Emma Rance, Marine Conservation Officer for Dorset Wildlife Trust, tells us why Holes Bay Nature Park is a top spot for wintering birds in Poole Harbour
You’d be forgiven for overlooking Holes Bay saltmarsh and mud flats as you travel upon Poole’s busiest bypass. The oozing mud may not be the most desirable place to dip your toe but these habitats are teeming with life. Beneath the surface of mud, silt, sands and algal mats sits a wealth of perfectly adapted fauna capable of surviving the silty, sometimes dark waters.
Holes Bay is home to internationally designated salt meadows, coastal saltmarsh, intertidal mudflats and reedbeds providing shelter, roosting and food for highly prized and protected wildfowl and waders. These include avocet, black-tailed godwit, common tern, shelduck and lapwing. Many of these favour the Overwintering Bird Sensitive Area, north of the railway embankment, as an important roosting and feeding site.
Photo 1: Lapwing by Lynne Newton
Research has shown Holes Bay to attract the highest number of bird species in Poole Harbour and the invertebrate worms, snails and hinged bivalves of the intertidal saltmarshes and mudflats provide a rich food source. To the enjoyment of avocet and shelduck, the ragworm is well suited to Holes Bay with a capability of surviving varying salinities atypical in estuaries. Normally orange-brown, males turn an iridescent blue-green during spawning and are known to reach lengths of over 1m! It has several feeding methods - powerful pincer-like jaws, suspension feeding or creating a mucous net to entrap surface prey before pulling them into its burrow.
Photo 2: Alitta virens or King Ragworm by A Semonov
The burrowing bivalve molluscs, cockles and clams, are favoured by the long-beaked spoonbills and black-tailed godwits whereas Mediterranean gull and little egrets prefer crustaceans such as crabs, shrimps and amphipods.
Photo 3: Manila clams by E Rance
Deeper still, the beautiful peacock worm, with its self-built sediment tube, twists open its radial feathery feet to feed on passing plankton - yet soon retracts to the safety of its burrow in times of danger. Dense beds of these beautiful segmented worms can take many years to form and create a refuge for sponges, sea squirts and seaweeds.
Photo 4: Peacock worms in Poole Harbour by P Tinsley
Holes Bay is a nursery area for juvenile fin fish too. European eel, bass, sprat, flounder, sole, grey mullet, sand smelt and herring all seek out refuge in the shallow depths.
The submerged dock walls and stable rocks of the Backwater Channel are inhabited by the nationally rare and protected sea sponge Suberites massa, and the flat oyster. An unlikely find in a busy shipping channel!
So, next time you visit the shoreline of Holes Bay think about its mud-appeal and what lies beneath. Learn more about Poole Harbour in our bird watching and natural history events. For more information about these events, click here: www.dorsetwildlifetrust.org.uk/events.html
Holes Bay Nature Park is part of The Great Heath Living Landscape.
To find out more about Holes Bay, visit: www.dorsetwildlifetrust.org.uk/Holes_Bay_Nature_Park.html
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