THE SMALL MAMMALS OF ESSEX 39
Common Shrew (Sorex araneus Linn.) Map 1
Laver: "This animal occurs commonly in all parts of the
county, although it is more often heard than seen......Hedge
and coppice.....frequently resound with their faint but shrill
war-shrieks"
This is still a widely distributed and very common species.
It is by far the commonest species of bottled mammal but forms
a smaller proportion of the live-trapping captures. There are
two probable explanations for this: Common Shrews are a more
abundant species in rough grassland and hedgerows. The ex-
tensive trappings (Appendix 1) included more of these habitats
than the Coptfold study grids (Table 1). Other trappings at Copt-
fold, in hedgerow and field edge habitats revealed a somewhat
higher proportion of this species (5.8%). (Corke, Cowlin and Page
1969). The high trap mortality may have prevented a resident
population remaining on the main study areas. The bottles were
collected from just those habitats which the trapping results
indicate are the best shrew habitats. The second explanation is
that the traps are less sensitive to light-weight shrews than
to rodents. The traps were rarely adjusted to the finest tension as
it was not desired to catch and kill large numbers of shrews.
It is quite safe to say that this species is widespread and abun-
dant throughout Essex. Burton (1966) considered that the Com-
mon Shrew was likely to penetrate well into London, colonising
railway banks and waste ground. The results of our few trap-
pings in East London support this suggestion.
Pygmy Shrew (Sorex minutus Linn.) Map 2
Laver: "I find Sorex vulgaris (i.e. S. araneus) and Sorex
minutus equally common, either as captured specimens or lying
dead on paths in autumn."
The map shows that this species is widespread in Essex
although perhaps not extending so far into London as the Com-
mon Shrew. But the records do not agree with Laver's statement
that it is as common as the Common Shrew. The araneus/minu-
tus ratio is about 11/1 from the live-trapping, 14/1 from the
bottles and 3/1 from the owl pellets. The greater abundance
of S. araneus is confirmed in most parts of England (see Glue
1970 and Crowcroft 1957) and even at the turn of the century
Adams (1916) notes that the pygmy shrew is "never so plentiful
as the larger species". It seems unlikely that there has been
a change in their relative abundance in Essex since Laver's
time and so either Laver's impression or his ability to separate
the two species must he at fault. There is a tendency for ob-
servers to report any shrew seen as a 'pygmy' because they are
much smaller than mice; and so any unsupported record should
he regarded with suspicion. Bottle hunt records do not suffer from
the possibility of incorrect identification because the specimens
can be checked against material of known identity. There is a