The Otter Lutra lutra in Essex 1996-2002
(28%) in 2000, six of 14 (43%) in 2001 and eight of 22 (36%) in 2002. Spot checks were made at
Walthamstow Reservoirs in 1997 and downstream to the confluence with the Thames in 2002 but no
evidence of Otters was found. The downstream limit to distribution on the Lea has consistently been
around Enfield Lock. The population appears to be centred on the complex of gravel pits in the Lea
Valley Country Park. The upper reaches of the Stort, which have some seemingly suitable chalk
stream habitat, do not appear to be utilized.
The index value (Fig. 10) peaked in 1998 and has subsequently declined.
Fig. 10. Otter population index values for the river catchments
1 70
Essex Naturalist (New Series) 20 (2003)