"Why are the water levels so low?" "Why are the water levels so high?" These are questions you always get asked when working on a wetland. Currently the water levels on the fresh marsh are low. Why?
We have target water levels for each month/season, in each area of the reserve - brackish marsh, fresh marsh and reedbed. These are designed to provide optimal conditions for the most important wildlife at any given time. For example in the spring we keep all the levels higher to isolate the islands from ground predators. This allows the ground nesting species like avocet and ducks to have a greater breeding success.
At this time of year we drop the water levels to expose wet mud for the birds that are using the reserve like a motorway service station. These species known collectively as passage migrants are passing through the UK on long journeys from their Arctic breeding grounds to wintering areas (usually) in Africa. It is these species which attract a lot of our human visitors. The wading birds can only find food in wet mud so to keep the food available we send pulses of water through the fresh marsh to keep re-wetting the surface of the mud. This means you may visit on a Monday and see hardly any water but come on the Wednesday and it will be wet again. As with most things this whole issue is complicated by the weather. Both wind and rain can have an effect. The wind can be the most strange. If the direction changes whilst you are watching birds on the fresh marsh it can sometimes appear like a tidal effect as the very shallow water volumes are moved about the lagoon by the wind.
This August levels are slightly lower than usual. We have had to totally drain the brackish marsh to allow for construction of the new seawall. In the fresh marsh we also needed to keep the Parrinder line as dry as possible but we have been able to keep a pulse of water going through the marsh. As you can see from this picture taken today, from Island hide, the birds seem to like it! I hope you do to.
Dunlin from the new Island hide. These birds formed part of a 200 strong flock, later joined by a little stint .