34
THE ESSEX NATURALIST
results of this work will be published elsewhere. A preliminary
report has already appeared (Corke 1970).
Bottle-hunting. Morris and Harper (1965) showed that it was a
common occurrence for small mammals to enter discarded
bottles, become trapped and die. One of the first reports of a
bottled mammal came from Essex (Burton 1963) and Essex holds
the record for the most individuals caught in one bottle (28 in a
quart milk bottle found by Morris).
A few of the records in the present survey have resulted
from casual collecting of bottled mammals; but systematic
searches by groups of Essex Field Club members or zoology
students, who combed the hedges and ditches of a wide area of
Essex, on particular days, has been the most fruitful method.
The skulls and mandibles of the collected mammals are easily
identified using the published keys (Corbet 1964, Southern
1964, Morris 1970). While a new 'bottle-hunter' was being
trained the identifications were checked by an experienced
worker. Apodemus remains are difficult to identify specifically
Using Fielding's (1966) method it was possible to identify 44 of
the 46 Apodemus skulls from the 1968 collection. All others
remain grouped as Apodemus spp and are excluded from the
maps. The results of the five bottle-hunts are summarized in
Table 2.
Table 2 
Summary of five 'bottle-hunt' small mammal collections from Essex.
N.B.—Only in 1968 were the Apodemus remains identified to species;
of the 46 Apodemus skulls 43 were A. sylvaticus. 1 A. flavicollis and 2
indeterminate.
Owl Pellets. Birds of prey regurgitate the indigestible remains
of their prey. The mammal remains can be identified using the
same techniques as for bottle-hunting. The review by Glue
(1970) shows how useful this technique can be to mammalogists
and it is unfortunate that it has not been more widely used in
the Essex survey. However, D. Hunford has made available
the results of several very useful analyses of owl pellets of which
many were collected on Foulness Island. These results are sum-
marised in Table 3.