Ixii LINES OF MIGRATION. 



and southern races of the same species reach lis. We have large 

 and small Wheatears^ Crossbills, Ring- Plovers, Dunlins, &c., which 

 no doubt come to us from different countries, as it is well known 

 that birds of wide distribution are subject to great variation of form. 

 Messrs. John Cordeaux, Harvie-Brown, and W. Eagle Clarice 

 have done much to increase our knowledge in this field of research. 

 It is now plainly seen that Land-Birds avoid high lands and moun- 

 tainous regions when migrating, and adhere year after year to 

 well-defined routes, entering certain openings of the coasts, and 

 generally following river-valleys when passing over land, but, when 

 deep inlets or bays occur in their course, boldly crossing the sea 

 from point to point rather than following the indentations of the 

 coast-line. 



It has also been clearly shown that the following are the main 

 lines of migration : — 



1 . A stream of birds flows from east to west across England, having 

 entered the estuary of "■ the Wash " after crossing the 

 German Ocean from south-east and north-east (two streams 

 flowing almost at right angles to each other), and following 

 the river-systems of the Nene and Welland into the central 

 plain of England continues along the line of the Avon, and 

 down the estuary of the Severn to the Bristol Channel. 

 Some birds cross the Humber and come down the valley of 

 the Trent through Nottinghamshire to the Welland. Avoiding 

 the mountainous country of Wales, this living stream skirts 

 the Pembroke coast, and, striking across St. George's Channel, 

 reaches the Irish coast at Wexford to spread over the cen- 

 tral ])lain of Ireland. 

 a. A branch from this stream diverges to the S.AV. and enters 

 Somerset by Bridgwater Bay, crossing the Bridgwater flats, 

 and, keeping between the Quantocks and Blackdown 

 Hills, passes down the valleys of the Culm, Exe, and Otter, 

 partly spreading to the south-east and partly sweejung 

 round the south of Dartmoor to the South Hams of Devon. 

 By this route we believe the bulk of the Redwings, Field- 

 fares, Mistle-Thrushes, Song-Thrushes, Golden -crested 

 Wrens, Greenfinches, ChaflSnches, Linnets, Redpolls, Sis- 

 kins, Starlings, Sky-Larks, Long- and Short-eared Owls, 

 Lapwings, Water-Rails, &c. reach the south and east of 



