296 



SCIENCE-GOSSIP. 



THE MIGRATION OF BIRDS. 



{Continued from page 27S.; 

 Geographical. 



npHE Report treats the subject from the geo- 

 graphical point of view thus : 



" General. — In passing from their summer to then- 

 winter haunts, birds proceed from a northern to 

 a southern chme, and vice versa in the spring. It 

 does not at all follow, however, that these seasonal 

 haunts are reached by a single movement from 

 north to south, or the reverse. Each species or 

 individual of migratory bird has its particular 

 summer and winter resorts, and these do not 

 necessarily lie in the same meridian — indeed this is 

 often far from being the case. To attain these 

 particular seasonal habitats many of the voyagers 

 must depart more or less considerably from a direct 

 course. This is especially the case in western 

 Europe, v.here, owing to the south-v,-estern extension 

 of the land-masses, and the consequent irregularity 

 of the coast-line, various more or less devious 

 routes must be and are followed. The interposition 

 of the British Islands between the north-western 

 portion of the Continental area on the one hand 

 and Iceland and Greenland on the other is an 

 important additional factor in this deviation. . . . 



" The chief and most interesting movements from 

 the geographical standpoint are the intermigrations 

 between our islands and Europe. There are, 

 however, a number of movements between the 

 various sections of the British and Irish areas 

 which are of considerable importance. 



" Intermigration betzieen Britain and Norihern 

 Continental Europe. — Between Britain and Conti- 

 nental Europe travel a host of migrants which are 

 either birds of passage on, or winter visitors to, our 

 shores. The former \-isit our eastern coast-line in 

 spring when journej-ing to their northern summer 

 haunts lying to the north-east of Britain, and 

 again in autumn ^\•hen returning to their winter 

 quarters to the south of our islands. The ^\inter 

 \'isitors are chiefly individuals from the ranks of 

 certain species of the birds of passage which 

 winter in the British area and emigrate to the 

 north-east in the spring. 



"In the autumn these numerous migrants cross 

 the North Sea and arrive on the east shores of 

 Britain at points between the Shetland Isles and 

 the Humber or the northern seaboard of Norfolk. 

 All the movements do not necessarily cover this 

 extensive stretch of coast-Une, but such is not in- 

 frequently the case. Indeed, as a rule, they are 

 recorded from the greater part of the region 

 indicated. It is possible to define the southern 

 hmit on the coast at which these birds strike 

 Britain ^'.•ith a considerable degree of precision. 

 No section of the British coast is so well equipped 

 with light-stations as that which lies between the 

 north coast of Norfolk and Dungeness. In addition 

 to an average number of lighthouses there is a fleet 

 of Ughtships off the coast which are most favour- 

 ably situated for recording the movements of birds 

 crossing the North Sea to the Enghsh coast. These 

 lightships have furnished the Committee v.-ith some 

 of the most carefully kept records to be found 

 among the returns, and it is a very significant fact 

 that these great autumn immigrator\- movements 

 are not observed at these south-eastern lighthouses 

 and lightships, Evidence of a particularly impor- 



tant nature in this connection is also afforded by 

 the records kept at the Outer Dowsing Lightship, 

 the most isolated of the stations in the North Sea, 

 situated about thirty-eight miles east-south-east of 

 the mouth of the Humber. At this station these 

 important movements are not obser\-ed, another 

 significant fact, indicating unmistakably that these 

 migrants pass to the northward or westward of this 

 lightship. 



" The conclusion at which I have arrived, after a 

 long and careful study of the records, is that these 

 immigrants and emigrants from and to Northern 

 Europe pass and repass betvreen this portion of the 

 Continent and Britain by crossing the North Sea 

 in autumn in a south-v.-esterly direction, and in 

 spring in a north-easterly one, and that while the 

 limit to their flight in the north is the Shetland 

 Islands, that on the south extends to the coast 

 of Norfolk. (1) During these movements the more 

 southern portion of the east coast of England is 

 reached after the arrival of the immigrants on the 

 more northern portions. 



" It is to be remarked also, as bearing upon this 

 important point, that all the species occur on 

 migration in the Orkney and Shetland Islands, but 

 not in the Faeroes. And, further, all the British 

 birds of passage to Northern Europe are either 

 summer \-isitors to Scandina^■ia or are regular mi- 

 grants along the western shores of that peninsula. 



' ' After arri\-ing on our eastern shores, these 

 immigrants from the north — some of them after 

 resting for a while — move either down the east 

 coast, en route for more southern %sinter quarters, 

 or, if winter visitors, to their accustomed hatmts in 

 Britain and Ireland. A fe'w occur as birds of 

 passage on the west coast and in Ireland, which 

 they reach by overland routes across Britain, and 

 then pass southwards to their winter quarters. 

 The west coasts, however, do not receive directly any 

 immigrants from Continental Europe. 



"Intermigration bet-a-een the South-east Coast of 

 England and the Coast of Western Europe.—' East and 

 West Route.' — This is one of the discoveries of the 

 inquirj'. It has been already shown that the more 

 southern section of the east coast of England does 

 not receive immigrants direct from Northern Europe. 

 There is, however, a considerable amount of migra- 

 tion of a particular description, and on the part of 

 certain species, obser\-ed at the lightships and 

 lighthouses between the Kentish Coast and the 

 Wash. During the autumn, day after day, a 

 stream of migrants, often of great volume, is 

 observed off the coast, flo^\■ing chiefly from the 

 south-east to the north-west at the more northerly 

 stations, and from east to west at the southerly 

 ones, across the southernmost waters of the North 

 Sea. This will be hereafter mentioned as the 

 ' East and AVest Route.' From the stations off the 

 mouth of the Thames as a centre, the birds either 

 sweep up the east coast, sometimes to and beyond 

 the Tees fmany proceeding inland as they go), or 

 pass to the west along the southern shores of 



" (1) The formation adopted by the migrants during passage 

 would seem to be an extended Une — perhaps a series of lines 

 — whose right wing extends to the northern islands and its left 

 wing to the coast of Norfolk." 



