452 NORTH AMERICAN BIRDS. 



contained two eggs, exactly resembling those of the T. coluhris, and measur- 

 ing .51 by .32 of an inch. 



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

 ley, March 20. 



Mr. J. K. Lord, one of the English commissioners of the Northwestern 

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

 ern slope of the Rocky Mountains. Tliis was near a lake, by the margin of 

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

 he found a sweet gummy sap exuding plentifully 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 oft' and devouring these captive 

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

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

 prisoned insects. Upon securing one of these birds, he ascertained that it 

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

 insect-eaters. Not only on this occasion, but many times afterwards, Mr. 

 Lord saw this bird pick the insects 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 swamps, 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 country around Guaymas, where amid the 

 scanty vegetation they had constructed their nests in tlie month of April. 

 He also afterwards found them on Dry Creek and the Cosumnes Paver. 



According to tlie observations of Mr. Eidgway, 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 with the 

 Selasphorus rufus in the western portion, and with S. platycerms to the east- 

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

 nine thousand feet in the mountains. 



