than the Cuckoo, which keeps within certain bounds yet flies about
briskly, or the Godwit which, though holding to its few square yards on
the ground, executes most tiring and extensive flights above the marsh.

Of all the migrants, however, the behaviour of the Ruff is perhaps the
most strange, and though it has long been known that these birds have
their special meeting places where they perform antics and engage in
serious strife, yet it is only within recent years that the primary
purpose of these gatherings has been ascertained--that purpose being the
actual discharge of the sexual function. Mr. Edmund Selous has carried
out some exhaustive investigations into their activities at the meeting
places, and he makes it clear that each bird has its allotted position.
He says, for example, that "It begins to look as though different birds
had little seraglios of their own in different parts of the ground,"
that "each Ruff has certainly a place of its own," or again that "this
Ruff indeed, which I think must be a tender-foot, does not seem to have
a place of its own like the others." Nevertheless it is only at the
meeting places that they have their special positions; there is no
evidence to show that each one has a special territory, wherein it seeks
its food, as the Warbler has, and therefore some may think that we are
here confronted with behaviour of a different order. But we must bear in
mind that the process has been adjusted to meet the requirements of
different species: the size of the territory, the period of its daily
occupation, the purpose which it serves--these all depend upon manifold
relationships and do not affect the principle. Why it has been
differentiated in different circumstances we shall have occasion to
discuss later; for the moment it is enough that at the end of its
migratory journey each Ruff occupies one position on the meeting ground.

[Illustration: Territorial flight of the Black-tailed Godwit

Emery Walker ph.sc.]

Now birds that are paired for life, whose food-supply is not affected by
alternations of climate, have no occasion to desert the locality wherein
they have reared their offspring, and so their movements, being subject
to a routine which would tend to become increasingly definite, must in
the course of time and according to the law of habit formation become
organised into the behaviour we observe. Is it necessary, therefore, to
seek an explanation of their tendency to remain in