Page:The Migration of Birds - Thomas A Coward - 1912.pdf/52

36 to a lesser extent the south-east coasts of Britain?

Coasting undoubtedly exists; birds, day migrants especially, may be observed following coastlines in steady flight, though a mile or less inland no passage is visible. On the North Norfolk coast I have seen little parties of swallows passing along the shore in spring, coasting slowly but steadily from east to west. All day long and almost every day for more than a week this steady flight was continued, though I never saw any passing within sight more than a few yards out at sea, nor any at all more than a few hundred yards inland. Evidence which cannot be refuted shows that this habit of coasting is general, though a deeply indented bay, an estuary or strait, is usually crossed, and by no means always at the narrowest point. The same careful observations prove that both narrow and wide river valleys are followed by migrating birds in greater numbers than are ever observed passing beyond the limits of these valleys.

Seebohm's experience in Siberia led him to doubt the existence of routes, but his later studies of migration in autumn at Arcachon and in spring at Biarritz, caused him to modify his ideas. He found a gentle but continuous stream of migrants following the coast of the Bay of Biscay, arriving from over the Pyrenees on their northward journey,