system. Now observe that soon
after the flock arrived in the meadow, single males detached themselves;
there was no hesitation, they just retired from their companions and
settled in their respective territories. They were not expelled, for if
their leaving had been compulsory much commotion would have preceded
their departure, and their return would certainly not have been
welcomed. A reference to the plan will make the position clearer; the
neutral zone inhabited by the flock is there shown as situated in one
corner of the meadow, the territories that fell under observation are
plotted out as far as possible to scale, and the more important zones of
conflict are also marked.

The males spent part of their time in their respective territories and
part with the flock, so long as it remained in existence. When a male
was in its territory it avoided companions and was openly hostile to
intruders; when it was with the flock it wandered about with companions
in search of food. The contrast between the two modes of behaviour was
very marked, and it was evident that the gregarious instinct was
gradually yielding its position of importance to the new factor--the
territory. If there had been no flock, if a few solitary individuals had
appeared here and there and had established themselves in different
parts of the meadow, one would have had no definite evidence of the
strength of the impulse in the male to seek a position of its own, one
could only have argued from the general fact of males flocking in the
winter and isolating themselves in spring that something more than
accident was required to explain so radical a change. But since the
birds returned in a flock to the ground upon which they intended to
breed, and since the flock occupied temporarily part of the ground
whilst the partitioning of the remainder was still proceeding, it was
possible to gauge the strength of the impulse, which was forcing the
males to isolate themselves in particular areas of ground, by comparing
it with the impulse to accompany the flock--and the measure of its
intensity was the rapidity with which the latter impulse yielded its
position of importance.

Like the Lapwing, the Coot and Moor-Hen are easily kept under
observation, and since many individuals often breed in proximity, more
than one can be watched at the same moment; moreover the area occupied
by each male generally embraces an open piece of water as well as part
of the fringe of re