The Descent of Man

one. It should, however, be borne in mind, that
the chief season for catching birds does not
begin till September, so that with some species
partial migrations may have begun, and the
flocks at this period often consist of hens alone.
Mr. Salvin paid particular attention to the sexes
of the humming-birds in Central America, and
is convinced that with most of the species the
males are in excess; thus one year he procured
204 specimens belonging to ten species, and
these consisted of 166 males and of only 38 females.
With two other species the females were
in excess: but the proportions apparently vary
either during different seasons or in different
localities; for on one occasion the males of
Campylopterus hemileucurus were to the females
as 5 to 2, and on another occasion (66.
'Ibis,' vol. ii. p. 260, as quoted in Gould's 'Trochilidae,'
1861, p. 52. For the foregoing proportions,
I am indebted to Mr. Salvin for a table of
his results.) in exactly the reversed ratio. As
bearing on this latter point, I may add, that Mr.