56
The Essex Naturalist
This is the second most common bat in Essex and summer roosts are usually
found in older buildings with adjacent woodland. Flight is slow and fluttering
and insect prey is often gleaned from foliage. Larger prey items such as
nymphalid butterflies or noctuid moths are taken to a feeding perch and
evidence such as insect wings and bat droppings can be found in porches, barns
and other outbuildings. In the past, this species has been vulnerable to
chemicals used in remedial timber treatment, but safer, less toxic alternatives are
now invariably used. The monitoring of attics where these newer chemicals
have been used (Dobson, 1996) has shown that bats successfully return and
breed, often in the summer following treatment. The largest colonies to date,
from Gosfield and Frating have numbered 25-30 bats.
Occasionally, hibernating bats have been found, most notably, up to 16 in
converted bunkers near Coggeshall. The peak count from the Grays deneholes is
of five bats and individuals are sometimes seen in an ice-house at Great Braxted.
Discussion
The status of several species of bat in Essex has changed since Laver wrote his
review and is recorded in Table 1.
Table 1. Status of bats found in Essex at end of the 19th and 20th centuries
Of Whiskered bats he wrote that "I have no difficulty in finding all I have
required for the purposes of study" yet today it is apparently, a rare species. It is
occasionally found in Hertfordshire (P. Briggs pers. comm.) and small numbers
are found hibernating in deneholes in Kent and also in Westerham mines.
(Heathcote & Heathcote, 1994).