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February bird sightings and marine wash-outs at Saltfleetby-Theddlethorpe NNR

Cliff Morrison

With most of the berries and fruit having been consumed in the dunes before the middle of the month, the saltmarshes, sea and shore provided greatest interest when we visited Saltfleetby-Theddlethorpe NNR in February.

Cold on-shore winds during the winter often result in ‘wash-outs’ of marine life living in the intertidal/sublittoral areas along the coast. There have been three such events occurring from 17th January, culminating in the largest following the mini ‘beast from the east’ from 2nd February onwards, where winds speeds measured from the dunes, ranged from 33mph on 2nd, up to 41mph on 8th and 33mph on 9th.

The first wash-out event was principally of bivalve razor clam shells (Ensis siquila), comprising both mature animals up to 20cm long and immatures just 3cm long. Many thousands were strewn along the beach, soon to be found by over 2000 gulls. The second event also included thousands of potato apples, a sea anemone, which like the razors, burrows into the sand. The ‘potato like’ shape of its whitish shell gives it its name, but when alive, it is covered in creamy coloured spines lying flat along the shell contours.

Mature razor clams. Image: Cliff Morrison
Mature razor clams. Image: Cliff Morrison
Potato apple sea urchin and immature razor clams. Image: Cliff Morrison
Potato apple sea urchin and immature razor clams. Image: Cliff Morrison

The last event proved to be by far the most devastating, with literally millions of razor clams washed up along the shore. Occasionally, white cuttle-bones, from the common cuttlefish can be seen along the strand line, but this time there were thousands, ranging in size from just a few cm to 25cm.

Millions razor clams in February wash-out. Image: Cliff Morrison
Millions razor clams in February wash-out. Image: Cliff Morrison

Vast beds of pale grey-brown hornwrack many hundreds of metres long and wide have also been washed up, being particularly dense along south of Crook Bank. This species might be thought to be a seaweed, but is in fact a bryazoan animal, which grows in plant-like clumps on the seabed where it filter feeds on plankton. It is able to gain purchase by growing on solid substrate on rocky shores, but on sandy shores is always vulnerable to strong wind and wave action.

Within the hornwrack, there have been many edible Dungeness crabs, some still alive, along with bright pink strawberry anemones, some up to 7cms in diameter, and starfish of a couple of species. Snow buntings have found rich pickings in these areas, with the resident wintering flock of up to 18 increasing to 23 birds. At least 2 foxes have also been feeding here during the daytime, but are vulnerable to dog disturbance, when they have to make a dash back to the dunes.

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Many strawberry sea urchins washed up in the vast carpets of hornwrack, which provides excellent feeding substrate for snow buntings. Images: Cliff Morrison.

The shore holds a roost site for up to 2000 black-headed and common gulls, which mainly feed inland during the day, whilst perhaps up to 150 herring gulls and 70 great black-backed gulls are to be seen during the day. However, during these was-outs, there have been well over 2000 herring gulls feeding on the wash-out bonanza, with both the common and black-headed gulls staying to feed as well. Not surprisingly an immature Iceland gull and a yellow-legged gull were reported on 11th February.

2 foxes have been out to the strand line feeding during the wash-out bonanza, but being far from the dune bushes have to dash back for protection when dogs are about. Cliff Morrison

2 foxes have been out to the strand line feeding during the wash-out bonanza, but being far from the dune bushes have to dash back for protection when dogs are about. Image: Cliff Morrison

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Herring gulls feeding on razor clams. Image: Cliff Morrison

A wintering flock of over 100 cormorants has fared very well, with birds feeding just offshore seeming to have a high catch rate of fish. There are also good numbers of sanderling and dunlin, with flocks of over 200 and 500 respectively.

Whilst the wash outs may have provided excellent feeding, many sea birds, such as guillemots, struggle to feed in the constant gales and rough seas. A beach survey along the 8kms of strand line on 11th yielded 5 razorbills, 3 guillemots, 1 kittiwake, 1 herring gull, 1 wigeon, 1 kestrel and 8 woodcocks. Fortunately, so far, this is a very small fraction of dead birds compared to the previous ‘beast from the east’.

Woodcocks arrive from Eastern Europe and Scandinavia from October, wintering in British woodlands and feeding nocturnally in meadows. However, cold weather movements can occur right through the winter and there was a large arrival from 3rd February, when over 20 birds could be seen in the dunes, even though they keep hidden during the day unless disturbed. Unfortunately, they are often weakened after a long sea flight and can be vulnerable to gulls when approaching the shore. One was seen to be taken by a peregrine as it crossed the tide line earlier in the year.

 

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