SEA-BIRD NUMBERS AND MAN 87 



in the 1930's, and, within the last few years, to south-east England. 

 These new colonies are not yet well-established, but at least there is 

 a tendency to recovery in a species which once appeared to be declining 

 to extinction. Unfortunately the Caspian tern has not yet returned 

 to the German North Sea coast where it became extinct some time 

 during the first World War. In both Britain and the United States 

 both the common and arctic terns have suffered a good deal from 

 egging, mainly in the nineteenth century and both World Wars, and 

 from the plume trade, though only perhaps slightly from this in Britain. 

 Undoubtedly both have had a general recovery in the present century, 

 though with marked fluctuations. It is doubtful whether, in any 

 year in the present century, there have been many more than seven 

 thousand common terns' nests occupied in England and Wales, and 

 likely that over half of these have been in Norfolk, where a great 

 recovery immediately followed the institution of the coastal sanctu- 

 aries in 1920. However, the colony on the Isle of May in the Firth 

 of Forth had, in 1936, nearly as many nests as all the Norfolk sanctu- 

 aries put together — about 3,400 against 3,618. There is an even larger 

 colony in Strangford Lough in County Down in Ireland, and the 

 common terns' nests in the whole of this very suitable county may 

 occasionally amount to ten thousand. 



The arctic tern does not appear to have increased in England and 

 Wales, as has the common tern, though there is no evidence that it has 

 decreased. This is probably because England is at the southern limit 

 of its world breeding-range, and the limit itself may be moving 

 gradually northwards, as is the case with many arctic and subarctic 

 species, owing to the present climatic amelioration. Certainly of late 

 the arctic tern has become very desultory at its colonies in the Scilly 

 Isles. It is doubtful whether, in the present century, more than three 

 thousand of its nests have been occupied in England and Wales, 

 and likely that more than half of these have been on the Fame Islands. 

 In the rest of Britain it outbreeds the common tern in most parts of 

 Scotland and the exposed part of Ireland. 



The roseate tern has made a fine recovery in the British Isles, 

 where the species was first discovered, in 181 2, and which now con- 

 stitutes its European headquarters ; its extraordinary breeding distribu- 

 tion appears to be of a relict type (Fig. 16, p. 90). The tendency of such 

 distributions is, of course, to become further restricted. However, the 

 trend has been reversed in Britain. It is doubtful if there were a 

 hundred nests or eight colonies in the whole of Britain in any 



