294 BIRDS OF THE REPUBLIC OF PANAMA PART 4 



All the records from the Canal Zone are quite old and were identified 

 before mensural differences between this species and O. Philadelphia 

 were known. Stone (Proc. Acad. Nat. Sci. Philadelphia, vol. 70, 1918, 

 p. 274) listed O. tolmiei from the Canal Zone. The Field Museum in 

 Chicago has 2 females collected at Colon by J. F. Ferry on March 14 

 and 16, 1908. The Smithsonian has a female collected by E. A. Gold- 

 man at Gatun March 2, 1911, that fits the mensural characters of tolmiei 

 (examined by W. Lanyon). 



Specimens collected by Monniche (Blake, op. cit.) on October 15 

 and May 16 (to the extent correctly identified as tolmiei) would repre- 

 sent the extreme dates for which this species is known in Panama. 



The specimens from Panama agree with those of the nominate race 

 from California and Oregon in being brighter green above and brighter 

 yellow below than monticola of Colorado and New Mexico. Cox (Auk, 

 1973, pp. 190-191) describes occasional hybridization between this 

 species and O. Philadelphia in southwestern Alberta. In non-breeding 

 plumage O. tolmiei cannot be safely separated in the field from O. 

 Philadelphia and must be identified by measurements, especially the 

 relatively longer tail compared to wing; thus many identifications, even 

 of specimens, made without determining wing and tail relationship (as 

 described in Lanyon and Bull, Bird-Banding, 1967, pp. 187-194) are 

 likely to be erroneous. 



GEOTHLYPIS TRICHAS (Linnaeus): Common Yellowthroat, 

 Reinita Gargantiamarilla Comun 



T urdus Trichas Linnaeus, 1766, Syst. Nat., ed. 12, 1, p. 293. (Maryland.) 



Small, upper surface mostly buffy olive; throat (and on male much 

 of undersurface) yellow; belly buff; male with black mask across fore- 

 crown and face. 



Description. — Length 108-129 mm. Adult male, forecrown and side 

 of head black, bordered by white except on sides of throat; crown buffy 

 olive, becoming more greenish on back; wings dull green, with remiges 

 edged yellowish green; tail yellowish green; throat and breast bright 

 yellow fading to light buffy brown on belly; undertail coverts pale 

 lemon yellow; bend of wing bright yellow; underwing coverts white. 



Adult female, forecrown light brown, fading to buffy olive on rest of 

 upper surface; wings and tail as male; side of face dull tawny-olive; 

 throat pale yellow, tinged with buff on breast and fading to light buffy 

 brown on rest of undersurface; undertail coverts more yellowish. 



Migrant and winter visitor from the north. Rare in Bocas del Toro 



