1318 
REPORT OF THE CHIEF OF ENGINEERS. 
causes: first, actual increase in the length of the tail; second, actual decrease in the 
length of the wing. 
By the above arrangement the four forms will stand as follows : 
Passerella iliaca { Merr.).—Habitat: Eastern province of North America ; breeds from 
British America northward, across to month of Youkon. In migrations to eastern edge 
of great plains; occasional in spring in Colorado (Maxwell) fide Ridgway. 
Passer ella iliaca, var. schistacea Bd.—Habitat: Middle province ; restricted by western 
edge of plains and eastern slope of Sierras ; an occasional straggler in Kansas and Cali¬ 
fornia in fall. 
Passerella iliaca, var. lownsendi (Aud.).—Habitat: Pacific province; breeds in north¬ 
ern Sierras; Southern California in winter; contiued to western slope of Sierras. 
Passerella iliaca , var. megaryncha Bd.—Habitat: Southeru Sierras, eastern as well as 
western slope ; probably a resident species. 
21. Pipilo maculatus (Sw.), var. megalonyx Bell.—Long-spurred Towhee. 
I saw but few Pipilos, and these on the brushy foot-hills, or in the chaparral of the 
mountain sides. Tney were extremely shy, so much so that I failed to secure speci¬ 
mens. They were doubtless of the above variety, as the variety oregonus is a more 
northern form. 
22. Pipilo chlorurus (Towns.).—Green-tailed Finch. 
Not uncommon in October; x>robably rather numerous in summer. 
ICTERIDHX 
23. Scolecoplxagus cyanocephalus (Wagl.).—Brewer’s Blackbird. 
Rather numerous during the fall months ou the borders of Lake Tahoe. 
CORVIDvE. 
24. Corvus corax L.—Raven. 
Not nearly so common in the mountains as in the valleys below. 
25. Picicorvus columbianus (Wils.).—Clarke’s Crow. 
A very abundant resident throughout the pine-region, appearing to live exclusively 
upon the pine-seeds. 
26. Pica melanolenca L., var. Jiudsonica (Sab.).—American Magpie. 
As noticed in the previous list, scarcely reaching into the mountains, and but few 
were seen on the immediate borders of Lake Tahoe. 
27. Cyanura slelleri Gm., var. frontalis Ridg.—Blue-fronted Jay. 
Very abundant on the eastern slope, here replacing the var. macroloplia of the Rocky 
Mountains. A permanent resident. 
TYRANNIDiE. 
28. Empidonax hammondi (Xantus).—Hammond’s Fly-catcher. 
This was the sole representative of the family noted by us in the mountains. It 
probably is not uncommon as a summer resident. 
CAPRIMULGIDJE. 
^9. Antrostomus nuttalli (Aud.).—Nuttall’s Poorwill. 
Not uncommon in fall in the shrubbery of the open mountain sides, but avoids the 
pine-woods. 
TROCHILHLE. 
30. SelasjAwrus rufus (Gm.).—Rufous-backed Humming-bird. 
I he only humming-bird seen by us in the mountains. Very numerous in September 
and the lirst of October. 
An unaccountable fact to us in connection with the present bird is the apparent ab¬ 
sence of all adult males in the fall from localities and regions where the young and fe- 
