d with carnivorous birds. It
is said[350] that as many as eighteen species have been used in Europe
for hawking, and several others in Persia and India;[351] they have
been kept in their native country in the finest condition, and have
been flown during six, eight, or nine years;[352] yet there is no
record of their having ever produced young. As these birds were
formerly caught whilst young, at great expense, being imported from
Iceland, Norway, and Sweden, there can {154} be little doubt that, if
possible, they would have been propagated. In the Jardin des Plantes,
no bird of prey has been known to couple.[353] No hawk, vulture, or owl
has ever produced fertile eggs in the Zoological Gardens, or in the old
Surrey Gardens, with the exception, in the former place on one
occasion, of a condor and a kite (_Milvus niger_). Yet several species,
namely, the _Aquila fusca_, _Haliaetus leucocephalus_, _Falco
tinnunculus_, _F. subbuteo_, and _Buteo vulgaris_, have been seen to
couple in the Zoological Gardens. Mr. Morris[354] mentions as a unique
fact that a kestrel (_Falco tinnunculus_) bred in an aviary. The one
kind of owl which has been known to couple in the Zoological Gardens
was the Eagle Owl (_Bubo maximus_); and this species shows a special
inclination to breed in captivity; for a pair at Arundel Castle, kept
more nearly in a state of nature "than ever fell to the lot of an
animal deprived of its liberty,"[355] actually reared their young. Mr.
Gurney has given another instance of this same owl breeding in
confinement; and he records the case of a second species of owl, the
_Strix passerina_, breeding in captivity.[356]

Of the smaller graminivorous birds, many kinds have been kept tame in
their native countries, and have lived long; yet, as the highest
authority on cage-birds[357] remarks, their propagation is "uncommonly
difficult." The canary-bird shows that there is no inherent difficulty
in these birds breeding freely in confinement; and Audubon says[358]
that the _Fringilla_ (_Spiza_) _ciris_ of North America breeds as
perfectly as the canary. The difficulty with the many finches which
have been kept in confinement is all the more remarkable as more than a
dozen species could be named which have yielded hybrids with the
canary; but hardly any of these, with the exception of the sisk