PREFACE. 
Vll 
number of individuals prevailing in different parts of the island. 
The plants which appear on particular soils attract such land 
birds as feed upon their seeds. The submarine rocks and grounds 
on which sea- weeds grow plentifully so as to afford shelter to the 
minute fishes, and the molluscous and crustaceous animals on 
which the wading and swimming birds feed, tempt them in greater 
numbers to the neighbouring shores. The oozy, the sandy, the 
gravelly, the stony, the rocky beach, has each its favourite species, 
as has every peculiar natural or artificial feature of a country from 
the level of the sea to the most lofty mountain summit. 
The difference in climate between Ireland and Great Britain 
cannot be said to deprive the former island of any species found 
in the latter. The comparative mildness of winter in the more 
western island has, however, great influence on birds. Even in 
the north of Ireland, a few land species, considered as birds of 
passage in England, except in the extreme south, become resi- 
dent ; and some grallatorial birds remain throughout the winter, 
although found only in the south of England at this season. The 
soft-billed birds also being generally able to procure abundance of 
food, are by the comparatively high temperature, more inclined to 
song at this period of the year. The humidity of the climate, 
together with the great extent of bog throughout the island, 
brings hither to winter, different species of grallatorial and other 
birds, in much greater numbers than prevail in England or 
Scotland. The extent of moist and rich meadows in summer 
has a similar, but more limited, influence. The want of extensive 
districts of old timber seems, when fully considered, to have little 
effect in excluding from Ireland species which inhabit Great 
Britain. 
To the laws of geographical distribution alone must, I conceive, 
be attributed our want of species not affected by any of the 
