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2. When both sexes build, the males still have the broader

skulls and beaks, the latter being useful for defensive purposes.


3. When the hen alone builds, she has the broader skull

and beak.


The reason is not far to seek, for breadth of skull means

more brain area and increased intelligence : also breadth of

skull gives a wider and, therefore, firmer base to the beak,

enabling its owner to inflict more powerful blows without

injury to itself.


Quite recently I discovered that the form of the beak,,

although the feature doubtless recognized by male birds, is not

the only one by which sexes may be distinguished ; inasmuch as

some birds, though I believe only those which pursue their

females, have a very distincft outline of wing, that of the male

being specially constructed for speed. This is certainly the case

both with the Ifinnets and Skylarks: and I am gradually having

my dead birds mounted w r ith a view to the study of this

character, which will, I think, prove more or less useful to

ornithologists. I had hoped that it would have enabled the

Pigeon-fancier to make himself happy, but I was only able to

examine seven birds, three cocks and four hens, and all that I

could find was a difference of about an inch in the length of the

inner secondaries; whether the males always have this greater

basal depth of wing I cannot say, but it would be worth looking

into.


With the slight differences of tint which sometimes dis¬

tinguish the sexes of Finches, such as the buff tinting of the

underparts in the Magpie-Mannikin and the pink line at the

base of the upper mandible in the female Diamond Sparrow,

with similar small but infallible guides, the readers of my

“Foreign Finches in Captivity” will be familiar; but all these

species can be with certaint}^ recognized by outline of beak. The

females of very many species can be approximately guessed at

by their inferior size and slimmer or sometimes stouter build,

the typical Finches being usually stouter and the Grass-finclies

slimmer in outline.



