The White-throated Swift 
following season. The Black-chin has strong local attachments and is 
very persistent. T. C. Wueste, of San Diego, tells 1 of one bird which, 
having been robbed consecutively three times in one season, built a 
fourth nest upon the selfsame twig and laid therein a fourth set of eggs, 
which she was allowed to possess in peace. Another bird, 2 having 
probably lost her nest when it was just ready for occupancy, dropped 
her eggs into the nest of a House Finch—defended her usurpation, too, 
in all probability, for nothing can stand before an irate hummer. 
The comings and goings of the Black-chinned Hummer depend, more 
than in the case of any other California species, upon the season and the 
state of the flower crop. A wet winter, with abundance of food assured, is 
followed by a large influx of Black-chins; and in exceptional circumstances 
they fairly swarm. Tree tobacco (Nicotiana glauca), an introduced plant 
which is on the increase with us, is sure to abound with Black-chins; and, 
to mention only one of a dozen other favorites, so is the red larkspur 
(Delphinium cardinale). Those which have not followed the flowers up 
into the mountains with the advancing season will swarm about a century 
plant in August. A lady near Santa Barbara tells me that she has seen as 
many as sixty at once about a single plant. Of their occurrence in Los 
Angeles County, Joseph Grinnell says: 3 “This species arrives in Pasa¬ 
dena from the middle of April to the first week in May, and the majority 
disappear by the last of July. Extreme records at Pasadena are April 3 
(1895), and September 3 (1895). By the first of July, when the vege¬ 
tation of the foothills becomes dry and flowers cease to bloom, the hum¬ 
mingbirds are found in countless thousands at higher elevations (6000 to 
8500 feet), where summer is just dawning.” 
No. 187 
White-throated Swift 
A. 0. U. No. 425 . Aeronautes saxatalis (Woodhouse). 
Synonyms. —Rock Swift. Mountain Swift. Rocky Mountain Swift. 
White-throated Rock Swift. 
Description. — Adults: Chin, throat, breast, middle line of belly, and a conspic¬ 
uous patch on flanks, white—also outer edge of first primary and tips of secondaries; 
1 Condor, Vol. IV., March, 1902, p. 39. 
2 Frank Stephens in Life Histories of N. A. Birds: Bendire, Vol. I., p. 199. 
3 Pub. 2, Pasadena Acad. Sci., 1898, p. 27. 
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