Introduction Vil. 
The seabirds form a large group amongst periodical migrants, 
moving directly south in autumn, to return with astonishing 
regularity to their northern nesting quarters in spring. These 
ocean wanderers on both migrations rarely move within dis- 
tances permitting observations from the sea coast, the nearest 
approach to their route-lines being Flamborough Head, so that 
these seasonal movements rarely come within the practical 
field of inland observers. Fortunately Mr. Matthew Bailey of 
Flamborough has collected, during a long course of years from 
his observation on sea, and the reports of fishermen, much valu- 
able information, which I have found of much use. The autumn 
migration of sea fowl appears to correlate with another equally 
remarkable movement—the presence of enormous shoals of fish 
on the coast, such as mackerel, herrings and sprats. In October 
seabirds of many sorts are closely congregated over large areas 
of the North Sea, to the east, the north, and south of the Head- 
land—and these massed thousands are made up of the rarer as 
well as more common species. There are the great, the sooty, 
and the Manx shearwaters, hundreds of skuas and gannets, 
cormorants, many sorts of gull, including the lesser gull and the 
rarer Arctic sorts, terns innumerable, guillemot, razorbills and 
puffin, and thousands on thousands of kittiwake, the latter, as 
Mr. Bailey says, feeding greedily at early morning and so gorged 
that the herring tails are hanging from their bills. 
Recent observations have taught us much we did not know 
before in connection with the movements of land birds; there is 
yet a large and important field left practically untouched on the 
broad water of the North Sea. 
It must be expected that a list, such as the present, must 
to a considerable extent be a compilation, the previous work 
of many naturalists and observers connected with the district. 
Messrs. William Eagle Clarke and Wm. Denison Roebuck, in their 
excellent ‘‘Handbook of Yorkshire Vertebrata,’’ 1881, have 
already dealt with the Yorkshire portion of the Humber district, 
but in eighteen years there have been many fresh occurrences 
requiring tabulating, and several new species added, more par- 
