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THE ESSEX NATURALIST.
counted in a flock. So far as I am aware these gatherings are
unique. The flocks are of purely local nature and are
probably the outcome of the conditions at the reservoirs. It
is fairly safe to say that these flocks are composed of native
birds. The chief cause of the unusual numbers of this species
is probably the security for roosting and nesting which is
found on the trees of the islands and in lesser degree to the
supply of food in the shape of dead birds and fish. It is not
surprising that its very close relative, the Hooded Crow, is a
very rare straggler, as this form is just as scarce in the south
of the County as the Carrion Crow is common. The two species
of Pipit have added to the interest of the avifauna. The
Meadow Pipit is not only a numerous winter resident, but it is
also a breeding species at the northern end of the area. I stated
in my History of the Birch of Essex that if the necessary attention
was given the Rock Pipit might be found to frequent the stone-
facings of the reservoirs. Several occurrences during winter
have since been reported. It is a new inland species for the
County. Of the three species of Wagtail, the Yellow is the only
one which calls for special comment. It has bred for at least
twenty-eight years, and is now much the more numerous of
the two breeding Wagtails. It is strongly represented from
Walthamstow to Enfield Wash. The Reed Warbler has a
very limited distribution inland in Essex, and it is of much
interest that a strong colony has been established at the more
southern reservoirs, and this interest is heightened by the fact
that all the nests have been found in bushes, such as privet
and elder. The Swallow, Martin and Sand-Martin are included
here mainly on account of the remarkable gatherings which
collect at the time of the autumn migration, and the Sand-
Martins have adopted the drain-pipes in the walls of the
aqueducts, as at the King George, for nesting purposes. The
Reed Bunting, Grey and Pied Wagtails, Sedge Warbler and
Wheatear, which complete the Passeres, do not call for special
comment. The three species, which are in each case the sole
representative of their particular order, each provide their own
interest. The Swift, like the Swallow and Martins, is seen
numerously at the time of emigration, but the series of early dates
of arrival of this species are its chief interest. In six different years
between 1922 and 1932 inclusive the Swift arrived on 18th (the