138
THE ESSEX NATURALIST.
on October 2nd, 1903, states that Fowlness is a landing place
for a number of birds. In October of late years, in addition
to many other birds, large numbers of Crows and Rooks, accom-
panied by an abundance of Jackdaws, had arrived. The numbers
passing over in a day amounted to hundreds. On one occasion
the birds had to fly against a very strong north wind, and several
were seen to drop into the water only a few hundred yards from
land. On September 20th, 1914, a very large number of Martins
passed along the Essex coast from Shoeburyness to Westcliff,
flying due west. Many thousands are stated to have passed in
three hours. A similar migration was seen, although the numbers
were not estimated, on the Stour on September 22nd, 1924, when
many Martins passed to the west. A considerable movement
was noticed at Southend on October 31st, 1929, between 9 a.m.
and 3 p.m. Rooks were mostly in evidence, small parties
of from six to thirty having been seen. Small parties of Sky-
larks, a few Linnets, several parties of female Chaffinches, and
one party of seven Song-Thrushes were also observed. The birds
were coming across the estuary from the direction of the Kent
coast.
The last source of our knowledge, that which has been derived
from ringing investigations, remains to be explored. One
hundred and forty-seven birds have been recovered, which were
either ringed or found in the county, in some cases both. Twenty-
eight species are represented, the Starling leading the way with
31 recoveries, closely followed by the Black-headed Gull with 28.
The only other species to reach double figures are the Blackbird
with 18 and the Common Gull with 14 recoveries. An analysis
of these ringing recoveries demonstrates above all how complex
are the movements of birds and that a great amount of data is
necessary before definite conclusions may be formed. I have
prepared a table (D) to illustrate the types of seasonal migration.
The year is divided into summer and winter, the first running
from April 1st to August 30th, and the second covering the
remainder of the year. No fewer than 16 different combinations
have been revealed. I have grouped these under three broader
titles, recoveries suggesting residence of some nature, those
suggesting migration and those which come under the head of
abmigration, which term calls for explanation. It has been
assumed that birds return to where they were born for nesting