Figure 153. Throngs of birders enjoyed the adult Belcher’s Gull that unexpectedly turned up at the mouth of the Tijuana River in San Diego County on 3 August 1997 and then stayed there through 2 January 1998. This detailed sketch was made on 10 August (1997-120; Kimball L. Garrett).

Click image to see larger version.

 

Figure 231. The smudgy dark head, uniformly blackish mantle, and unmarked white belly of this Belcher’s Gull signify an adult in basic plumage. This widely seen individual, photographed on 10 August 1997 at the mouth of Tijuana River in San Diego County, furnished the only record of this South American species for western North America (1997-120; Larry Sansone).

 

 

 

 

 

 

BELCHER’S GULL Larus belcheri Vigors, 1829

Accepted: 1 (25%)	Treated in Appendix H: no
Not accepted: 3	CBRC review: all records
Not submitted/reviewed: 0	Large color image: see Figures

This species, part of the taxon formerly called the Band-tailed Gull, breeds along the Pacific coasts of Peru and northern Chile. Non-breeders range south to central Chile and north to Ecuador, exceptionally reaching Panama (Ridgely and Gwynne 1992). Four Florida records, believed to involve at least three birds, are generally treated as representing acceptable vagrants, despite the possibility of ship assistance (Robertson and Woolfenden 1992). The species was recently added to the ABA Checklist (Robbins et al. 2003).

California’s only accepted record of Belcher’s Gull, and the first for western North America, involves a widely seen individual present from 3 August 1997 to 2 January 1998 at the Tijuana River mouth in San Diego County (Figures 153, 231). This bird was thought to be molting from second alternate into third basic plumage, but may have been molting into full definitive basic plumage. By January the bird had acquired white feathers on the head that are part of alternate plumage in this species, six months out of synchrony for the species, as is typical of vagrants that undergo molt in the wrong hemisphere. See Patten (1998) for a discussion of this bird and of other gulls of the Southern Hemisphere that have appeared in the United States.

When identifying Belcher’s Gull outside of its normal range, observers should take particular care to eliminate the possibility of another very rare vagrant, the Black-tailed Gull (see the following species account). Lethaby and Bangma (1999) provided information on the distribution and identification of Belcher’s Gull.