had been
remarking and comparing the tails of the male and female swallow, and
this ere any young broods appeared; so that there was no danger of
confounding the dams with their _pulli_: and besides, as they were then
always in pairs, and busied in the employ of nidification, there could be
no room for mistaking the sexes, nor the individuals of different
chimneys the one for the other. From all my observations, it constantly
appeared that each sex has the long feathers in its tail that give it
that forked shape; with this difference, that they are longer in the tail
of the male than in that of the female.

Nightingales, when their young first come abroad and are helpless, make a
plaintive and a jarring noise, and also a snapping or cracking, pursuing
people along the hedges as they walk; these last sounds seem intended for
menace and defiance.

The grasshopper-lark chirps all night in the height of summer.

Swans turn white the second year, and breed the third.

Weasels prey on moles, as appears by their being sometimes caught in
mole-traps.

Sparrow-hawks sometimes breed in old crows' nests, and the kestril in
churches and ruins.

There are supposed to be two sorts of eels in the island of Ely. The
threads sometimes discovered in eels are perhaps their young: the
generation of eels is very dark and mysterious.

Hen-harriers breed on the ground, and seem never to settle on trees.

When redstarts shake their tails they move them horizontally, as dogs do
when they fawn: the tail of a wagtail, when in motion, bobs up and down
like that of a jaded horse.

Hedge-sparrows have a remarkable flirt with their wings in breeding-time;
as soon as frosty mornings come they make a very piping, plaintive noise.

Many birds, which become silent about Midsummer, reassume their notes
again in September, as the thrush, blackbird, woodlark, willow-wren,
etc.; hence August is by much the most mute month, the spring, summer,
and autumn through. Are birds induced to sing again because the
temperament of autumn resembles that of spring?

Linnaeus ranges plants geographically; palms inhabit the tropics, grasses
the temperate zones, and mosses and lichens the polar circles; no doubt
animals may be classed in the same manner with propriety.

House-sparrows build under eaves in the spring; as the weather becomes
hotter, they get out for coolness, and nest in plum-trees and
apple-trees. These birds have been known sometimes to bu