9
urbanisation. The main concentration is the
100 pairs present in the Fingringhoe area.
Loss of habitat has restricted Stonechats and
Whinchats to about 10 pairs each and the Red-
start is now mostly seen as a passage migrant
in Autumn.
Lastly, the decline of the Rook pre—dates Dutch
Elm Disease. In 1945 there was an estimated
total of 22,300 nests in Essex and 9,738 in
1975, mirroring a national decline of 43% in
the same period. The Rook feeds on grassland
invertebrates and the loss of grassland has
been the main reason for the reduction in
numbers.
Overall, many species of birds in Essex have
shown a change in status during the last 100
years. I am indebted to the "New Guide to the
Birds of Essex" for the statistics and hope
that sufficient of you will send it your
records so that future changes can be as
well-recorded as those of the past.
JOHN DOBSON
BLOODSUCKERS IN ESSEX (Part I)
There are four main groups of bloodsucking
flies native to Britain. The mosquitoes or
gnats (Culicidae), the biting midges (Cera-
topogonidae), the blackflies (Simuliidae)
and the horseflies (Tabanidae). On top of
these there are also three members of the
family Muscidae that bite.
.