Winter days working on the dunes

Holkham's nationally important sand dunes sandwiched between pinewood and beach

One of my favourite parts of the reserve has always been the sand dunes. Not only are the views special; the panorama from what little height we have on the reserve of sea, sand, pine woods and marshes can all be best appreciated here under the vastness of Norfolk’s towering and ever changing skies. Sometimes it might seem an empty harsh environment at the mercy of any weather that the North Sea might bring us yet the dunes hold a fantastic array of specialised flora and fauna in a habitat that nationally is constantly under pressure. For insects and birds that migrate or are blown off course from the continent it is the dunes where they usually first appear, the front line of land and there is no telling what might be seen. It all adds to the mystique of the place.

A male Stonechat, this striking looking relative of the Robin now nests on the dunes and if mild weather prevails will remain all winter.

In some parts of the UK sand dunes have been lost to unsympathetic holiday developments and golf courses which make places such as Holkham so valuable. In the summer the dunes really come into their own; we have one of the country’s best populations of Natterjack Toads favouring small sandy bottomed pools in the low lying ‘slacks’ to breed. With patience they can also be seen as they hunt for invertebrates across the open dunes. As many as five species of orchid can be found alongside a tremendous variety of insects and spiders. The list of the dunes' flora and fauna is long and constantly being added to. Birds love the dunes too; the limited scrub provides shelter for nest sites like Stonechats, Whitethroats, Linnets, Wrens and Dunnocks and is also a haven for newly arrived migrants in the spring and autumn. For that overall attraction to remain we do have to carry out regular and constant management work in the winter months which really brings us to the subject of this blog.

Removing bramble scrub from around a Natterjack pool. The toads like short turf around the pools in which to forage for food. In removing the bramble we also exposed an old WW2 gun emplacement.

Holkham’s dune system is part of the ever dynamic and constantly changing coastline of north Norfolk. In the very distant past they were formed from off shore accumulations of tidal debris and shingle, where marram and couch grass was able to take root and grow over a long period to form the dunes we have today. This process can take a very long time as successive periods of storms can erode and break down dunes before they truly establish although alternatively some spots form quite quickly. Take a look out in Holkham Bay today and you can still see this very process continuing. On the older dunes the current pine wood was planted back in the late 1800s. This was to prevent sand blowing across from the beach onto reclaimed arable fields and to stabilize the dunes as the first line of defence in flood and storm conditions. So whilst close on three miles of pinewoods made a new habitat, we now know that what remain as tree-free dunes are ecologically very important and this is where problems start to arise and our work starts and will continue so that the dunes' value remains intact.

Taking out pine trees to expose more of the original sand dunes

An area of cleared sand dune

One of the major problems we face is encroachment of the wood out onto the adjacent dunes. Pine trees widely disperse seeds and from these young trees soon form and left unchecked, the present day dunes would soon revert to woodland. Holm Oak is also problematic. This evergreen also readily takes root in sand and would soon really take over. These are even worse for us than pines as when they mature they cast such a heavy shadow allowing very little else to grow. Unlike pines there are also very few native inhabitants that live within them; be they birds or insects. Usually throughout the winter months we undertake management work that involves the aid of a happy and growing bunch of volunteers. With their help we try to clear areas of both pine and Holm Oak to either prevent their spread or sometimes remove established trees to reinstate the open dune habitat. 

Volunteers and staff feeding the fire

Another plant we remove is the berry bearing shrub Sea Buckthorn. It too has limited value to our native wildlife and soon takes over great swathes of dune if left unchecked. Again thanks to a grand effort from both volunteers and staff alike, we have managed to clear significant areas in the last few years. Whilst we are almost ready to conclude this year’s work it will still be very much ongoing in the future so if you fancy helping out in any of our tasks, don’t hesitate to contact us at s.henderson@holkham.co.uk for more details. Not only will you be helping us with a very worthwhile project but you might also see some of our special wildlife. In recent weeks we have managed to see a very rare wintering Dartford Warbler (it had only been seen four times previously on the reserve!), plenty of Stonechats, lots of special fungi including the nationally rare Tiny Earthstar, a scarce species of spider Agroeca proxima, sometimes known as the Fairy Lamp Spider (named after the lantern – like shape of its maternal egg sac which it attaches to a grass stem and then covers in soil particles) and a tiny insect the Pine-cone Bug new for the reserve!

The Pine-cone Bug, a new species for the reserve

Agroeca proxima, the Fairy Lamp Spider

Andy Bloomfield

Warden

The arrival of a new English goose ?

Pink-footed Geese flock over the marshes at Lady Anne's Drive

Ever since the days of the Victorian ‘gentleman gunners’, the wildfowlers and collectors of the distant past, Holkham has maintained its place as being one of the most consistent spots in the UK for attracting large numbers of wild geese. It was only during and after the Second World War with disturbance from heavy artillery fire that the vast skeins of Pink-footed Geese, the species that Holkham became synonymous with, temporarily deserted us. Holkham fits nicely into the ornithological history books not only for having one of the largest concentrations of ‘Pinkfeet’ in Norfolk when some 90,000 were estimated to be present on a single day back in 2006 but also for providing the county with its very first example. Pink-footed Geese, with their pink legs and feet are very similar to Bean Geese (with their orange legs and feet) and in Victorian times they were deemed one and the same. It took until 1833 before it was realised that two species were actually involved and how fitting it was that the first Norfolk Pinkfoot should be shot at Holkham. Incidentally that very first one was preserved and is still on display within Holkham Hall. This year Pinkfeet numbers have only managed to reach 33,000 on the reserve, still a significant total but far less than the 2006 count! Reasons for such a drop include less sugar beet being grown locally (the harvested yet unwanted tops and leaves left in fields are the main winter food source) and milder weather and more food in Scotland.

A flock of Dark-bellied Brent Geese rise up from Burnham Overy marsh.

Apart from the Pinkfeet there are other species of wild geese that arrive each winter to seek food and sanctuary on the protected marshes of the north Norfolk coast, Holkham in particular. Probably most well-known to casual observers, second after the Pinkfeet would be the Brent Geese. Brents are smaller and darker and part of a different family of geese. Our geese come into two distinct groups; Anser or ‘grey geese’ like the Pinkfeet and common feral Greylags or Branta otherwise known as ‘black geese’ such as Canada, Barnacle and Brent Geese. Like many species of geese there are distinct sub geographical groups; different populations from distinct parts of the World. They might all nest in a certain area and then winter in another distinct area well away from others of their kind. Birds such as Barnacle Geese cover several widely separated areas of the Arctic in which they nest yet usually stay well apart in the winter but essentially they all look identical. The difference in the various Brent geese is that they have evolved so that they actually look different in different parts of their range. Here at Holkham we have been lucky as we have been able to see and compare these different forms. At the moment they are all deemed as identifiable sub-species yet with evolution still ongoing and the taxonomic scientists working overtime they might at some point all become species in their own right.

The common form of Brent Goose seen in Norfolk is the 'Dark-bellied'

The common form we see here in north Norfolk is the Dark-bellied Brent Goose. It arrives every September from breeding grounds on the tundra from northern and central Siberia and peaks at about 5000 feeding on short coastal grassland, cereal, saltmarshes and mudflats although numbers are far less than they were 20 years ago. Less common is the Pale-bellied Brent Goose. It nests in the Greenland, Canadian High Arctic, and Svalbard. Small numbers from the latter two populations appear in Norfolk amidst the Dark-bellied birds, with the Greenland birds most likely to be seen amongst the wintering Pinkfeet. A far rarer form, the Black Brant can be seen in even smaller numbers here in Norfolk, usually a couple per year. This form breeds from the central high Arctic Canada across to the Pacific coast of both North America and Asia. This is where things really start to become confusing (or interesting!) as where Dark-bellieds and Brants meet there is occasionally inter-breeding. 

The less numerous Pale-bellied Brent Goose

The striking looking black and white goose in the centre is the rare Black Brant

All geese traditionally remain a tight family unit during their first year, even during their migration south, it means when we see goose flocks here in the winter we can see both parentage and the amount of youngsters in each family. This year has seen an almost complete failing of the breeding Brent Geese, hardly any young in evidence and a phenomenon that frequently occurs. The success and failings of Arctic breeding Brent Geese is linked to the availability and abundance of rodents for predators such as Arctic Foxes. No Lemmings means baby geese are sought after as prey. What we have seen here at Holkham currently amidst the flocks of Brent Geese are all the different forms together in the same flock including some of those hybrids. Such identification conundrums have stirred up much interest from visiting birdwatchers at Lady Anne’s Drive, where the flock habitually frequents.

The birdwatcher's conundrum - one of our regularly occurring hybrid birds

Even more unusual for us this year is a potential English first – a Grey-bellied Brant. This fourth form in the Brent goose group of sub species has only recently been truly recognised (although some scientists are still arguing this!). It breeds in a relatively small area of western High Arctic Canada and winters solely in Puget Sound, western USA. In looks it appears intermediate between Black Brant and Pale-bellied and some observers initially thought they were hybrids although ongoing work has suggested that is not the case. The odd bird has turned up in Ireland but never in England so when a bird turned up amongst the Pinkfeet this October at Wells and then at Burnham Overy in November it proved a very exciting find for avid local goose-watchers. With scientific work continuing and evolution obviously very much ongoing it could be we have to wait quite some time before the mysteries of the whole Brent Goose group truly unravels. In the meantime have a look and you will see that everything is not quite just black and white!

This year's Grey-bellied Brant - a potential English first ?

Andy Bloomfield

Warden

The elusive cherry cracker

With its subtle mix of colours and enormous bill, the Hawfinch is unmistakable

Despite being a cold and unsettled period of the year with shorter daytime hours the winter can provide the avid naturalist with much to enthuse. Ordinarily, vast flocks of geese and wildfowl provide an over awing spectacle on the grazing marshes of the reserve yet at present our numbers seem well down on past years, a reflection of the mild autumn and early winter. There is however plenty of other sights to keep the enthusiasm levels up. One very elusive species in particular, the Hawfinch, is worthy of note at Holkham and I have been lucky enough to encounter it whilst doing routine work out and about on the reserve.

The Hawfinch is the UK’s largest finch and it is instantly recognisable due to its large conical beak. This is an amazing adaption that allows it to crush the seeds of beech, hornbeam, yew and even cherry stones. Special muscles surround its skull that enables it to use extreme pressure when crushing these very hard seeds. It has been estimated that it is capable of exerting the equivalent of 68 kg of pressure per square inch with its bill! Even its scientific name Coccothraustes coccothraustes, means ‘one who can break open kernels’. Not only is it a front heavy looking bird but it is a subtle yet pleasing mixture of orange (on its head), varying browns and greys and very odd looking shaped wing feathers. Small iridescent blue/black triangles form on the feather tips which are splayed out during the male’s intricate display ‘dance’. All in all it is a subtle yet quite exotic looking bird. What makes the Hawfinch even more special is that is usually incredibly elusive. Despite its size and looks it feeds unobtrusively either in the canopy of trees or on the ground. It always remains ever alert and fit to disappear at the slightest disturbance. Such behaviour makes any sighting all the more fortunate.

The Hawfinch is unique amongst British birds for having strange shaped primary wing feathers

Holkham has quite a long history with Hawfinches. When I was growing up on the Estate in the late 1970s and early 1980s the trees just inside the main gates were the best place in Norfolk for seeing them. Here they fed in the winter on fallen hornbeam seeds before moving around the Park in the spring ready to nest. Open parkland or large country gardens with a mix of deciduous trees (including plenty of beech and cherry) make the ideal habitat and in the past the grounds of both the Hall itself and the Walled Garden were nesting sites. Like so many of our song birds, a decline has been noted all across the UK and it is now a very scarce bird. Up to 75% of the breeding population has gone within a 40 year period. Declines have been blamed in part to dropping insect numbers (caterpillars are the main food of the young) and also the vulnerability of their frail open nest sites to predators such as Grey Squirrels and bird such as Jays and Magpies.

A freshly fledged juvenile; not a sight often seen.

At Holkham my past is littered with great Hawfinch moments. My old departed Uncle who was gardener at Quarles Farm after the Second World War told me with great sadness how he had found a freshly dead one on the lawn close to the vegetable patch. He suspected it had been after his prize peas (another known food source from when they were more numerous) and been attacked by a Sparrowhawk as it was departing. I was once very fortunate in witnessing a male display to a female prior to copulation. This involved a spectacular courtship ritual/dance with head held skywards, wings stretched out as he wandered around dipping and bowing in front of his mate. It was one of those once in a life time moments that I had read about in a book, yet never expected to see. I suppose however the ultimate find was discovering a nest, complete with two fledglings in the cleft of a Holm Oak tree close to the Walled Garden. The next day they had fledged and were sitting on a branch awaiting their parents with food. Sadly since the new millennium Hawfinches have all but disappeared from Holkham Park until recent times.

Juveniles have a more yellow look to their faces

This autumn we were working in the Dell within Wells Pinewoods, raking up grass we had cut when a familiar explosive almost metallic ticking call cut through the air. It was a Hawfinch and it flew right over our heads, its white wing bars illuminating its striking bounding flight. A moment to cherish but one that was not in isolation as this autumn saw a tremendous influx into England of migrant Hawfinches from the Continent. Flocks and odd ones and twos were reported far and wide as a result some have said of poor food availability in Eastern Europe and storms over Europe that pushed the wandering finches our way. It is hoped that such an invasion will allow our native breeding population to re-establish itself and perhaps we might even see this elusive bird start to nest again within the grounds of the Estate. We certainly have currently got a regular pair back in their old haunts just inside the main gates, feeding under the same hornbeams and in the same yew tree that I saw my first ever ones in over 35 years ago.

Andy Bloomfield

Warden

Thanks to Roger Tidman for his spectacular images.

Glimpses of 'Golden' Mice

One of our traditional tasks at this time of year is the management of several of our grassland areas. This involves cutting, either with strimmers or in some of the larger areas with tractor and then raking up all cut material by hand. Cutting prevents areas turning to scrub and by removing the cuttings it prevents unwanted nutrients building up and enriching the soil. The resulting shorter swards of grass are then good for an assortment of wild flowers which otherwise would find it impossible to compete or survive within too much shade or with other more vigorously growing species.

The prehensile tail of the Harvest Mouse acts like a fifth limb

By working in such environments by hand it gives an opportunity to see close up some of the inhabitants that are normally hidden away from view. Admittedly in the autumn when we are doing such work there is less to be seen as most invertebrates are coming to the end of their short lives and most plants have long since finished flowering but there are always plenty of clues as to what has been and what is to come! One such example of a species we seldom see is the Harvest Mouse. Whilst these rather cute tiny golden orange rodents with their long prehensile tails are still reasonably common in the UK south of Yorkshire and east of Wales, they can be difficult to find, let alone observe. Declines have been suggested due to intensive mechanised arable farming yet the true population size is really unknown. Harvest Mice prefer rank grassland and here on the coast, dry reedbeds. They can also be found along old hedgerows, in fallow fields and less intensively managed farmland. 

Weighing as little as four grams, the Harvest Mouse is Europe's smallest rodent

As they are Europe’s smallest rodent they can be virtually impossible to find. Often the only clue as to their whereabouts is the sight of a distinctive nest. This is a golf ball sized bundle of tightly woven grass and every time we work in such places we always find one or two Harvest Mice nests, suggesting they are actually quite widespread across the reserve. One constant surprise is that every time we have a tidal surge we find dead Harvest Mice. This really does suggest that there is a far larger population out in the rank saltmarsh grasses than is generally recognised and that they can adapt and live in conditions out of their more normal accepted habitat.

Harvest Mice nests have a dual purpose. Summer maternal nests are said to be solely for that reason; producing offspring and are then abandoned. Winter roosts are said to be in different purpose made nests, with the remnants of food, such as discarded seed husks being a sign of recent occupancy. So to see an actual Harvest Mouse requires an awful amount of luck. Some people live a life time and never get a glimpse of a wild, live one. Everyone recognises one from a book as they are so distinctive and being so brightly coloured surely they should be easy to see? No, not the case as they live close to the ground keeping well out of the way of all manner of predators. They do venture up reeds and grass stems quite freely due to their long hairless and prehensile tail. It really does act like a fifth limb. 

A sight that very few people have seen in the wild; a nest of young Harvest Mice

My own sightings seemed a long time coming but in recent years working on the reserve I have been fortunate in seeing them from time to time. Even then to see a wild one cling onto a grass stem is an incredibly lucky experience. I have seen it only once and that came as a matter of sheer good luck. I was walking through the dunes close to the foreshore and heard a series of short rasping squeaks. I always try and check out such noises as you can never be sure what you will see and on this occasion I hit gold. Literally! Three dark golden mice scattered on the marram tops in front of me. They were youngsters, probably only just weaned from their nest, their skinny tails enabling them to cling precariously to the grass stems. I never saw the adults, they were probably well hidden, but these fearless youngsters gave me my first and only real close up experience of wild Harvest Mice doing what everyone wants to see a Harvest Mouse do. Other than that my only other glimpses have been whilst working. Occasionally I have flushed a golden shape as it scampers out from some reed litter whilst reed cutting never to be seen again. More regular observations have come when topping the marshes by tractor. Kestrels are never far from the scene and sometimes amidst the more typical Field Vole prey items they dive down and snatch up the odd Harvest Mouse too. Sightings such as this combined with nests we find are certainly enough for us to know we have a widespread population on the reserve although at what sort of densities we do not.

Andy Bloomfield

Warden

Many thanks to Roger Tidman for the pictures of the Harvest Mice

Autumnal Dragons and chequered Walls

As October turned to November this year all thoughts should really have been aimed at the dawn of winter. With the temperatures continuing to be mild (only one frost logged by mid-November) and little rainfall it really did seem like the autumn was carrying on with no end in sight. I’m sure that won’t be the case for much longer, but in the meantime we can reflect on some of the rather more unseasonal sights that have continued to be seen on the reserve. As I write this (on November 29th) there is quite miraculously still a Swallow hawking for the last remaining insects around the beach car park at Wells.

A male Common Darter soaking up some late autumn sunshine

First and foremost of unseasonal sights has been the continual appearance of Common Darter dragonflies (at least up until mid-month). On sunny calm days it has not been unusual to see the distinctive elongated shape of these winged insects flying back and forth over sheltered spots within the more open southern edge of the pinewoods. Their movements can be erratic, fast and dashing one moment, slow and hovering the next before pausing to alight on exposed logs or branches that are facing into the full sun. Little wonder they are known as darters. They are certainly always darting from place to place constantly looking for a spot to bask in as if soaking up every bit of the late autumn sunshine. One last sun bathing session before their ultimate demise! Whilst not sitting in the sun they are always busy looking for smaller insects to feed upon. This is why most insects are no longer on view in the winter, too cold and little in the way of food. Dragonflies of course live a longer life as an aquatic ‘nymph’. Eggs are laid by the adults either on waterside vegetation or in the water from which the larvae (the nymph) emerges and after roughly a year, for the Common Darter,  it will metamorphasize into the adult dragonfly we have still been seeing of late. 

Any flat surfaces such as the bark of tree trunks or logs that are exposed to the Sun make perfect basking spots for Common Darters

I always think Common Darters blend in quite nicely to the autumn scene, the vivid orangey red of the males being a similar tone to the hips and haws that they frequently perch beside, whilst the drabber females harmonise perfectly into the background of leafless bark and trunks. This is in contrast to when they first emerge in August, then they are more of a dull yellow. One of my nicest memories of this autumn was whilst strimming the glades alongside the track near Meales House and counting 13 Common Darters all lined up together on a single log and all facing in the same direction. It really looked like they had been stuck there, until a marauding wasp came flying along. It purposefully homed in on a single darter, trying desperately to grab it on the back of the head. Several attempts were made, yet each time the lightning fast reactions of the darter allowed it to escape.

Five of an eventual total of 13

This female was photographed in August, its yellow colouration fresh and pristine

At the end of October we also enjoyed seeing a selection of late butterflies. Some species will have third broods of adults if nice weather prevails into the autumn and that is exactly what happened this year. Wall Browns, Brown Argus, Common Blues and Small Coppers were all seen at the month’s end on the dunes in very fresh condition, a sure sign that they had not long emerged. For the Wall Brown this was most encouraging as it is a fast declining species in much of its UK range. It prefers short cropped grass in places such as cliffs and sand dunes where it lays its eggs on grasses. Here at Holkham it has always been a regular sight, yet numbers did start to drop about ten years ago. We still see enough to know that it is holding its own, yet numbers are never as great as they once were. Most sightings come in late April/May and again in August but late October records are every few and far between. Being a chequered orange and black it is quite an easy species to see, particularly when it basks in the sun on stony outcrops or walls, which is where it got its name from !

A freshly emerged Wall Brown

Andy Bloomfield

Warden

Flight of the Fish Hawk

The Osprey, one of the UK's most spectacular birds

Without a doubt one of the most spectacular sights of nature within the British Isles is that of an Osprey plunging down into a lake to catch a fish. With a wingspan close on five and a half feet the bird is an impressive enough sight alone, yet when it splashes into the water head and feet first after a spiralling plummet from great height, the spray of water and audible crash leaves a lasting over-awing impression of natural power and precision diving. Within the regularly seen range of British birds of prey the Osprey is one of the biggest with only the eagles larger and it has evolved with unique adaptions for its fish catching habits. It has incredibly long curved talons of which the outer ones are reversible, it has backwards facing scales on its feet that act like barbs when clinging onto a fish while it nostrils are able to close when it dives underwater.

The recent Osprey at Holkham Lake in the process of devouring a fish

Not only is the Osprey a spectacular looking bird but it is also quite a rarity. Once widespread over much of Britain it was persecuted to such an extent in Victorian times that it was feared to be nationally extinct by 1916. A slow process of re-colonization begun in the 1950s in Scotland and thanks to greater protection initiatives the species had increased to close on 300 pairs by 2011. Re-introduction in the Midlands around Rutland Water has also helped the species move south into suitable habitat away from the lochs and rivers of Scotland, its traditional homeland. Our UK Ospreys are migrant birds, heading south into Africa to spend the winter after a breeding season in the north. And this is where Norfolk and Holkham come into the story. Despite still being a rare sight within Norfolk they are still regular enough to be recognised as a passing migrant both in Spring and Autumn. Occasionally birds might make longer stays at places such as the Norfolk Broads, the West Norfolk fishing lakes and even Holkham Lake.

Holkham Lake occasionally attracts passing migrant Ospreys

At Holkham we eagerly anticipate the appearance of one or two each year but usually they are just passing through. Blink and you miss them! You always know when an Osprey is about due to the sense of sheer panic shown by other birds on the ground. Here on the coast flocks of gulls and ducks along the marshes erupt en masse when the long winged shape of an Osprey drifts overhead. Migrating Ospreys actually look a bit like large gulls, due to their white underparts and lazy bowed winged profile even though they can sometimes pass at great height. Holkham’s marshes and lake has however through the years managed to attract a few lingering birds all that have left a lasting impression with those lucky enough to have seen them.

My first view of this year's Osprey, overhead from the tractor window!

One such bird arrived this September. I had heard several reports of one flying over the marsh causing its usual sense of panic but always managed to be in the wrong place to see it, yet that soon came to end one day when I was out topping in the tractor. Geese, gulls and ducks flying in every direction, the local Marsh Harriers and kites all flying up to investigate and there amongst this melee of wings was an Osprey! It circled the marsh even dropping low over where I was working before heading off towards Holkham Park and the lake. We later heard from one of the keepers that it had been visiting periodically, fish the undoubted attraction. As the weeks progressed so it turned out that the bird settled down into a little routine – flight out and around the nature reserve before returning to fish on the lake. Here it would sit up on the tallest trees seemingly admiring its surrounding before periodically sailing around the length of the lake, hovering with great ponderous wing beats and crashing into the water. This particular bird was a juvenile perhaps from a Scottish or even Scandinavian nest pausing on its southbound migration, its immaturity perhaps explaining why its fishing forays were not always successful. About one in four attempts usually resulted in a catch. 

Claws outstretched, head tucked in line with talons, wings swept back, impact imminent!

Splashdown! Only the bird's wings tips can be seen amidst the spray of crashing water

Like many other keen naturalists I spent my time off encamped along the lake’s shore waiting for that magical moment when amidst a crescendo of wings and water I hoped to see the Osprey emerge with a fish. Holkham Lake’s association with Ospreys goes back further than this year’s social media celebrity. One of my own most cherished sightings is of a similar young autumn visiting Osprey in the 1990s. It caught a fish so large on the west shore that it had to swim/clamour its way through the shallows. I was hidden behind a tree about ten feet away. I could see the glint in its eye and the wind take away the fish scales as it was ripping apart its prey. Even further back in time was the pair of Ospreys that made the lake their home in May 1970. Sticks were being carried and a likely nesting attempt seemed more than a fanciful thought. Yet their efforts were perhaps merely a practise for a more concerted attempt further north as they departed never to be seen again.

Osprey and Great Crested Grebe;two Holkham Lake fishermen, one successful as the other looks on!

Andy Bloomfield

Warden

Digging up emeralds

Ditching work at Holkham's marshes

Anyone glancing over the marshes at Holkham in September and October is bound to have seen a large yellow tracked digger. Many people stop and ask what sort of work is it doing? The simple answer is that it is dredging the ditch systems, yet really the answer is a lot more involved than just simply doing a bit of dredging work.  Together with a series of sluices the ditches help us manage the water levels. For the ditches to do their job a certain amount of maintenance has to be done regularly and this means dredging out silty mud that accumulates and impedes the water flow.  As you can imagine the wildlife of the dykes is varied and often prolific. For that reason we try to work on a seven year rotation so that there is plenty of time for the flora and fauna to re-establish.

The Grey Herons of the marsh become most confiding during ditching work ever on the lookout for fish and eels.

Whilst we do not actually drive the machines ourselves we are often at hand assisting the driver in clearing up rubbish that has been ‘slubbed’ out or helping replace culverts and gateways.  It can be messy work but the amount of wildlife seen can be quite astounding. The dykes of Holkham are an incredibly important part of our ecosystem and a great indicator of their health is the presence of Eels. They are always encouraging to see and form an essential part of the menu of birds such as Bitterns and Grey Herons. It is quite normal to see two or three Grey Herons or even the odd Little Egret wandering about on the ‘slubbings’ metres  away from the digger looking for rich pickings. A good number of fish are also present, Roach in particular. We are quite unaware at just how many we have, but suffice to say there must be plenty judging from the concentrations we occasionally see and the constant fishing activities witnessed by our newest residents, the Great White Egrets. They are constantly pacing back and forth through the shallows of the dykes these days in search of fish to eat.

The Willow Emerald Damselfly, a new species for the reserve

As I was helping out one day this year a flash of green caught my eye on some waterside reed. It was a small elongated yet dainty damselfly. A closer inspection revealed it to be a Willow Emerald and a new species for the reserve. This southern European species first colonised the Suffolk coast in 2009 and has been slowly pushing north ever since. This year has seen more than normal numbers appear along the coast of north Norfolk and it had been a species we were expecting to find at some stage. It prefers dykes that have overhanging willows where it lays its eggs under the bark. With some of our dykes having willows in sunny situations it really does look like we perhaps have the perfect habitat for a future flourishing population.

A fearsome looking Water Scorpion

Another interesting insect seen was a Water Scorpion. This rather fierce looking insect (unrelated to a true scorpion) has a long ‘sting’ like protuberance at its rear end yet this is actually a respiratory tube that it holds above the water thus allowing it to breath underwater. Instead of having claws on its front legs like a Scorpion it actually has scythe-like front legs that are still used in a similar fashion to catch its prey.

Water Shrew, a rarely seen inhabitant of the reserve's dykes

For me however the most exciting find of the year was a Water Shrew. Having been a keen naturalist for 36 years it was a species that I should have seen before but it had always eluded me. It is also said to be a relatively common well distributed species across the British Isles yet one that is pretty much solely aquatic and that was my excuse for not having seen one. There have been one or two sightings through the years on the reserve, yet never by me so when I saw a very dark almost black shrew, I knew my luck was about to change. It proved to be a very worthwhile learning experience. Water Shrews have Mole-like black fur above and most have contrasting white underparts; this one however was more dusky coloured below making it not so easy to identify. Certain features could be seen that eliminated the more widespread Common Shrew such as its larger size, its pale tipped ears and its hairy feet, toes and tail which have evolved to enable it to swim through the water with ease. It could well be a common species on the reserve or it could be a rarity, something we currently cannot answer.

The fresh foot prints of an Otter

Another mammal that continues to elude me on the reserve is the Otter. A regular recently told me when he was young in the early 1950s he used to ‘bunk off’ school especially to watch a family of Otters sliding into one of the ditches on the marsh. Following the species nationwide demise due to the use of organo-chloride pesticides running off into river systems it took until after the new millennium for Otters to return to Holkham. Since 2012 we know through finding foot prints that the species is now present again, but being mostly nocturnal it remains very difficult to see. I think I must now be the only member of staff who works on the reserve who has yet to see an Otter here, but I’m sure that time will come soon. Another reason they are so difficult to see is the sheer distance they travel. Between Wells and Burnham Norton the reserve’s three main areas of grazing marshes are an intricate wetland of cattle grazed fields that are all bordered and inter connected by a series of fresh water dykes and ‘drains’. This again brings us back to the management of the reserve and the reasons for dyke dredging. The basic system works like this; water accumulates, be it rain water or from in-field springs and drains into the dykes which then ultimately flow out through the fields to the sea. Some are old ‘foot’ drains used from the 1700s onwards when the fields (formerly brackish and salt marshes) were drained so that the arable crops could be grown. We are able to control this flow due to a series of dams and sluices that allows us to either hold back and retain water (giving us wetter fields) or release it (thus drying areas out).

Andy Bloomfield

Warden