Murdoch on Migration of Birds. 
75 
Their large size and the peculiarity of their markings, so different 
from those of any Junco that I have ever seen, suggested a suspicion 
that they might be the eggs of the Junco aikeni , but this Mr. Car- 
ter does not regard as probable. The nests of the first two present 
nothing peculiar in their construction. They are saucer-shaped, 
and are merely loose aggregations of grasses and stems of plants, 
lined with fine material of a like nature. 
Mr. Carter is confident that he has never met with more than 
three forms of Junco in Colorado, namely, caniceps , oregonus , and 
aikeni ; the latter two he has known since 1859, when he first met 
with them in large numbers near Central City, but his observations 
have been mainly confined to the higher altitudes. He met with 
aikeni in the greatest abundance on the eastern slope of the main 
range, at an elevation of eight thousand feet, twelve years before 
Mr. Aiken first brought it to the attention of naturalists. The lat- 
ter’s first specimens were procured in the lower and eastern limit of 
their habitat, which will account for his speaking of their scarcity 
and their straggling habits. The same winter (1871-72) Mr. Car- 
ter, in his camp, a few miles west, and at an altitude greater by 
some three thousand feet, met with these individuals every day, in 
flocks of from a few individuals to those of a hundred or more. 
Mr. Carter is also quite sure that all the adults of this species, of 
both sexes, are always found to possess the white wing-bands well 
defined, and that it is only the birds of the first year, in immature 
plumage, that furnish what has been mistaken for an intermediate 
form between this species and the typical Junco liyemalis. Mr. 
Carter has never, to his knowledge, met with oregonus or aikeni in 
Colorado during the breeding season, but thinks that they all move 
farther north to nest. 
EFFECTS OF THE WARM WINTER ON THE MIGRATION 
OF BIRDS. 
BY JOHN MURDOCH. 
It is well knowm that in ordinary winters all our summer resi- 
dents and autumnal visitors have taken their departure from the 
neighborhood of Boston by the month of December. From the 
