The Otter Lutra lutra in Essex 1996-2002
Results
The overall percentage of positive sites for Essex 1996-2002 (excluding the foot and mouth year
2001) is shown in Figure 2. During the 1996 survey of Essex, 234 sites were visited and 27% were
found to be positive for Otters. On this initial survey the animals were found in five regions - Hamford
Water, the catchments of the Stour and Colne, the short Essex length of the Cam and stretches at the
Lea/Stort confluence.
In 1997, 35% of 239 sites proved positive with new records for the River Blackwater. The following
year 241 sites were visited and 24% were positive with reduced numbers on the Stour, Hamford
Water, Colne and Blackwater. A slight increase in distribution was seen on the Chelmer but this
meant little in view of the apparent losses on the adjacent Blackwater. During the 1999 survey 28%
of 259 sites were positive but no signs were found on the River Colne or on Hamford Water. For the
first time, however, animals were located on the Roding with spraints found from above Ongar
down to Ilford, well within the London boundary. In 2000 the result was 31% with little evidence of
range expansion or population consolidation within Essex. The survey of 2001 was severely ham-
pered by lack of access to river banks due to foot and mouth disease and so the survey was extended
into 2002. In this final year 31% of sites were positive. Details of results from individual catchments
arc outlined below.
The distribution of positive sites in Essex for 1996 - 2002 is shown in Figures 3 - 9. Index values are
given in Figure 10.
Fig. 3. Distribution of Otters 1996
Essex Naturalist (New Series) 20 (2003)
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