44
THE ESSEX NATURALIST
although others have informed me that they have been found
more abundantly in such situations."
The impression given by Laver is that this species was
widely distributed up to 1898, although never abundant since he
remarks that "their numbers are so small, they never can do
much damage".
Barrett-Hamilton (1910-21) records on Laver's authority that
the distribution of the Harvest Mouse in Essex is extraordinary
since these mice are much more rare to the east of Colchester
than to the west, and that they were frequent only until about
1900. No evidence was given to support this last statement and
there is no obvious reason as to why this animal should have
declined in abundance by 1910. It is normal for Harvest Mice to
be common in an area for a few years and then to disappear
locally, and probably such a local disappearance led to Laver's
unjustified belief that the species had become rarer throughout
the county.
It is of interest that none of the early naturalists made any
reference to Harvest Mice being found anywhere but in corn ricks
or in cereal fields at harvest time. This point was raised by
Arthur Thompson (1931), who at that time lived in Coggeshall.
He writes "I doubt whether any naturalist has found out how to
obtain it (i.e. the Harvest Mouse) except from stacks .... The
great mystery of these mice is what is their normal existence.
Some live in corn fields, where they build nests in growing corn
and spend the winter time in stacks, but even with these there is
uncertainty. A stack may have hundreds, and then no more will
be seen in the district for years, then the mice will begin to swarm
again . . . . I think some live in coarse herbage, feeding on
various wild seeds and on the insect life that abounds in such
places". These observations are of great interest, since they
contain the first reference to 'swarms' of Harvest Mice, which will
be discussed later, and also the first reference to Harvest Mice
inhabiting coarse herbage, which is now considered to be their
typical habitat.
In 1932 Thompson wrote that the previous December and
January he obtained 11 of these mice in Essex from bean cocks
standing in open fields. He also reports that there was a hedge
near his (Coggeshall) home where there were six Harvest Mouse
nests within 50 yards, and that several more nests were in course
of construction in the same area.
It appears that cereal ricks were an important habitat for
overwintering Harvest Mice. It has been said that oat-ricks were
favoured (Laver 1898) but Rowe and Taylor (1964) found that
Harvest Mice were as abundant in the wheat ricks that they
examined as in the oat and barley ricks. Rowe (1961) found one
dead and 16 live Harvest Mice during the threshing of a wheat-
rick at West Bergholt in December 1958. It is likely that the
majority of Harvest Mice inhabiting corn-ricks were carried to