usually placed in the fork * of a birch or willow—sometimes
very near the ground, or even, though rarely, in a tuft of
grass upon it, and seldom at a greater height than eight or
ten feet. It is almost always of remarkable neatness and
beauty, built of bents and a few small twigs, occasionally
intermixed with lichens and shreds of bark, and lined with
willow-down, feathers (chiefly such as are white) or reindeer’s
hair. The eggs, usually five or six in number, measure from
'77 to -61 by from *52 to *45 in.f In ground-colour they
vary from french-white to deep greenish-blue—especially when
fresh, and are marked with several shades of light red,
reddish-brown or, very exceptionally, even brownish-black:
some trace of marking is nearly always discernible but the
reddish colour is frequently diffused in pale freckles all over
the shell, while at other times it is collected in distinct spots
or blotches which occasionally form a zone.
The breeding-season over, the various families collect in
flocks that ever increase as summer draws to a close and at
this season the cocks assume their most brilliant tints. In
the far north of Europe hardly a grove of alders or willows
by river or lake but then harbours a flock that finds more
than sufficient food in the countless insects which throng
such spots, and so these birds continue till the first frosts
check their supplies. As the temperature decreases with the
rapidly-lengthening nights a few weeks suffice to strip the
trees bare, and on the destruction of those leafy retreats, with
the insect-worlds they sheltered, the Redpolls have to adopt a
vegetable instead of an animal diet, in the pursuit of which
the flocks mostly quit their former haunts, betaking themselves
whithersoever seeds, it matters little of what kind, are
to be found. By far the largest number set out on the annual
migration which in time brings them to this and other
southern countries, but no inconsiderable portion remain
in the land of their birth. These are fitted for the cold of an
* In Norway the Editor once saw a nest placed in the top of a birch-stump the
middle of which had rotted away leaving a kind of cup, formed by the upstanding
bark, just of a convenient size to hold the bedding for the eggs.
t A dwarf specimen, obtained by the late Mr. Wolley and now in the Editor’s
possession, is the smallest bird’s egg he has ever seen, being only '43 by '36 in.
arctic winter by an extraordinary growth of plumage, their
new feathers, assumed at the autumnal moult, bearing very
long white fringes, which not only greatly change the appearance
of the birds, by almost entirely masking their darker
colours, but form a warm clothing that affords the wearers
an efficient protection against the rigours of the climate.
This growth indeed takes place in all, but among those
which flee from the severity of the northern regions at this
season it bears no comparison as to extent with that which
obtains among those that abide under high latitudes and
thus muffled in their thick vestments await the return of
spring.
But another and yet more remarkable seasonal change
occurs in these birds, of which Wolley during his long residence
in Lapland seems to have been the first observer,
though his full explanation of it has not been made public.
It had long been known that examples differed greatly in the
size and especially in the length of the bill, and many
naturalists were inclined to believe that this difference indicated
two races, if not species, of Redpoll.t A certain amount
of it indeed was obviously rather apparent than real, being
due to the length of the feathers on the bird’s face, and thus
the bill of a specimen obtained in winter always seemed much
shorter than that of one procured in summer; but from repeated
examination of birds killed out of the same flock he
satisfied himself that during the latter season the horny
covering of the mandibles was constantly growing longer,
and attributed the fact to the softer nature of the food
then eaten, observing that when winter really set in, and the
birds were living solely on hard seeds, the edges and tip of
the mandibles were rapidly worn down, so that the bill at the
beginning of spring became considerably shorter than it
was at the end of the preceding summer. If this mode
* Wolley’s residence extended over five summers and three winters: his views
on this subject were first made known to the Editor in 1855. They are confirmed
by Gloger’s happy conjectures published some eighteen months afterwards
(Journ. fur Orn. Nov. 1856, pp. 433-440). .
+ The large-billed birds were described by Brehm (Handb. p. 280) m 1831
as forming a distinct species which he called Linaria holbcelli.