Tuesday, 27 February 2018

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


Wednesday, 31 January 2018

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


Friday, 12 January 2018

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


Thanks to Roger Tidman for his spectacular images.