BROAD FEATURES OF ORNITHOLOGY OF ESSEX. 267
observed daily for over six weeks. There is some evidence to
show that some of these migrations actually reach the shores
of Essex, but much more evidence is needed to enable an opinion
to be formed of the extent of their influence on the avifauna
of the county.
The most definite information of migration has been gained
from ringing investigations. Up to September, 1939, at least
199 birds had been recovered which had been either ringed or
found in the county, sometimes both. Thirty-two species are
represented, and those which figure most prominently are
the Starling with 41, the Black-headed Gullwith 36, the Blackbird
with 21, the Common Gull with 14 and the Teal with 13 recoveries.
From these results valuable information of the movements of
the birds has been obtained.
There is one feature on which I touch briefly in conclusion.
The 149 unplaced birds are a heterogeneous group. Some,
such as the Lapland-Bunting and White's Thrush, are included
in the county list on the strength of one occurrence, while others,
such as the Pied Flycatcher and Ring-Ouzel, have occurred so
often as to be almost entitled to a place among the regular birds.
Irruptions, which occur periodically, are responsible for the
appearance of such birds as Crossbills, Waxwings and Pallas's
Sand-Grouse. In neighbouring counties we find such birds as
the Cirl-Bunting and Dartford-Warbler well established as
breeders, but it is rarely that they are found in Essex. The
Arctic-Skua passes the Norfolk coast every autumn, but it
has been recorded from Essex only on rare occasions. There
is something of interest about the occurrences of the last species
which I shall mention, the Avocet. It is likely that at one
time it bred as Dale, writing in 1730, stated that it was frequently
seen near Harwich, sometimes in summer. Otherwise this
species has been observed on four occasions only. Eight are
said to have been shot many years ago and nothing more was
seen of this bird until July, 1934, when two parties of five and
four respectively were seen along the Colne. Shooters wiped
out one party of five, and it was found that one of the birds
was ringed. It was ascertained that this bird had been marked
in the Rhone Delta in May of that year. This bird and probably
the others had flown almost due north from the Mediterranean.