Tewinbury has been a HMWT reserve for many years. There is no access to the reserve itself but the new double storey hide affords superb views across the lagoon, channels and reed beds. A couple of years ago I videoed Water Voles from the old hide at a range of about 8-10 feet.The site lies in the Mimram valley, and contains a variety of habitats including wet meadow, tall fen / swamp, alder carr, willow scrub, willow pollards and chalk stream. The tall fen/ swamp occurs around a lagoon (overlooked by the hide) and along adjacent channels, and has a mixture of common reed, reed sweet-grass and common reed-mace. Willow scrub has been slowly invading the lagoon, but has been kept under control by Trusts staff and volunteers.
During 2006 and 2007 considerable work has been undertaken to make the swamp much wetter by removing silt build up and raising water levels. This work, combined with the removal or pollarding of willows, encourages recolonisation by common reed.
Wetland plants associated with the swamp include hemp agrimony, common comfrey, reed canary grass, water figwort, brooklime, water forget-me-not, marsh marigold, hairy willowherb, lesser celandine, yellow flag, purple loostrife, ragged robin and wild angelica. The surrounding banks support great horsetail, butterbur and town hall clock. There remain remnant tussocks of greater tussock sedge, a species now uncommon in Herts.
The swamp area is important for both wintering and breeding birds. In winter, reed buntings, yellowhammer and pied wagtail form night-time roosts in the swamp and carr. Breeding species include reed bunting, reed warbler, sedge warbler and occasionally grasshopper warbler. Mallard, coot, and moorhen also breed. Other species of note include kingfisher, water rail, snipe and woodcock. The site is also a passage stop-over for migrating warblers and other wetland birds.
The wet meadows vary in composition with the soils. Species here include meadowsweet, cuckooflower, greater birds-foot-trefoil, marsh horsetail, marsh thistle, skullcap and monkey flower. Marsh pennywort and southern marsh orchid, both uncommon in Herts, can be found. The alder carr woodlands around the meadows have notable species opposite-leaved golden saxifrage and remote sedge. Flocks of siskins and redpolls feed in the woodland during winter.
The River Mimram is a valuable chalk stream with a rich aquatic flora and fauna. River water-crowfoot, water starworts, water cress and lesser and greater pond sedge. Many different aquatic invertebrates have been recorded. Brown trout, water vole and otter can all be found within the stream. Other species recorded include 3 shrew species, harvest mice and 5 species of bat.The hide is situated at TL265139 along the entrance track to Tewinbury Farm Hotel. You are allowed to park in any of the designated car park areas. UNDER NO CIRCUMSTANCE PARK ALONG THE ENTRANCE TRACK. (Alan Reynolds)