The TREE FALCON (_Hypotriorchis subbuteo_) is but little inferior to
those we have described, either in its powers or the nobility of its
appearance. The members of the family of which this bird is the type
are smaller than the Falcons we have mentioned, and are distinguished
by their elongated bodies, comparatively long and sickle-shaped wings,
which extend as far as, or in some instances beyond, the extremity of
the tail. The Tree Falcon is twelve inches long, and thirty broad; the
wing measures nine and a half, and the tail nine inches; the female is
one inch and a half longer, and from two to three inches broader than
her mate. The entire upper portion of the body is blueish black, the
head of a greyish shade; the nape is spotted with white, the quills
black, bordered with reddish yellow, and marked upon the inner web with
from five to nine reddish irregularly oval patches. The tail-feathers
are slate colour above, grey beneath, and ornamented on the inner web
with eight irregular reddish-yellow spots, which form a kind of border;
the two middle feathers are without these spots. The lower part of the
body is white or yellowish white, marked from the head downwards with
longitudinal black streaks; the wings and lower tail-covers are beautiful
rust red; the beard is very plainly indicated; the eye is dark brown,
the naked ring by which the latter is surrounded, the cere, and feet are
yellow; the beak is dark blue at its tip, and of a lighter shade towards
its base. In the plumage of the young birds the blueish-black feathers
that cover the back are bordered with reddish yellow; the light spot
upon the nape is larger than in the adult, and of a yellow colour; the
lower part of the body whitish yellow, marked with long black streaks;
the wings, lower wing-covers, and clothing of the legs are yellowish, the
feathers of which the latter are formed having black shafts.
This species inhabits the whole continent of Europe and the cooler
portions of Asia; it also visits India in large numbers during the
winter, but is rarely seen in Northern Africa. Eversmann tells us that
it is found in great numbers in the country near the Ural Mountains. In
the central portion of our continent it usually makes its home amongst
the trees of the open country, rarely visiting the forests, except during
the course of its migrations; in these countries it is a summer guest,
leaving about September or October, and returning in April. The flight of
the Tree Falcon is extremely rapid, and bears some resemblance to that
of the Swallow; the wings are held somewhat arched, and their stroke
is short and quick; its evolutions through the air are often extremely
beautiful, and are characterised by light and graceful gyrations as it
rises aloft or sinks rapidly to the ground. The Tree Falcon, as its name
suggests, usually prefers to perch upon trees, and but rarely seeks the
ground, except when engaged in devouring its prey. The migratory season
commences in autumn, and during their journeyings the pairs keep together
with the utmost constancy, in spite of the many fights and squabbles
that arise amongst the members of the party. The voice of this bird is
clear and not unpleasing, though it consists but of a single note. In its
habits it is extremely intelligent, and so very shy and cautious that
it only ventures to yield to sleep when the darkness of night has fully
closed in.
Field Larks appear to be the favourite food of the Tree Falcon, though
it by no means objects to other birds--indeed, it is regarded as a
formidable enemy even by the most rapid of the Swallow tribe. Naumann
tells us that an instance came under his own observation in which a
Swallow was so terrified at the appearance of one of these redoubtable
enemies that it fell as though dead to the ground, and only ventured to
open its eyes and give signs of life some little time after he had taken
it in his hand. Occasionally, if hotly pursued and other means of escape
appear impossible, Larks will seek refuge and hide themselves near the
protecting feet of the ploughman or of horses, as they wend their way
about the fields. Swallows endeavour to save themselves by uniting into
flocks, and whirling at a respectful distance above the heads of their
dread pursuers. The Tree Falcons will also catch insects when upon the
wing, and devour large numbers of grasshoppers, dragon-flies, and ants
during the whole time that the latter are engaged in swarming.
The eyrie is usually built upon a high tree, and resembles those of other
Falcons as regards its exterior, but the interior is lined with wool,
hair, or some other soft and elastic material. The eggs are laid in July,
and are from three to five in number, and of a greyish white or greenish
colour, covered with light reddish-brown spots, which are most thickly
distributed over the broad end. Lenz tells us that one Tree Falcon will
destroy no fewer than 1,095 small birds annually. This species was
formerly trained for hunting purposes, and is, when domesticated, one of
the most intelligent and docile of its family.