Wednesday, 29 August 2012

House of reed

Blundering around inside a reedbed is all in a normal day’s work for a Grumpy Ecologist, usually ending up thoroughly wet and ‘bloodied’ with reed-cuts.  The subtle variations of reed height and density, and the water depth, provide a guide to the location of the reedy constructions of some of the reedbed inhabitants.

Water Voles can be extremely common in wet reedbeds, with latrines and feeding stations every couple of metres.  One of the less frequently mentioned signs of Water Voles is the ‘Vole Mansion’ (above photo) but deep inside reedbeds these constructions can be very numerous.  The neat ball of woven reed strips is slung within a reed framework and under a loose reedy roof, the supporting reeds trimmed off with a typical Water Vole bite.  They are often provided with a reed ramp access down to an outside latrine.  The whole mansion is around 25 cm high and 20 cm in width.

The Water Rail nest is a neat cup, about 15 cm across, of woven reed.  Built just above water level, this one was in 35 cm of water depth and typically built just above water level.  Most Water Rail nests seem to have a covering reed ‘canopy’; this one (below) is open, however it was located in tall (240 cm) and dense reed (360 stems/m2).
Most Bittern nests also seem to be built just above water level with good, stout, reed stems bent over and folded in, before a woven platform around 40 cm in diameter is constructed on top.  A lining of finer material, other aquatic plants if present nearby, may be added.  One or two reed ramps lead down to the water.  The deepest water I have found a Bittern nest in is 115 cm.  The nest shown below is perched at an unusually high 110 cm on its scaffolding, above 62 cm of water, but remained above this spring’s rising water levels.  A scattering of downy feathers in and around the nest provides some pointers to the successful outcome.  She obviously had heard the weather forecast. 


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