Monday, 31 August 2015

Recent Sightings - August

August seems to have been the month of change, and I don’t just mean the weather. Change is definitely in the air as small flocks of birds begin to migrate.

Autumn’s passage waders are a little stop start at the moment with 100+ Curlew, 5 Greenshank, 6 Green Sandpipers, 1 Common Sandpiper, and 7 Wood Sandpipers gathering on the pools at Holkham. Yesterday there were signs of Spotted Redshank with their silvery grey and white winter plumage, Ruff and a Jack Snipe near Washington Hide.

Can you spot these camouflaged 
Snipe at Washington Hide? 

 It’s also been a good time for passage migrants. These birds pass through the British Isles in autumn on their way south to Africa having spent the summer in northern Europe. There have been several sightings of warblers including a good showing of an Icterine Warbler. Many people had excellent views of this traditionally shy bird however, that cannot be said of a young Barred Warbler, which stayed well hidden in the dunes. The numbers of other warblers arriving are also slowly increasing such as Blackcap, and Whitethroats. Common migrants have also been arriving in good number. Wheatears and Redstarts have joined the growing number of Whinchats. Even a Red-backed Shrike was seen dropping into the sloe bushes on the Holkham-to-Wells Backtrack.

Look out for migratory tit folks as they may
 shelter rare birds including Yellow Browed Warbler.

A Great White Egret is well into its 2nd week on the reserve and has settled on the scrape nearest Decoy Wood. Although it is only appearing now and then, with a lot of patience and a bit of luck you can get a good view as it stalks the shallow waters of the dykes along the grazing marsh.

A rather raggedy Great White Egret.

Despite the recent rain, birds of prey have been showing regularly including Marsh Harriers, Kestrels, Sparrow Hawks and Common Buzzards (2 in stunning pale plumage) and an often-seen Peregrine Falcon (outside Jordan Hide). In the last few days a Short Eared Owl has also been sighted dropping into the dunes at Burnham Overy.

In contrast, sea-bird sightings on the reserve have been very poor with only a small group of Gannets seen passing far out to sea. However, the bad weather did sweep in an unlikely Little Gull into the Overy dunes/Gun Hill area of the reserve.

Keep an eye out for late butterfly's and their chrysalis 
like this beautiful gold Small Tortoiseshell chrysalis.

The rain flatted much of the tall grass, and as a result conditions were great for mammal watching. Common and Short-tailed Shrews could be seen moving thorough the grassy verges  (and often being eaten by Herons!)

With the start of September we can look forward to many more migrants arriving and passing through Holkham NNR. With north winds we should see the arrival of the first flocks of Fieldfares and Pink-footed Geese!

Monday, 24 August 2015

The Dunes of Holkham

 When most visitors think of Holkham they think of its unspoilt beach and stunning sand dunes. The sand dunes are a key feature of the area and this has led to many people asking me, how they were formed.

There are approximately 11,897 ha of sand dunes in England with 1,200 ha here in Norfolk.
Dune grassland and dune slacks support a wide variety of plants and are rich in invertebrates. The dune system at Holkham is protected by a number of conservation designations, such as SSSI and SAC. This is the reason why horses and bikes are not allowed access through the dunes.

Along with the beach, the dunes are one of Holkham's 
most famous features.

The sand dunes at Holkham were formed because there is a large beach plain, so plenty of sand. The surface dries out between high tides, and then dry sand is blown landwards by strong onshore winds and deposited along a shingle ridge above the high water mark. At Holkham the dunes are unusual as they are rather alkaline due to the amount of shells in the area.

Embryo Dunes are the first stage. There is very little vegetation and sand is only just starting to accumulate.

Lots of bare sand and
 little vegetation.

Foredunes are part of the sand dune system on the side nearest to the sea. They are comprised of wind blown sand and scattered plants, such as sand couch-grass and sea rocket. As embryo dunes build up, the surface is raised so as to be out of reach of all but the highest tides.

Large hillocks of Marram grass.

Yellow dunes are yellow in colour because of a lack of soil. They are dominated by marram grass. Marram grass is tall, robust, flexible in the wind and very effective at trapping sand. Their binding rhizomes help stabilise the sand dunes and enable other species to grow, such as sea sandwort. The dunes grow to around 5m.

Vegetation has become varied and dense.

Grey dunes are grey in colour because of the presence of soil. As dead leaves from the marram grass breaks down so plant nutrients are released into the soil improving the conditions for plant growth. Due to an increasing distance from the sea vegetation diversity increases, though the plants are still highly specialised. Marram grass is still abundant but other species are able to colonise the area, such as red fescue and bird’s foot trefoil. Grey dunes grow to between 8 – 10 m high.

Core samples have shown that the Holkham dunes are 
200 years old!

Dune Slacks occur when the surface of the sand dune is eroded down to the water table and wet sand is exposed. A secondary dune slack can have the appearance of a bomb crater! Dune slacks can be extremely species rich. As well as rare orchid species there are a number of uncommon species of butterfly, dragonfly and the very rare vulnerable natterjack toad.

Dunes slacks are rare and unique habitats.

Through careful sympathetic management the warden team aim to ensure that there is a succession of dune slacks at different stages of re-colonisation, thereby providing a habitat for rare flora and fauna, to control the invasion of non-native species and to protect the sand dunes from erosion by recreational use.

When you next walk along the dunes at Holkham National Nature Reserve why not try and identify these stages. The coast is always changing so there is always something to see!

Happy Hunting
Jonathan Holt

Monday, 10 August 2015

A Life on Ragwort

Common Ragwort (also known as Stinking Willie) is a native biennial plant which often grows naturally on uncultivated land. The problem with Common Ragwort is, it is toxic  and if left unchecked can seed through large areas. Ragwort is poisonous to livestock especially horses but fortunately most mammals are aware of its toxicity and avoid eating the plant. Ragwort is very distinctive with finely divided deep cut toothed leaves and large flat-topped clusters of yellow daisy-like flowers. It flowers from July to October and is a good late nectar source for hungry insects.

Despite its hazards many species depend on Ragwort and live their entire life cycle on the plant. Therefore, Holkham National Nature Reserve takes a balanced approach. Ragwort does need controlling but not eradicating and we take all reasonable action to do this on the nature reserve. We manage the spread of Ragwort on the grazing marsh by grazing cattle but as a natural dune flora Ragwort is left unmanaged on the dune system.

Ragwort will quickly take over a field if it isn't controlled.


Cinnabar Moth Caterpillar
Ragwort (mainly common ragwort) is the sole food plant for the golden and black banded caterpillar of the Cinnabar moth. The caterpillars feed from July to September and act as a biological control by eating the whole plant. The poison from the ragwort leaves is stored in the caterpillar's body. The bold colours and patterns are a warning to birds and other predators that they are extremely unpleasant to eat.   

These caterpillars are both eye 
catching and alarming at the 
same time!

Bumblebees are a familiar sight during hot summer days with their characteristic behaviour and distinctive buzzing sound. Sadly, bumblebees are in massive decline due to the reduction and removal of hay meadows and hedgerows from the British landscape. Ragwort flowers are an important source of food for many bees. These include the obvious Red-tail Bumblebee, the bird box dwelling Tree Bumblebees and the distinctively ginger Common Carder Bee.

A Common Carder Bumblebee 
(unfortunately not on a Ragwort flower!).

Forester Moth
This exquisitely coloured metallic-green and remarkably well camouflaged moth is a UKBAP species. It is thought to of been named after the "Lincoln Green" worn by the foresters in Sherwood Forest. The species is in decline but can be found locally in the coastal marshes and around damp meadows. We found this fellow while ragwort pulling on the Fort. It just goes to show the diversity of species that can be found on ragwort.

A lucky find!

Cockchafer Grub

Possibly the most unluckily named insect out there, it is also known as the Maybug though it's not a bug, these large beetles actually belong to the scarab family. The harmless beetle is a distinctive brown colour with characteristic fan like antennae. Cockchafers spend most of their lives (three to four years) underground as larvae. The larvae (which are called Rook Worms) are fat, creamy-white grubs with brown heads that feed on the root systems of ragwort. In turn these grubs are fed upon by badgers, owls and bats!

Both adults and grubs are considered 
delicacy and are still eaten in some 

Jonathan Holt

Monday, 3 August 2015

Recent Sightings - July

Firstly, I must apologise for no updates recently. We have been unbelievably busy on the reserve and I must admit to a few days holiday.

The month started warm and sunny with lots of bird and invertebrate activity but it's ended cool, wet and very windy, causing bird and invertebrate activity to become subdued.

On site there has been a good selection of waders spread right across the marshes with up to 100 Black Tailed Godwit, 24 Avocet, 4 Spotted Redshank, 5 Greenshank, 17 Redshank as well as Curlew, Oystercatchers and a good number of Ruff. The males are looking rather attractive with their wide variety of different plumage due to their various stages of moult. In the evenings it is always worth looking upwards particularly at high tide as we have had almost 100 Common Scoters fly past!  And, the odd Whimbrel has been seen passing over the reserve flying west.

A lonely Curlew surveys its watery
 territory during high tide at Norton.

Other notable birds include plenty of Little Egrets that can still be seen hunting in the shallow dykes. A Green Woodpecker family has been very noisy in the pine woods at Holkham NNR and a lucky Quail that survived the guns of Malta was heard (but not seen) by myself and others at Whincover.

There have been excellent sightings of Marsh Harriers from both hides. As you approach the reserve you can get some stunning views of the harriers with newly independent youngsters hunting in the fields near the coast road giving some good photo opportunities. There has been plenty of Red Kite activity and the odd Buzzard too but no more sightings of the Short eared or Little owlBarn Owls have been showing very well especially near Washington Hide. Early evening is the best time to see them but remember the reserve gates are being locked at 9:00pm very evening until October.

Unlike their Hen Harrier cousins the Marsh
Harrier is slowly recovering from near 
extinction in Britain but they remain rarer 
than Golden Eagle.

I enjoyed a very interesting evening while walking through the reserve last week. I saw 16 Brown Hares grazing and chasing each other in the fields (they have a long extended breeding season, so are still quite frisky) then, some lovely Roe Deer on the old railway line but the evening was to get even better when, walking through the Natterjack ponds I noticed a young Hedgehog sat right in front of me. It decided it was quite comfy where it was and sat there until I had to go home.

Due to the mostly nocturnal nature of Hedgehogs it is 
difficult to assess their numbers on the reserve.

There were a lot more butterflies at the start of the month when the weather was warm and sunny such as Grayling, Essex Skipper and  White Admiral, dragonflies included Emperor and Southern Hawker as well one of my personal favourites, the Hummingbird Hawk Moth. However, despite the recent cool wet weather there are still several species still active, such as Forester Moth, Gate Keepers Butterfly and Ruddy Darters.

The Emperor is one of the UKs largest 
Dragonfly's it is brightly coloured and 
rarely lands even eating its prey on the wing.

I’m still pretty disappointed that the Minsmere Albatross didn’t pay Holkham a visit but maybe next time.

Jonathan Holt