452 NORTTT AMERICAN BIRDS. 



contained two eggs, exactly resembling those of the T. colubris, and measnr- 

 ing .51 by .?)'2 of an inch. 



Afterwards Mr. W. W. Holden obtained a specimen in tlie Colorado Val- 

 ley, March 20. 



Mr. J. K. Lord, one of tlie Englisli commissioners of the Northwestern 

 Boundary Survey, met with this species near his camping-place on the west- 

 ern slope of the Eocky Mountains. This was near a lake, by the margin of 

 which, with other trees, grew a number of the black birch. On tliese trees 

 he found a sweet gummy sap exuding j)lentifully from splits in the bark, 

 and on this sap hosts of insects, large and small, were regaling themselves. 

 As the sap was very sticky, numbers of the smaller winged insects were 

 trapped in it. Busily employed in picking off and devouring tliese captive 

 insects were several very sombre-looking Humming-Birds, poising tliem- 

 selves over the flowers, and nipping off, as with delicate forceps, the im- 

 ]uis(ined insects. Upon securing one of these birds, he ascei'tained tliat it 

 belonged to this species. This was pretty satisfactory proof that tliey are 

 insect-eaters. Not only on this occasion, Init many times afterwards. ]\Ir. 

 Lord saw tliis bird pick tlie insect.s from the tree ; and the stomachs of those 

 he killed, on being opened, were filled with various kinds of winged insects. 

 He found this bird lingering around lakes, pools, and swamj^s, where these 

 birches grow. They generally build in the birch or alder, selecting the fork 

 of a branch high up. 



This species bears a very close resemblance in size, appearance, and mark- 

 ings, to the common eastern species, but is readily distinguishable by the 

 difference in the color of the chin and the shape of the tail. 



In the spring of 1851, on a trip to Sonora, Mexico, Dr. Heermann found 

 these birds abundant in the arid countiy around Guaymas, where amid the 

 scanty vegetation they had constructed their nests in the month of Ajiril. 

 He also afterwards found them on Dry ('reek and the Cosumnes liiver. 



According to the observations of ]\Ir. Ridgway, this species has quite an 

 extended distribution in the West. He found it in varying abundance from 

 the Sacramento Valley, in California, to the Wahsatch and Uintah Moun- 

 tains in Utah. 



At Sacramento it was more abundant than the C. anna, nesting in the 

 door-yards and in gardens, but particularly in the thick copses of small oaks 

 in the outskirts of the city. In the Great Basin it associated witli the 

 Sdasplwrus rnfas in the western portion, and with S. platycercus to the east- 

 ward, nesting everywhere, from the lowest valleys to a height of eight or 

 nine thousand feet in the mountains. 



