33RD REPORT OF THE CBRC: 2007 RECORDS 
Figure 12. The anomalous plumage and bill led most members to question the natural 
occurrence of this Yellow Grosbeak ( Pheuticus chrysopeplus ) photographed 1 August 
2006 at Keough Hot Springs, Inyo County. The black wings and large white patches 
at the base of the primaries are diagnostic for a male in its second year or older, yet 
the blackish or dusky on the crown appears to be retained juvenal feathers, a retention, 
to our knowledge, not matched by wild birds or specimens. The worn flank feathers, 
generally disheveled appearance, and lack of patterns of wear due to exposure to the 
elements on the tertials, inner greater coverts, outer primaries, and central rectrices 
suggest the bird could have been an escapee from captivity. 
Photo by Bob Steele 
light of the changing status of this species in California, but neither gained acceptance. 
Only four committee members favored acceptance of an adult at Folsom L. , PLA, 5-6 
Jan 1998 (2002-195A), though everyone agreed that this bird likely had substantial 
Slaty-backed Gull genes. Of primary concern was the mantle paler than expected. 
Mantle tone, color of head and neck streaking, bill shape, and body structure were 
also mentioned by various members as being inconsistent with typical L. schistisa- 
gus. Mantle-shade variation in the species has been widely discussed (Gustafson and 
Peterjohn 1994, King and Carey 1999, Olsen and Larsson 2003, Howell and Dunn 
2007). Whether this variation may be intraspecific or results strictly from hybridization 
remains uncertain. Hybridization of gulls is well known in the North Pacific rim (Bell 
1996, King and Carey 1999). The Slaty-backed is known to hybridize with the Vega (L. 
argentatus vegae), Glaucous-winged (L. glaucescens), and Glaucous [L. hyperboreus) 
Gulls. On the basis of current knowledge many individuals are better left unidentified. 
A gull in fourth basic plumage at Salton City, IMP, 21 Feb-7 Mar 1998 (1998-050 A) 
received majority support during its first round of recirculation but none in its final 
round, when all members agreed the bird had too many anomalous features. Molt 
schedule, eye color, primary-tip pattern, leg color, and mantle shade were inconsistent 
178 
