INTRODUCTION. 
XV 
out from natural causes, was wholly absent for a hundred years; but, owing to the replanting of j)ine-forests, 
the conditions favourable to its welfare are returning, and a fresh Introduction has reinstated it. Other 
birds, such as the Crane, Spoonbill, Bittern, Avocet, and the Ruff, which were once very common, have 
now, owing to the draining of our fens and marshes, no resting-places where they could dwell iu peace and 
unmolested. Thus it will he seen that by man’s industry in effecting improvements certain natural 
productions are greatly interfered with. 
With regard to the exact enumeration of the birds frequenting the British Islands there must always be 
considerable difficulties, inasmuch as many persons would hesitate to include in our lists such species as have 
from time to time strayed over from America, or others which we may reasonably suppose to have escaped 
from confinement. With these difficulties in view I have restricted the additions to our list of native birds, 
i 
with only a few exceptions, to those species pertaining to the fauna of the Old World which, without 
constantly residing in our islands, have from time to time appeared therein, and whose visits oft repeated 
may ultimately entitle them to a permanent place in our lists. I may state with tolerable accuracy that the 
total number of our species is about three hundred and fifty. 
If the supposed number of birds inhabiting the globe be about 10,000, it must be admitted that the British 
Islands have their due proportion of them. Of course it would be quite out of place to institute a comparison 
between our country, or even the whole temperate region of either hemisphere, and the tropics, where bird- 
life is so redundant, in accordance w'ith the profusion of fruits and insects upon which they mainly subsist. 
It must be conceded by every one who has paid attention to general ornithology, that very considerable 
difficulties exist in the formation of a perfect scientific arrangement of the birds of the British Islands, since 
these are but an appendage of a vast tract embracing the two continents of Europe and Asia, sections of the 
world assimilating in their bird-life, not only as regards genera, but in many instances also with respect to 
species. Hence in our own lists there will he occasionally breaks, as it were, that would be filled up by 
forms which, while found not far distant from us, still have never been actually killed in our islands. Far 
wider gaps will of necessity occur through the absence of such genera as are peculiar to Australia (the 
Bower-, Lyre-, and Mound-raising birds), or of those which are confined exclusively to the New World 
(Toucans, Trogons, Humming-birds, &c.). 
Man has frequently been induced to try his hand at the introduction of certain species the acquisition of 
which he has considered desirable ; such attempts have generally proved futile. Nature having adapted each 
for a certain locality, the climate and the condition of the country must be altered and rendered fit for 
the reception of either bird or quadruped before there is the slightest chance of their successful naturali- 
zation. Many persons have been desirous of establishing the North-American Prairie-Hen {Cupidonia cupido) 
