1908] Grinnell—Biota of the San Bernardino Mountains. 23 
the following entry: ‘‘Many species which bred far below us 
are now moving up the mountains. Families of black-headed 
erosbeaks, bushtits, western gnatcatchers, scores of Parkman 
wrens, and even a good many linnets, are moving up along the 
Santa Ana where, a month ago, none of these species were to be 
seen. The western and Traill flyeatchers have invaded the do- 
main of the gray flycatcher; and California yellow, lutescent, 
golden pileolated and black-throated gray warblers are passing 
in regular migratory fashion, though not necessarily as yet going 
beyond the confines of the mountains. The great majority of 
these are birds-of-the-year, many in full first-winter plumage, but 
some in the midst of moult, or even still in complete juvenal 
plumage. Black phoebes, all closely enough serutinized being 
juvenals, have become excessively common along the streams, the 
first having been seen July 5. 
“All this influx of population appears to be mainly due to the 
conspicuous abundance now of both vegetable and insect food, 
particularly the latter. Geometrid larve are abundant on the 
fol®@age of willows and oaks; even the various conifers harbor 
myriads of lary; and the air teems with gnats, flies, and beetles. 
Normally seed-eating birds are taking advantage of this supply, 
and such species as the western chipping sparrow and lazuli bunt- 
ing are seen carrying larvee to their full-grown but teasing off- 
spring. 
“A special feature of the past three weeks or more has been 
the influx of numerous hummingbirds (black-chinned, Anna, 
rufous, and Allen). Those taken have their gullets crammed 
with gnats and small spiders, and are many of them imeonven- 
iently fat to make into good skins. <A significant thing has been 
the bursting into bloom of vast quantities of scarlet pentstemions 
(P. labrosus and P. bridgesii) at just about the time of the ar- 
rival of the hummers. Was this merely coincidence, or is it a 
case of chronological co-adaptation? The structure of these 
pentstemons seems to show a clear condition of ornithophily, and 
I have never seen these flowers visited by any sort of insect. The 
red-plumaged: rufous and Allen hummingbirds, of rapid and 
erratie flight, harmonize to a surprising degree with the shim- 
mering patches of scarlet pentstemons.”’ 
