exception of the Central Valley, the hot deserts, and higher elevations.  Note the proper name of this bird is not a "jay" but a scrub-jay (with a hyphen).

   As with all members of the family Corvidae (crows and jay), it is a largish passerine (28 cm and 80 g) and very intelligent.  The Western Scrub-jay is dark blue above with a brownish patch on the back and with a long blue tail. The underparts are whitish to grayish with a distinct blue breastband.  The white eyebrow is also conspicuous.

Bird Banding:  This is a strong, aggressive bird with strong legs, so it is often a handful for banders with small hands.  The help of a second bander is necessary.  Using the leg gauge is a good idea.  Although size 3 seems large, I often find size 2 is too small.  One problem is that there is a large difference between these two sizes (one mm).  Forty-six percent of our birds use a 3 band.

     

    For ageing this bird, juv/HY birds have a gray back and do not have the dark blue.  The roof of the mouth changes color with age, grayish in juv/HY and becoming completely black in AHY/ASY birds.  One trick I have learned to speed up banding as well as not having to pry open the bird's mouth to look at this trait is take mental note of the inside of its mouth as it tries to bite you while removing the bird from the net.   

     Pyle describes the tail shape as an useful ageing characteristic (longest r - r5 is 10-20 mm in HY/SY birds vs 3-15 mm in AHY/ASY birds), but I often find the rectrices quite worn living in the chaparral.

     Since it is a large bird, I find that molt limits and fault bars are often useful characteristics to use.

     In general, we band scrub-jays (n = 51) as young birds (67% are HY/SY birds) but rarely as adults.  We see a number of scrub-jays banded but rarely, if ever, catches these "wiser" individuals.