Monday, 8 September 2014

Holl-utopia - a year on



Towards the end of last year, I reported on a new wetland being created at Hollesley in Suffolk and given the name ‘Holl-utopia’ after the Dutch site Utopia Farm that inspired it.  At Hollesley Marshes there were very few breeding and passage waders and the site sustained only two pairs of breeding Lapwing annually. This fell well short of the aspirations and targets for the reserve. The issues revolved around the layout of the field system and the inability to raise water levels high enough.  The plan was to create a new 13ha coastal wetland habitat following the design of ‘Utopia’ on the island of Texel.  However, the wetland would be freshwater rather than the brackish conditions of the Dutch site, at least in the short term, due to the difficulty of constructing a sluice through the sea wall.
The key feature of Holl-utopia is that it is a shallow wetland with a high percentage of islands; some grassy, some bare, some covered in sand or gravel.  The landform creates extensive terraced areas of shallow water down to just 20cm depth, with a slightly deeper central ditch system.  Water levels will drop during the spring and summer to expose extensive muddy areas and ultimately dry out to just retain water in the deeper ditch features. The drying out is seen as an essential feature for rejuvenating the wetland in the future.   New water control structures allow water to both enter from, and drain to, the adjacent existing ditch system.  An electric anti-predator fence around the margins of the wetland keep the local foxes as mere spectators. 

The first spring saw Glossy Ibis, Spoonbill, Temminck’s Stint and Garganey recorded, along with 25 species of wader.  So how did the first breeding season shape up (with thanks to Dave Fairhurst for the data)?  Not too bad:

·          Shoveler - 1 female seen with 7 ducklings.
Lapwing - 25 nests fledged 60 young with 100% hatching success.
Ringed plover - 3 pairs fledged 9 young.
Little Ringed Plover – a male was on territory throughout May
 Avocet – 41 pairs fledged 82 young, the largest number of young fledged from a single site in       Suffolk since 1986.
 Oystercatcher – 1 pair fledged 2 young
Redshank – 10 pairs fledged 30 young.
Black headed gull – 1 pair fledged 3 young.
Shelduck – 1 pair fledged 7 young.

     
     Pics above: Hollutopia in May and July


7 comments:

Paul Tout said...

What is the "slightly deeper ditch system" for? Can fish oversummer in it? Do you want them to? If the answer to these questions is a) fish and b) yes then I wouldn't do that if I were you....

Grumpy Ecologist said...

Totally agree. I looked at the nearly dry ditches earlier - full of small 3-spined sticklebacks and palaemonetes shrimps. The ditches should dry completely most years.

Paul Tout said...

I have this row at Isola della Cona (NE Italy): When it was contructed deep ditches were constructed that allow pike and carp to oversummer. Totally counterproductive if you ask me but there you go. The only positive aspect at present is that the ditches are slowly filling with sediments stirred by horses and greylags, are gradually disappearing and are unlikely to be restored.
All looking a bit tired productivity-wise. Need to try something to liven up the show. Dytiscus larvae (loads) seem particularly destructive of potential food sources for birds. They seem to spend literally all day eating something or other.

Grumpy Ecologist said...

Depends what you are managing for doesn't it? In reed beds where we are managing for fish eating birds, deep refuges are sensible but in coastal systems that are best invert dominated we want to kill off any fish when we dry the site off.

Chris McGregor said...

Are these ditches anti-predator features?

Chris McGregor said...

Do the ditches have any kind of anti-predator function?

Grumpy Ecologist said...

Hi Chris, no the ditches all but dry up. The surrounding stock fencing is electrified to keep out larger ground predators such as foxes.