[EBB Sightings] Briones Blue Grosbeak

Folks:

It is always good to hear from Steve.

The late Ned Johnson described a systematic range expansion of Blue 
Grosbeak from the southwest (Johnson, N. K.  1994.  Pioneering and natural 
expansion of breeding distributions in western North American birds. A 
Century of Avifaunal Change in Western North America (J. R. Jehl, Jr. and 
N. K. Johnson, eds.).  Studies in Avian Biology No. 15:27-44.)

In the category of dueling "almost-finished" breeding bird atlases, here 
are a couple of paragraphs from the Santa Clara Breeding Bird Atlas:

         "Price (1898) stated that the Blue Grosbeak was "rather rare" at 
Stanford.  However, he did not include any details of his observations, and 
Grinnell and Wythe (1927) knew of only one record in the San Francisco Bay 
area by the beginning of the 20th century, a bird seen at Hayward on 1 May 
1876.  Grinnell and Miller (1944) described salicaria's California breeding 
range as including coastal southern California, the Sacramento and San 
Joaquin valleys, and Owens Valley.  Although they noted coastal 
observations extending to the San Francisco Bay region, they were not aware 
of any breeding west of the Central Valley.  Johnson (1994) described a 
significant northward range expansion from population centers in Arizona 
and New Mexico, starting in the 1960s.  Perhaps coincidentally, breeding 
well west of the Central Valley was discovered in 1958 when a pair nested 
south of Hollister, San Benito County, on 1 Jun 1958 (Audubon Field Notes 
13:398 1959).  Although sporadic reports of spring Blue Grosbeaks were 
obtained subsequently in the San Francisco Bay region and as far north as 
Del Norte County, it was not until 1987 that nesting was suspected in 
eastern Alameda County (Am. Birds 41:486 1987) and a repeat nesting 
occurred in San Benito County (Am. Birds 41:1485 1987).  Nesting was 
confirmed in eastern Alameda County and the upper Salinas Valley, Monterey 
County, in 1990 (Am. Birds 44:1183 1990, Roberson 1993).  On 25 Jul 1995, a 
pair with at least two fledged young were found near San Pablo Bay in 
Sonoma County for the first breeding record from the immediate San 
Francisco Bay region (Burridge 1995, Field Notes 49:978 1995).
         "The first record of a Blue Grosbeak in Santa Clara County was of 
a male banded on 22 Jul 1989 at the Coyote Creek Riparian Station (CCRS) 
near Alviso (L. Richard Mewaldt, pers. comm.).  Single second-year males 
were banded at CCRS on 11 Jun 1992 and 17 Jun 1992 (Gina Barton, pers. 
comm.) and a male was found along the Pajaro River at Sargent on 25 Apr 
1993.  Following the atlas period, a male was found singing in an extensive 
ruderal area along Coyote Creek north of the Riverside Golf Course in 
Morgan Hill on 27 Apr 1994 (Stephen C. Rottenborn, Michael M. Rogers; 
county notebooks).  It remained in this area through at least 16 May, but 
no evidence of nesting was obtained.  A male was again found at this 
location 3-6 May 1995, but again no evidence of nesting was observed 
(Stephen C. Rottenborn, county notebooks).  However, on 2 Sep 1995 a female 
Blue Grosbeak was found in willows along Llagas Creek above Bloomfield Road 
accompanied by three begging dependent fledglings, one of which was fed by 
the female (Stephen C. Rottenborn, Michael M. Rogers; pers. comm.).  Llagas 
Creek is bordered by levees in this agricultural area southeast of 
Gilroy.  A dense growth of willows along the creek bottom and tall, dense 
weedy vegetation along the levee sides provided suitable habitat for this 
first county breeding record."

Bill

At 08:18 PM 5/29/06, Steve Glover wrote:
>Hi all,
>A young male BLue Grosbeak was reported at Briones on
>6/16/1985. The recent bird could well be a migrant but
>breeding was either confirmed or thought possible at
>several sites in the county during the breeding bird
>atlas that were away from normal Central Valley
>haunts, including on Lawrence Rd near Blackhawk and in
>the Nortonville area of Black DIamond Mines Regional
>Park. Also, now that I think of it, near Marsh Creek
>Res. west of Brentwood.
>Pasted below is text from the almost-finished Contra
>Costa County Breeding Bird Atlas.
>Good birding,
>Steve Glover
>Dublin
>Blue Grosbeak  (Guiraca caerulea)
>Opening comments
>The brilliant deep blue plumage and warbling song of
>the Blue Grosbeak does much to brighten the weedy
>areas of east county during the hot summer at a time
>and place where there is often little avian activity.
>Males often sing endlessly atop brambles and telephone
>wires while their more subdued mate goes about
>familial responsibilities below.
>Current status and distribution
>Blue Grosbeaks are fairly common summer residents of
>far eastern county, where they inhabit willow clumps,
>drainage ditches and weedy, bramble-choked fields.
>Riparian habitats featuring anything but willows and
>blackberry brambles are rare in east county but a few
>pairs inhabit narrow strips of oaks and walnuts in the
>Brentwood area. Some favored locations where they are
>particularly easy to find include Jersey Island, the
>north end of Bethel Island, Holland Tract and Orwood
>Rd.
>Prior to the atlas project, Blue Grosbeaks were almost
>unknown away from traditional breeding areas in the
>Delta. Quite a few birds though, were detected during
>the atlas project well out of range and possibly
>prospecting for potential nest sites. Amongst the
>locations was the Nortonville side of Black Diamond
>Mines Regional Park, the Concord Naval Weapons
>Station, just south of Marsh Creek Res. (a pair), and
>near the south end of Lawrence Rd. near Blackhawk.
>Prior to the atlas project, the only county records of
>true migrants (colonizers?) was one at West Pittsburg
>22 May 1979 (AB 9/79) and a young male at Briones
>Regional Park 16 June 1985 (AB Wi 85).
>Historical occurrence
>Grinnell and Wythe (1927) make no mention of Blue
>Grosbeaks from the eastern portions of the Bay region
>but Grinnell and Miller (1944) did include eastern
>Contra Costa County on their range map, though
>apparently based upon assumed range rather than
>sightings or specimens. The first known county record,
>strongly suggestive of breeding, is now thought to
>have been three birds at Bethel Island 6 July 1956
>(Quail 8/56).
>         Blue Grosbeaks apparently begin to arrive in Contra
>Costa County about 20 April, though the first singing
>male detected during the atlas project was 27 April.
>The first pair wasn't recorded until 5 May, though
>they doubtless occurred earlier. The lone instance of
>an adult carrying nest material was discovered 22 May.
>Adults were observed carrying food on five occasions
>spanning the narrow window of 25 June to 6 July. A
>fledgling was noted 30 June. In years prior to and
>after the atlas project, apparent family groups have
>been noted on Bethel Island deep into August (pers.
>obs.).
>Conservation
>         Blue Grosbeak populations in the eastern and
>northeastern portions of the county may be reasonably
>secure since development of such low-lying areas is
>inherently risky. Central Valley birds on slightly
>higher ground, however, are highly vulnerable to
>recent unrestrained development.
>--- judi sierra  wrote:
> > Does anyone know if they've been seen before in
> > Briones?
> >
> >
> > This morning I found a singing blue grosbeak at the
> > top of Briones Crest
> > trail.
> >
> >
> >
> > Good birding!
> >
> > John Poole
> >
> >
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