The Essex Naturalist
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46kHz and 55kHz and by DNA analysis (Barrett et al, 1997) Both species occur
in Essex and will be the subject of a future review.
Summer roosts have been found in most areas and the largest, at Maldon, has
held up to 1000 bats. In some years this has been the largest colony in England.
Winter records are fewer, although in January 1997 53 Pipistrelles were found
hibernating at Billericay and in January 1995 over 30 bats were found in window
frames at Goojerat Barracks, Colchester.
Nathusius's Pipistrelle Pipistrellus nathusii (Keyserling & Blasius, 1839)
This is a migratory species that has been recorded more frequently in Britain in
the last 15 years. (Speakman et al, 1991) Whether this reflects a genuine
increase or better observer coverage is uncertain. The only Essex record and the
third for mainland Britain is of an individual photographed at White Roding in
January 1985. The identification was made by Dr R.E. Stebbings.
Barbastelle Barbastella barbastellus (Schreber, 1774)
An extremely rare bat, both known British breeding colonies have been found
in Norfolk where the species favours old parkland and woodland, often within a
rivet valley (Goldsmith, 1997). This species was known to Victorian naturalists
around Epping and Laver saw them occasionally, identifiable in flight. More
recently, K. Burtsall (pers. comm.) captured one near Wendens Ambo in 1949
and in March 1969 one was found hibernating in the church porch at Bradwell.
The only record for the period is of an individual seen roosting in a stable block
at Spain's Hall, Finchingfield in August 1992.
Brown long-eared bat Plecotus auritus (L., 1758)