Newarp L.V., March 17th to April 15th, Crows on six days to W.
Leman and Ower L.V., Feb. 18th to May 8th, Skylarks, Starlings, Titlarks, Goldcrests, E. and E.S.E. to N.W.
Cockle L.V., Feb. 22nd to March 31st, Black Crows, Ducks, Jackdaws, Starlings, Larks, Lapwings, "Snow-birds" to W. On March 20th, 24th, and 26th, Black Crows or Rooks continuous from 5.50 a.m. to 11 a.m., E. to W.; and on 31st also continuous from morning to night in the same direction.
All these entries show a great immigration to our coast from the east in the spring months, and on precisely the same lines and directions as are travelled by these birds in the autumn.
An interesting feature of the autumn migration is the occurrence of a flight of the Blue-throated Warbler, Cyanecula suecica; twelve altogether were obtained, all being birds of the year, and nine of these on the coast of Norfolk, besides about twenty others seen by competent observers.
Very few Goldcrests, compared with the enormous flights of the previous autumn, have crossed, and the same scarcity is observable in the Heligoland return. Curiously enough, the Hedgesparrow, Accentor modularis, which migrated in such immense numbers in the same autumn, has been almost entirely absent. About half a dozen are recorded at Heligoland, none on the East Coast of England.
The intermittent migration of some birds, as the Jay, Shore Lark, Goldcrest, Hedgesparrow, Siskin, and Mealy Redpole, indicated by their extraordinary abundance in some years, and partial or entire absence in others, is perhaps suggestive of local causes influencing and regulating their movements, such as a succession of favourable breeding seasons, scarcity or failure of food, sudden meteorological changes; these acting separately or in combination, would be sufficient to compel the migration of large bodies of birds from centres or localities, where, under normal conditions, they would either have remained or some part only migrated. In this manner whole districts may become denuded for a time of their feathered inhabitants, and the balance become again rectified by a return movement in the spring, or from the surplus supply bred in other districts.
Of the enormous immigration which crosses our east coast in the autumn, either to winter in these islands or passing across them, a small proportion only appear to return by the same route. Spring returns from lighthouses and light-vessels show birds then move on the same lines as were followed in the autumn, but in the reverse direction. Yet these return travellers do not represent anything like a tithe of the immigrants which, week by week and month after month in the autumn, pour in one great tide on to the coast.
What is called the "first flight" of the Woodcock arrived on the Yorkshire, Lincolnshire, and Norfolk coasts on the night of Oct. 21st. The "great flight" or rush, which covered the whole of the east coast from the Farn Islands to Yarmouth, was on the nights of the 28th and 29th. These two periods correlate with the great flights of Woodcocks over Heligoland.
We are again indebted to Professor Ch. F. Lütken, of Copenhagen, for a list of the birds killed or taken alive against the lantern of the Stevns lighthouse, at the entrance of the Oresund, in Zealand. The list is specially interesting, as it names so many of the Heligoland birds. The occurrence of Locustella fluviatilis on Sept. 5th is the first recorded example for Denmark.