PICOIDES. 287 



a\ No white on back nor on top of head. 



Length about 9.50-10.00, wing 4.85-5.25, tail 3.60, culmen 1.40-1.60. Eggs 

 .95 X -71. Mab. Northern North America, south to northern border of 

 United States, and farther on high mountain ranges, especially westward, 

 where breeding on Sierra Nevada south to at least 39°. 



400. P. arcticus (Swains.). Arctic Three-toed Woodpecker, 

 a^. Back (especially along middle line) varied with white, and top of head also usu- 

 ally more or less mixed with white. 

 b^. Back with detached white bars, always less in width than the black inter- 

 spaces; white postocular streak or stripe usually indistinct, black bars 

 on sides usually broader, and adult female frequently with whole toj) of 

 head solid black — never very conspicuously varied with white. 



Wing-coverts always uniform black; length about 9.00, wing 4.40- 

 4.60 (4.37), tail 3.10-3.75 (3.34), culmen 1.10-1.25 (1.17). Eggs .92 

 X .70. Hab. Northern North Amei'ica east of Eocky Mountains ; 

 south, in winter, to northern border of United States. 



401. P. americanus Brehm. American Three-toed Woodpecker. 



b^. Back with more or less confluent white bars, always broader than black 



interspaces, or else longitudinally blotched or striped with white; white 



postocular streak usually broader and more conspicuous; black bars on 



sides usually narrower, and adult female usually with top of head much 



varied with white. 



c^ Back usually distinctly barred with black (rarely continuously white 



along middle line), secondaries more distinctly spotted with white 



(sometimes wing-coverts also spotted, more or less numerously, with 



white), white spots on quills larger, and female sometimes with 



white prevailing on top of head ; length about 9.50, wing 4.50-4.70 



(4.58), tail 3.10-3.75 (3.41), culmen 1.10-1.25 (1.22). Hab. Alaska, 



north of the mountains, south to Nushagak, and eastward through 



arctic British America to Fort Eeliance, Great Slave Lake. 



401a. P. americanus alascensis (Nelson). Alaskan 



Three-toed Woodpecker, 

 c*. Back continuously white along the middle line, with few if any black 

 bars, the markings being mostly longitudinal ; secondaries less dis- 

 tinctly spotted with white, white spots on quills smaller, wing 

 coverts never (?) spotted or speckled with white, and adult female 

 never (?) with much white streaking on top of head ; length about 

 9.50, wing 4.65-5.00 (4.93), tail 3.20-3.65 (3.49), culmen 1.1.5-1.30 

 (1.26), the bill more slender than in alascensis. Hab. Eocky Moun- 

 tains, north to Fort Liard, Fort Simpson, Fort Kenai, and Kadiak, 



south to New Mexico 4016. P. americanus dorsalis Baird. 



Alpine Three-toed Woodpecker. 



