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Variation of Birds in a State of Nature by Frank Russell, 1892

Variation of Birds in a State of Nature by Frank Russell, 1892, Page 24

varies more. [Taking?] them the average amount of variation of each species ([illegible] line of totals) [we?] may arrange them in the series given below in which the habit of the bird is also noted. 

I. F. aquila 24.75%
II. [illegible] 28%
III. N. [illegible] 33.5%
IV. S. Magna 55.62%
V. B. [illegible] 69%

The two species of migratory birds vary more than the non migration. This is probably due to the frequent change of environment with a probable attendant change of food. The [solitary?] species shows a marked tendency to vary in color. The difference in [size?] between the sexes is [illegible] due to this [illegible] habits, the males tending to decrease as the forces of sexual selection which cause the males of [illegible] birds to increase in size an [wanting] here as in [illegible] bird generally. The unusual [illegible] necessary in the female [illegible] the growth of the young doubtless causes greater development.
[illegible] habits tend to produce males larger in proportion to the size of the females and to the development of secondary sexual characters.
[Noting] the most constant parts of each species we find that in nearly all the wing is most

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varies more. [Taking?] them the average amount of variation of each species ([illegible] line of totals) [we?] may arrange them in the series given below in which the habit of the bird is also noted. I. F. aquila 24.75% II. [illegible] 28% III. N. [illegible] 33.5% IV. S. Magna 55.62% V. B. [illegible] 69% The two species of migratory birds vary more than the non migration. This is probably due to the frequent change of environment with a probable attendant change of food. The [solitary?] species shows a marked tendency to vary in color. The difference in [size?] between the sexes is [illegible] due to this [illegible] habits, the males tending to decrease as the forces of sexual selection which cause the males of [illegible] birds to increase in size an [wanting] here as in [illegible] bird generally. The unusual [illegible] necessary in the female [illegible] the growth of the young doubtless causes greater development. [illegible] habits tend to produce males larger in proportion to the size of the females and to the development of secondary sexual characters. [Noting] the most constant parts of each species we find that in nearly all the wing is most