260 AVES: KAPTOIiES. XLI. 



426. FALCO Linnaeus. FALCONS. (Lat., falcon.) 

 a. First primary only emarginate on inner web; tarsal plates small; sexes 



colored alike. 



b. Tarsus longer than middle toe and claw. 



c. Tarsus feathered in front more than half way down. (Hierqfalco 

 Cuvier.) 



820. P. rusticolus (L.). GRAY GYRFALCON. Bluish gray 

 above with dark bands ; lower tail coverts always with ashy ; young 

 plain above, streaky below. L. 24. W. 16. T. 10. Northern 

 regions ; var. obsoletus, S. to U. S. in winter. This form is darker, 

 the lower parts chiefly dusky. (Eu.} (Lat. rural.) 



cc. Tarsus not feathered more than half way down in front. ( Gennaia 

 Kaup.) 



821. F. mexicanus Schlegel. PRAIRIE FALCON. Grayish 

 brown, more or less barred and streaked. L. 18. W. 14. T. 8. 

 S. W., E. to 111., allied to the Lanier of Europe. 



bb. Tarsus not longer than middle toe, scarcely feathered below heel joint. 

 (Rhynchodon Nitsch.) 



822. F. peregrinus Tunstall. PEREGRINE FALCON. DUCK 

 HAWK. Blackish ash with paler waves ; top of head black ; below 

 whitish ; black cheek patches. L. 16. W. 13. T. 7. Northern 

 regions, not very common ; the American bird, var. anatum Bona- 

 parte, has the breast unstreaked. (Eu.) 



aa. Two primaries emarginate; tarsal plates enlarged in front, appearing 



like scutella. 



d. Tarsus about equal to middle toe ; basal joints of toes with small hex- 

 agonal scales. (^Esalon Kaup.) 



823. F. columbarius L. PIGEON HAWK. AMERICAN MER- 

 LIN. Ashy blue or brownish above with darker streaks ; lower 

 parts whitish or buffy, streaked with brown ; middle tail feathers 

 in with about 4 black bands ; in 9 with about 6 pale bands. 

 L. 13. W. 8. T. 5. U. S. (Lat., pertaining to a pigeon.) 



dd. Tarsus longer than middle toe ; basal joints of toes with transverse 

 scutella. (Tinnunculus Vieillot.) 



824. F. sparverius L. SPARROW HAWK. RUSTY CROWNED 

 FALCON. Back tawny ; wings bluish and black in ; seven black 

 blotches about head ; tail chestnut, with a broad black band in 

 <, and a narrow terminal one of white ; below white or tawny. 

 9 different, more streaky, the tail tawny with numerous narrow 

 darker bars ; back and wing coverts rusty barred with black. One 

 of the most active and courageous of the hawks ; a genuine falcon, 

 notwithstanding its small size. L. 11. W. 7. T. 5. U. S., 

 abundant. (Lat., relating to a sparrow.) 



