WESTERN YELLOW-THROAT. 119 



that have struck Som])rei'o Key lighthouse. The only species that 

 has struck in larger numbers during- the six years in which records 

 have been kept is the black-throated bhie warbler. 



At St. Louis, after September 20, the numbers of the Mar3dand 

 yellow-throats grow rapidly less, until at the end of the month only 

 a few loiterers remain. These iinall}^ disappeared for the year on 

 October 1, 1896, October 2, 1887, and October 4, 1895. Final depar- 

 ture occurred at Onaga, Kans., September 27, 1891, September 25, 

 1892, September 30, 1893, September 30, 1891, September 23, 1895, 

 and September 27, 1898. , 



681a. Geothlypis trictias occidentalis Brewst, Western Yellow-throat. 



Breeding range.— From the central portion of the Great Plains to 

 the Pacific slope the western 3^ellow-throat is one of the best- known 

 warblers. It is a bird of the plains and lower foothills, scarcely nest- 

 ing above 6,000 feet, and breeds from northern Lower California, north- 

 ern Chihuahua, and western Texas to AVashington, Montana, and South 

 Dakota. 



Whiter range. — In winter the bird is found chiefly in western Mexico, 

 as far south as Tepic. 



Spring niigration. — The influence of temperature on migration is 

 shown strikingl}^ in the case of the western yellow-throats. The birds 

 arj'ive at just about the same time — second week in Ma}^ — on the plains 

 of north-central Colorado and at Great Falls and Columbia Falls, 

 Mont., the latter place almost 600 miles farther north, but enjoying 

 at this period of the year an equal degree of w^armth with the Colorado 

 plains. But almost a month earlier than this, southern British Col- 

 umbia is reached by the Pacific yellow-throats that wintered in the 

 warm valle3^s of California lying as far north as the plains of north- 

 central Colorado which during the winter season can support no warbler 

 life. 



681c. Geotlilypis trichas arizela Oberh. Pacific Yellow-throat. 



This form inhabits the Pacific coast region, and breeds from British 

 Columbia to Lower California. It winters from Tepic and Mazatlan 

 in western Mexico, north to California. 



68 le. Geothlypis trichas sinuosa Grinnell. Salt Marsh Yellow-throat. 



Occurs in the salt marshes about San Francisco Bay, where it is a 

 permanent resident. 



682. Geothlypis belding-i Kidgw. Belding Yellow-throat. 



The Belding yellow-throat is a western species, resident in Lower 

 California. 

 682.1. Geothlypis poliocephala Baird. Rio Grande Yellow-throat. 



This Mexican species occurs near Brownsville, Tex., in the lower 

 Rio Grande Valley. 



