and only found in winter, but it becomes more numerous
towards the north till, in Normandy and Picardy, it is as
abundant at that season as in any part of England. On the
other hand the Black Crow is said to be resident throughout
France, and in the south very plentiful in winter. In
Belgium and Holland it is also resident and common. In
Germany, the Elbe is stated to mark roughly the boundary
of the breeding-limits of the two forms—the Black Crow
occupying the districts to the westward and the Grey Crow
those to the eastward of that river, but in Upper Lusatia,
Anhalt, Brunswick (Journ. f. Orn. 1871, p. 212), and
Mecklenburg both are found breeding; and in the duchy last
named hybrids frequently occur, as they do also in Holstein.
In Denmark, however, the Grey birds almost entirely prevail,
the Black being very rare, and even in that part of Germany
where the Black Crow breeds the Grey predominates in
winter. In Savoy the Black form is common and resident,
but the Grey is rare and does not breed. The latter however,
says Dr. Salvadori, is common and resident throughout
the whole of Italy and its islands, while he believes that the
former is confined to Upper Italy and is wanting from
Tuscany southwards, but further observations are hereon
required. In Piedmont hybrids between the two occur. In
the Austrian Dominions their distribution has not as yet
been clearly defined, and with regard to some parts of it the
evidence is to a certain extent conflicting, though the Grey
Crow seems generally to pervade the whole. The Black
Crow also occurs in Moravia and Bohemia, but in the last it
is chiefly if not entirely confined to the wooded highlands of
the west. In Austria proper it is very rare, though abundant
in the Tyrol. In Styria it appears in winter, but it is not
recorded by modern writers from Carinthia. It occurs, however,
in Servia, Wallachia, Bulgaria and Macedonia, but its
asserted existence in Greece must at present be regarded as
doubtful—while the Grey Crow inhabits all these and the
intervening countries, extends to most of the islands of the
Greek Archipelago, and was found breeding in Crete by Col.
Drummond-Hay.
Thus it will be seen that though our knowledge of the
subject is still imperfect as regards a few minor details, it
admits of our arriving at some important generalizations,
and the result shews that the geographical distribution of the
two forms supplies no better proof of their specific distinctness
than does any of the other characteristics before considered.
The Black Crow is found at the extreme western as at the
extreme eastern limits of the range of both, while the Grey
Crow occupies the most northern as well as the most southern
countries frequented by either. It cannot therefore be said
that one is a western and the other an eastern race, or that
one is a northern and the other a southern. So far the only
rational mode of regarding the Black and Grey Crows would
appear to be as members of a single dimorphic species, and
the inability to point out why this species should possess
that admittedly exceptional quality is no more an argument
against that view, than is the inability to explain why a
wholly black plumage should prevail in nearly all the species
of Gorvus, while in a few others the black should be varied
by grey or white. It must also be remembered that the
present case does not stand as one of simple local variation as
is that of so many other birds—some of them even belonging
to the same genus, as the Daw, presently to be noticed,
and the C. splendens of the Indian Region, of which Himalayan
examples have an ash-coloured breast and collar, which
is darker in specimens from Bengal and Southern India,
and darker still in those from Ceylon (Ann. Nat. Hist. ser. 2,
xiii. p. 214), while in some of those from Burma and Siam
nearly all trace of the grey is lost (Ibis, 1867, p. 298) .
A more important objection, however, to the view above
taken may be raised, and one that has not before been stated.
By many naturalists it has long been held that the infertility
of hybrids between any two forms affords the strongest
ground for considering them distinct species whether the
* Mr. Hume suggests (Stray Feathers, 1874, p. 480 aud 1875, p. 144), that
these deserve specific recognition. Mr. Sharpe notices (Cat. B. Br. Mus. iii.
p. 33) a specimen, said to he from Malacca, of the ordinary dark form. When
more is known about the dark-eyed and white-eyed Crows of Australia the case of
our own birds may be further iRustrated (cf. E. P. Ramsay, Ibis, 1865, p. 303).