Pentewan Valley and Black Head circular walk
  1. Turn right out of the car park and follow the road along the wall and past the Ship Inn to the village square.

    Pentewan dates back to mediaeval times when it was mainly a fishing village with a harbour. The harbour was rebuilt in the 1820s both for the pilchard fishery and to create a china clay port. At its peak, a third of Cornwall's china clay was shipped from Pentewan. However the harbour had continual silting problems which meant that it was eventually overtaken by Charlestown and Par. As well as longshore drift carrying sand east across Mevagissey Bay, there was also silt being washed down the river from china clay works and tin streaming. Consequently, the harbour gradually silted up with the last trading ship leaving in 1940 and World War II literally sealing its fate. By the 1960s, the harbour was only accessible to small boats and today the harbour basin is entirely cut off from the sea.

  2. Walk through the square and follow the lane ahead up Pentewan Hill until you reach a track on the right with a "The Terrace" sign.

    Pentewan is famous for its stone which is a type of elvan.

    Elvan is very hard volcanic rock formed where magma intruded into other rocks to form a (vertical) dyke or (horizontal) sill that cooled fairly quickly, resulting in fairly small crystals. Elvan can be seen in many of the churches across Cornwall where it is often used for intricate parts of buildings, such as doorways, so they can be finely carved.

    The term "white elvan" is sometimes used for those which are chemically very similar to granite (but in the case of granite, slower cooling resulted in large crystals) i.e. formed of mildly acidic compounds.

    The term "greenstone" is used by quarrymen to describe igneous rocks that, unlike granite, are rich in (basic) iron and magnesium compounds and these often give it a blue-green colour. When greenstone is formed as a sill or dyke it is sometimes called "blue elvan". This is also fairly common in Cornwall and has been quarried for a long time: in the Neolithic period, stone axes made from blue elvan were exported from Cornwall to various parts of Britain.

  3. Turn right onto the track and follow it past the church to where the gravel ends and tarmac begins. Continue a few paces further to the entrance to no. 11 with a signposted footpath to the left of this.

    All Saints Church was completed in 1821 as part of a plan for a terrace in which it was envisaged as the centrepiece, but only the northern half was ever built. It is built from the famous Pentewan Stone and the terrace incorporates tracery from the Elizabethan Polrudden House which was destroyed by French pirates. The church fell into disuse within a few decades and was used as a carpenters shop until it was restored and reinstated as a church in 1878. There was also a Methodist church in the village but this was destroyed when Pentewan was bombed during the Second World War.

  4. Keep left to join the footpath and walk a few paces to reach a waymarked path departing to the left up a couple of steps. Turn left up the steps and follow the coast path until you eventually reach a wooden stile.

    As you climb up the steps towards the stile, the rocky cove on your right is known as Polrudden, which means "Red Cove" in Cornish. There is a sandy beach at low tide where ships used to land to collect stone from the Pentewan quarries.

    The golden yellow elvan known as Pentewan Stone was used in many mediaeval churches as its fine grain allowed stone masons to carve it into intricate shapes without it crumbling. The earliest use found is an inscribed stone at St Cuby, Tregony which dates from the Dark Ages. In mediaeval times, the stone was obtained from where the volcanic dyke met the cliffs of Polrudden Cove. Later, quarries were opened up inland along the course of the dyke and these can be traced for nearly a kilometre to a large overgrown quarry behind the village. In 1985, when the church at St Austell was restored, blocks of Pentewan Stone were recovered from Polrudden beach for the work.

  5. Cross the stile and follow the footpath around the headland, down the valley and up the other side, and around the next headland to reach a footbridge.

    Just before you reach the footbridge, the sand/shingle beach at the bottom of the cliff is known as Polgwyn. This means "White Cove" in Cornish and is probably a reference to the white shingle beach.

  6. Cross the footbridge and follow the path along the coast and eventually down some steps into a wooded valley to reach a footbridge at the bottom.

    Although primroses flower most intensely in March and April, some primroses can begin flowering in late December. The name "primrose" from the Latin for "first" (as in "primary"), alluding to their early flowering.

    Oystercatchers are recognisable by their black-and-white bodies, their long, straight red beaks and loud, piercing call. In flight, the white markings form an image of a white bird towards the back of their otherwise black backs which may have evolved to confuse predators.

    The long beaks are adapted to open shellfish - mainly cockles and mussels - "cocklecatchers" would be a more accurate name. They can also use their bill to probe for worms.

  7. Cross the footbridge and turn right. Follow the path towards the coast until you cross over the driveway to a cottage and reach a waymark at a junction of paths.

    In Elizabethan times, starch made from the bulbs was used to stiffen collars and cuffs in clothing. The ruffs that were highly fashionable at the time would have needed a lot of starch to prevent them flopping. The toxins in bluebell sap might also have had the desirable property of preventing the starch encouraging the formation of mould.

    The Latin name for the hemlock's genus (Conium) comes from the Ancient Greek word for hemlock. This word itself may be related to the Greek word for "whirl" as vertigo is one of the symptoms of ingesting the plant. The name hemlock is from the Old English word for the plant (hymlic which meant "hop-like", based on a vague resemblance to the vine on which hops grow). Other common names include "poison parsley" and "devil's porridge".

  8. Bear left at the waymark and follow the path uphill a short distance to reach another waymark with a small path leading uphill to the right.

    At the cottage, the path to the right leads to Hallane Beach.

    Hallane is a south-facing shingle beach with submerged rocks a short way offshore which surface as the tide goes out, and at low tide, a rocky platform is exposed along the shoreline. It is very sheltered which makes it suitable for swimming, and the offshore rocks provide a suitable spot for a rest and warm-up although care must be taken of the sharp barnacles. On the right-hand side of the beach, a waterfall cascades over a natural arch. At low tide, it is possible to walk around the arch to get behind the waterfall; slippery algae grows on the rocks beneath the waterfall so climbing through it is not recommended.

  9. Turn right at the (blue) waymark and follow the path to another (yellow) waymark in the field. Continue ahead along the fence and follow the coast path until you eventually reach a junction of paths beside a huge granite memorial.

    The plants along the coast path with yellow flower spikes are dark mullein.

    Mulleins are biennial plants of the Verbascum family with fuzzy leaves which produce a massive spike of yellow flowers in their second year. Two species are fairly common: common mullein can reach 6-8ft tall and has all-yellow flowers where as dark mullein is a bit smaller and the flowers have purple stamens.

    Common names include "Jacob's staff", "Jupiter's staff" and "Aaron's rod" which all reference the tall flower spike. The plant's soft, fuzzy leaves are featured in names such as "bunny's ears", "flannel leaf", and the delightful "cowboy toilet paper" from the USA.

    Other names include "Candlewick plant" which refers to the use of the dried down from the leaves to make wicks for lamps. The use of mullein for torches dates back at least to Roman times. The association of torches with witches also gave rise to another name for the plant: "hag taper".

    The granite memorial on Black Head, engraved with "This was the land of my content", was erected in the memory of Arthur Leslie Rowse, a Cornish writer and historian. Rowse was born in 1903, the son of an uneducated china clay worker, and was the first Cornishman to win a university scholarship, reading English at Christchurch College, Oxford.

  10. Turn left at the memorial and follow the path inland to reach a fork in the path with a flight of steps in the right-hand path and a "15/E" green marker on the tree above.

    At the memorial, the path to the left leads out onto the headland.

    The name "Black Head" dates back to at least Tudor times. A map from 1576 records it as The Blak heade poynt. From the North side there are views across St Austell Bay and to the South, across Mevagissey Bay to Chapel Point.

    Black Head was the site of an Iron Age fort which is thought to date from around the 3rd Century BC. Two large banks and ditches are clearly visible across the narrowest part of the headland. There were originally three ramparts but the outermost has almost vanished.

  11. Keep right at the fork and follow the path up the steps and along the coast to the Ropehaven Cliffs Nature Reserve sign and continue along the path to a junction with another path at the top of a flight of steps.

    The lines of buoys out from Ropehaven were England's first offshore mussel farms. A line runs between two weights on the bottom and this is lifted to a couple of metres below the surface by the floats. The mussels are grown on ropes suspended from this which don't touch the seabed, ensuring they don't pick up grit and as many barnacles. They are naturally-occurring blue mussels which at their planktonic stage look for any suitable attachment to grow on, and attach themselves to the ropes. The ropes are initially coiled to suspend them in the top couple of metres of water where the mussel plankton (known as "spat") are most prevalent. Once the mussels begin to grow, the ropes are uncoiled to give them more space and to protect them from seabirds and other surface predation. EU restrictions on importing shellfish have reduced the size of the viable market for mussels so there is a pilot project to try growing seaweed on some of the ropes instead.

  12. At the junction, bear right down the steps and follow the path until you reach a bench with a waymark opposite. Turn left in the direction waymarked and stay on the main path leading gradually uphill until it emerges onto a track.

    A 49 acre area of the cliffs above Ropehaven was purchased by the Cornwall Wildlife Trust in 1986 to create a nature reserve. The reserve consists of mature broadleaf woodland and cliffs below which are formed from some of the oldest sedimentary rocks exposed in the South West of England. The inaccessible cliffs provide nesting sites for seabirds such as fulmars and gulls, and sea caves in the bay provide haul-out sites for grey seals. Near the exposed clifftop, the woodland consists of salt-tolerant blackthorn and hawthorn. On the lower slopes, in the lee of Black Head, it is mostly comprised of Sycamore and Ash with some Ivy and Holly growing beneath the canopy.

  13. Turn right onto the track and follow it to a junction of tracks with a lane. Bear right onto the lane and follow it uphill past the sign for the coast path and onwards for about a quarter of a mile until you reach a sharp bend with a pedestrian gate on the right.

    As you walk along the lane, before you reach the bend, you pass a gateway on the right from which there is a spectacular view over St Austell Bay.

  14. Go through the pedestrian gate on the left of the farm gate on your right. Follow the right hedge of the field to the corner and continue following the right hedge for another 10 metres to reach a pedestrian gate.

    The sunny, well-drained fields here are often used for arable crops.

    Cereal crops such as wheat and barley grow by using the energy obtained by photosynthesis to produce a chemical that reacts with carbon dioxide from the air. A problem for these plants is that as the temperature increases, this chemical is more prone to react with oxygen in the air instead of carbon dioxide. This is the main reason that these crops don't do well in tropical climates and are farmed at temperate latitudes such as in Britain. Maize uses a different chemical reaction to extract carbon dioxide from the air which is more resilient to higher temperatures and also allows these plants to lose less water through their leaves. This allows them to grow in hotter, drier climates such as the southern United States.

  15. Go through the gate and bear left across the field, heading towards the point where the two power lines converge on a post. As you approach, head to the post immediately to the right of the one with the junction box. As you approach more closely, you'll see a kissing gate in the hedge beneath the post.

    In fields with crops where the footpath doesn't run along the edge, if there is a well-trodden path then follow this to avoid trampling any more of the crops. If there appears to be no path through the crops then you do have a right to walk through the crop but stick as close as possible to the line of the path to avoid damaging any more of the crop than strictly necessary. Alternatively, you can follow around the edges of the field to avoid trudging through the crop.

  16. Go through the gate and cross the field towards the farm gate opposite. As you approach, head for the pedestrian gate to the right of the farm gate.

    The hedge that you cross into the field is the remains of Castle Gotha.

    Castle Gotha was a small oval-shaped settlement with a bank and ditch around it. Most of this has been ploughed away but a small section of the bank remains as the hedge between fields. Excavations have shown that the site was occupied in the Iron Age from the Second Century BC to the Second Century AD, and timber huts were originally located against the ramparts. The name of the settlement is from the Cornish word gov, meaning "blacksmith" and during excavations within the sites of the huts, metalworking remains were found. These included pits, hearths, a stone mould for casting brooches and the remains of a larger mould embedded in the floor. The larger mould is thought either to be an ingot mould or possibly for casting sheet metal.

  17. Go through the gate and turn left onto the lane. Follow the lane to a crossroads.
  18. Turn right, signposted to Towan, and follow the road to reach Towan Barn.

    It is thought that the Sawle family of Penrice arrived initially with William the Conqueror and began with an estate based around a manor at Towan, recorded in the Domesday Book, where the two farms are now located. In one of the fields is a holy well, and a chapel once stood nearby. By the English Civil War, the Sawle Family were living in Penrice House and this continued into the 20th Century. The family lost their only male heir in the First World War, and Mrs Cobbold Sawle, the last in the line, died in 1971. In her will, she left Penrice House and much of the estate’s wealth to establish a rest home for the elderly.

  19. From Towan Barn, follow the lane along the fence and then continue ahead towards the farmyard. As you enter the farmyard, bear right to a track running along the right-hand side of all the buildings, and follow this to a gate beside the last barn.

    Towan Farm was first recorded in 1086 as Bewintone. The "tone" in the name is thought to be from the Old English for farm (tun). The "bewin" has been interpreted as originating from the Cornish word towan but since this is the word for "sand dune" and the farm is inland and in a coastal area with no sand dunes, this could well be an error. It's possible that "bewin" was simply the name of the chap who owned the farm.

  20. Go through the gate and follow the track ahead to reach a grassy track leading off to the right, just before the main track goes through a gate.

    Since the 1960s, consumption of milk in the UK has fallen from around 5 pints per person per week to around 3. The recent rise in popularity of veganism has also contributed to a drop in demand for dairy products. However, these downward trends have been partly offset by milk solids used in processed foods including chocolate and also a growth in cheese consumption in recent years.

  21. Turn right down the track and follow it through the woods until you reach a Woodland Trust waymark on the left, just before the track bends.

    As well as attracting insects, the brightly coloured foxglove flowers serve as a warning for animals that the plants contain toxins. All parts of the plant can cause a range of ill-effects in humans from nausea to heart and kidney problems which can be fatal.

    Young squirrels suffer a high mortality rate in the wild and less than one in three make it to adulthood. The ones that do, live on average for about 6 years, although a lucky one can live to about 12 years old. In captivity, where there are neither predators, cars nor cold winters to contend with, they can reach 20 years old.

  22. At the bend, turn left up the path with the green Woodland Trust sign and follow it just a few paces to a wooden pole beside the steps, where it meets another path running downhill to the right. Turn right onto this and follow it until it ends on a gravel path.

    The Woodland Trust was founded in 1972 and is dedicated to providing a UK rich in native woods and trees. They summarise themselves as "the RSPCA of trees" and have set themselves the ambitious target of doubling native tree cover throughout the UK over the next 50 years. They now look after more than 1,100 woods and over 110 Sites of Special Scientific Interest and are committed to providing free public access wherever possible.

  23. Turn left onto the path and then almost immediately bear right down a path leading down into the valley. Follow the path until it meets several other paths at the bottom of the valley.

    During the 18th and 19th Centuries, there were two tin streaming works in the Pentewan Valley. The one towards the bottom of the valley was known as Happy-Union and one further upstream was known as Wheal Virgin. During these excavation processes, they found human remains with charcoal and ash, possibly from Bronze Age burials and bones of animals "of a different description from any now known in Britain". At Wheal Virgin, a tankard was also found from late Roman times made from yew wood and metal bands of a copper alloy. This is now on display at the Royal Cornwall Museum in Truro.

  24. When you reach the bottom, take the main path on the right and follow this a short distance to a junction with another path with a Woodland Trust waymark on the left. Turn right and follow the path to another junction of paths.

    The first method to extract tin was known as "tin streaming" which reached its peak in the 12th Century, though continued until the mid 20th Century.

    Alluvial deposits occurred where a river had eroded the tiny crystals out of mineral veins. Due to tin being so heavy, the crystals had become concentrated on the bottom of the stream as the lighter rocks around them were washed away. Over time these deposits were buried in gravel and sand, and eventually soil.

    Using quite elaborate banks and channels, the river was diverted to wash away the soil and gravel, leaving the heavy tin-rich rocks behind which could be dug out once the river was diverted away.

    One side-effect of all this industry was that the topsoil, sand and gravel washed downriver caused the silting of many river estuaries and once-thriving mediaeval river ports literally dried up and were superseded by sea ports.

    Once the relatively rich alluvial deposits had been used up, mostly by the 18th Century, mineral veins were instead mined directly.

  25. At the junction, turn left and follow the path to reach a wooden barrier just before the car park.

    National Cycle Route 3 runs 338 miles from Bristol to Land's End. The route is a mixture of lanes, byways and some tracks not open to road traffic including the upper section of the Camel Trail from Wenfordbridge to Dunmere.

  26. Bear left onto the cycle track and follow it along the fence beside the car park, then follow either track alongside the river or the path along the top of the embankment alongside. Continue alongside the river to where the track departs from the river and turns into the woods.

    The Pentewan Valley Trail runs along the trackbed of an old railway. This was originally built as a horse-drawn tramway to transport china clay from St Austell to the new port at Pentewan which was completed in 1826. The line opened in 1829 and used gravity to transport the loaded wagons down the incline from St Austell and then horses to pull them along the flat section to Pentewan, and to return the empty wagons.

    In 1874, plans were made to upgrade the line to a railway with steam locomotives. Although the track strengthening had been implemented, shortly after this, a strategic decision was taken by Great Western Railway to direct its china clay traffic to Fowey. By 1877, the shipments were dwindling and by 1880 the operation became unprofitable. However a boom followed only two years later and the line continued until the First World War. The track was the same gauge as that used to service the trenches in France and both the track and locomotives were acquired by the War Department.

  27. Where the track turns left to go into the woods, keep right on the small path along the river and follow it through the gap next to the gate. Follow the path alongside the river until it eventually brings you back into the woods at a junction of paths with three tall trees and a granite post between them, with Pentewan Cycle Hire to your right.

    The St Austell River is also known as the White River due to the china clay that colours it and was heavily modified during the Industrial Revolution so that the lower parts of it now resemble a canal. Habitat improvement work is being done on the river as part of the South Cornwall River Improvement Project.

    The South Cornwall River Improvement Project is a partnership programme lead by the Westcountry Rivers Trust, and is aimed at improving the river habitats around St Austell Bay. The project focuses on both reduction of river pollution and habitat improvement particularly on the lower sections of the St Austell and Par rivers which have been heavily modified and straightened. One of the major objectives of the project has been the reconnection of the St Austell River's major tributary, the Polgooth river, which was previously isolated through a series of culverts that fish such as trout and salmon would not swim through.

  28. Turn right to pass the cycle hire shed. Follow the track to reach the lane.

    The buildings on the opposite side of the river were originally a bone mill.

    Bone mills used the power from a waterwheel to crush animal bones and produce bonemeal. The bonemeal was primarily used as a fertiliser to release phosphorus into the soil, which is a vital mineral for healthy crops. In the 20th century, fertilisers based on phosphate minerals, which could be mined cheaply, made bone mills uneconomical. However, the known phosphate reserves are expected to run out within a few decades and so organic phosphorus sources such as animal bones, and even urine, may become increasingly important for farmers.

  29. Turn left onto the lane and follow it around the bend to return to the car park.

    The metal sluice gate in the garden just after the bridge is a remnant from the system of reservoirs used to flush out the harbour.

    The series of 4 reservoirs above Pentewan were used to collect water both from the stream running along the back of the valley and the St Austell River. These were controlled with numerous sluice gates at the entrance to the reservoirs and between them. The body of water was periodically released to flush sediment out of the harbour and the shipping channels approaching it. The sequence of reservoirs and sluices allowed the water to be collected from whichever was the cleaner of the two sources to ensure that the water being released into the harbour was itself free from sediment.

Chestnut trees deciduous but when in leaf, are recognisable by their large, long leaves with serrated edges. In September and October they can also be recognised by the nut cases which are spiky all over (conkers have infrequent spikes with bald areas in between) and the spikes are sharp.

The chestnut tree originated in Sardinia and there is evidence of its cultivation by humans from around 2000 BC. It was introduced into Britain by the Romans who planted chestnut trees on their campaigns to provide an easily stored and transported source of food for their troops.

In England, the chestnut was originally known as the chesten nut. Both this and the modern French word châtaigne descend from the Old French word chastain.

Unlike many nuts which are designed to last through the winter and then germinate in the spring, chestnuts germinate in the autumn and waste no time putting down some roots. The leaves and stem follow in the spring and their established root system gives these a head start.

Since chestnuts don't need to hang around for a long time on the ground, they are nutritionally more similar to a cereal - containing principally starch and sugars - than a typical nut. They contain very little fat and are consequently much less calorific than other nuts: the kernels contain around a third of the calories of a similar weight of other nuts.

The size of the nuts from wild British chestnut trees is quite variable but the largest rival the nuts sold in supermarkets. Nuts that are very flat or less than the girth of your little finger are not worth harvesting; anything bigger is viable. A painless way to extract the nuts is to grip the husk between your feet and rub it between your boots or against the ground. This saves having to handle the spiky husks as the spikes are very sharp and tend to break off under the skin to leave behind splinters. Often the husks contain one (fairly round) large nut surrounded by several small, flat nuts, so it's worth squeezing out quite a few husks to get the larger nuts. Discard any nuts with holes in (as they will contain maggots) or that are very dark in colour - the fresher ones will be "chestnut" brown rather than dark brown.

To roast chestnuts, prick each of your chestnuts with a skewer or slit the shell with a knife - this is vital to stop them exploding (and disappearing into dust). Bake them in a hot oven for at least 10 minutes. Wild chestnuts are harder to shell than the shop-bought variety as the shells are much thinner and the nuts are often smaller. An easier way to separate the edible part from the shell is to simply slice the shell in half and then scoop out the contents with the point of a knife blade. Also this way, the bitter pith covering the outside of the nut is left behind in the shell. The contents of the nut should be fluffy and pale yellow; discard any that are brown. Separating the flesh from the shells is a fairly tedious process, but with a few friends armed with large cups of tea, a formidable amount of chestnut can be extracted which can be used to make stuffings, soups or whizzed into flour and added to bread recipes. It also freezes nicely so it can be stored up for Christmas recipes.

Compared to many native trees, the beech colonised Great Britain relatively recently, after the last Ice Age around 10,000 years ago. Beech trees have a shallow root system and are therefore often found in areas where water is plentiful such as near rivers. In the 17th and 18th Centuries, tall, stately beech trees were very fashionable in the estates of wealthy landowners and many mature beech woodlands today are the result of 18th Century parkland landscaping projects.

Beech trees can live up to 400 years but the normal range is 150-250 years. Beech trees respond well to pruning and the lifetime of the tree is extended when the tree is pollarded. This was once a common practice and involves cutting all the stems back to a height of about 6ft during the winter when the tree is dormant. The 6ft starting point kept the fresh new growth out of the range of grazing animals. When allowed to grow to full size, a beech tree can reach 80ft tall with a trunk diameter of around 3ft.

The word "beech" is thought to have the same origins as "book" as beech (most probably the bark) was used as a writing material in which to carve runes by Germanic societies before the development of paper. This is still apparent in modern German where the word for "book" is buch and "beech tree" is buche.

The fruit of the beech tree is known as "mast" or, less cryptically, "beechnuts" and these are not produced until the tree is 40-60 years old. The small triangular nuts are encased in spiky husks which split and drop from the trees from late August to early October. The kernels of these are edible and are similar to hazelnuts. They were once used as a source of flour, which was ground after the tannins had been leached out by soaking them in water. If you find them too bitter, you might want to try this trick, although toasting them in a hot pan is also a good option.

Young beech leaves can be used as a salad vegetable, which are described as being similar to a mild cabbage, though much softer in texture. Older leaves are a bit chewy, as you'd expect.

Beech bark is very delicate and does not heal easily. Consequently some graffiti carved in beech trees is still present from more than a century ago. This is a practice that should be strongly discouraged as it permanently weakens the tree, making attack by insects more likely which can prematurely end its life.

Beechwood ageing is used in the production of Budweiser beer but beech is not the source of flavour. In fact beechwood has a fairly neutral flavour and in the brewing process it is pretreated with baking soda to remove even this. The relatively inert strips of wood are then added to the fermentation vessel where they increase the surface area available for yeast. It is the contact with yeast that produces the flavour in the beer, not the beech itself.

Beechnuts can be used very effectively as a thrifty alternative to pine kernels to make pesto. Collect one trouser pocketful of beechnuts. Shell them over a large cup of tea with a friend, toast the kernels over a medium heat in a dry pan, then grind with a pestle and mortar (surprisingly easy once toasted). Chop 4 sprigs of basil each about the size of your hand - roughly half a supermarket pack. Add to this a finely chopped small clove of garlic and a good pinch of salt and freshly ground black pepper. Then shave (with a peeler) or grate a lump about the size of the end of your thumb of some hard salty cheese such as Pecorino or Parmesan (a supermarket basic range imitation will do fine). Finally add a good slug of extra virgin olive oil and it's time to say "proper job". It makes a ramekin full which doesn't seem a lot but it is so packed with flavour that it goes a surprisingly long way.

Robins are able to hover like kingfishers and hummingbirds and use this skill when feeding from bird feeders, which they are unable to cling to.

Robins are also able to see magnetic fields. Receptors in their eyes make magnetic fields appear as patterns of light or colour which allows them to use the Earth's magnetic field for navigation. They only seem to use their right eye for this as the left half of their brain (linked to the right eye) does the processing.

Unlike many birds that just sing in spring, robins sing nearly all year round. In fact during winter if you hear birdsong, it's most likely to be a robin. Despite how cute robins look, they are actually very territorial and the chirp is an aggressive warning to any would-be intruders not to even think of trying it. When robins don't sing, this a sign that their body fat reserves are low and they are conserving what little they have left until food becomes more plentiful.

The tradition of robins on Christmas cards is thought to arise from Victorian postmen wearing red jackets. Consequently they were nicknamed Robins.

The Cornish name for the bird is rudhek from rudh = "red" (in Cornish, "dh" is pronounced like the "th" in "with"). Cornish place names like Bedruthan, Ruthern and Redruth are all based on the colour red.

For such a widespread tree, the oak is surprisingly inefficient at reproducing naturally. It can take 50 years before the tree has its first crop of acorns and even then, the overwhelming majority of the acorns that it drops are eaten by animals or simply rot on the ground. Squirrels play an important part by burying acorns and occasionally forgetting a few which have a much better chance of growing than on the surface.

Sea Trout have a very similar life-cycle to Salmon, being born in a river, migrating to the ocean to feed and then returning to the river to spawn. As with Salmon, they do not feed once they enter freshwater and after spawning they are susceptible to disease. It is not unusual to see them with fungal growths in early winter, but as long as these infections aren't too major, the trout return to the sea where they recover and return to spawn again.

What is intriguing is that Sea Trout are exactly the same species as Brown Trout, which live all their lives in a river. It seems to be that if there isn't enough food, young trout undergo "the change" (known as smoulting) in which their physiology permanently alters for an existence in saltwater, they change colour to silver, and they head off to live in the sea.

The Westcountry Rivers Trust began life in a meeting in a Devon pub in 1994 and was set up as a charity in 1995 to protect and improve the Westcountry's rivers and streams. It was initially a small grassroots charity staffed entirely by volunteers and was then run from the home of its first employee.

In 2001 an umbrella organisation was set up to coordinate the work of four regional rivers trusts (including the WRT) and is now simply known as the Rivers Trust. The 4 founding members have been joined by another 53 that now cover all of Wales, most of England and some parts of Scotland and Ireland.

Himalayan Balsam is a tall plant with very pretty pink flowers that can often be seen lining footpaths in the summer and early autumn. It was introduced as an ornamental species in 1839 and unfortunately the plant is now a major ecological problem. It can grow from a seed to 9ft high in a few months, forming dense thickets and wiping out other plant species. It is also extremely invasive as the seed pods open explosively, launching around 800 seeds per plant up to 7 metres and the seeds are also adapted to travel by water. It is a nuisance on riverbanks as its roots are shallow and allow the sediment to become easily eroded into the river. It can be identified by its bright pink flowers and it has a characteristic sweet smell.

Rosebay willowherb is a tall plant with a spike of pink flowers in late summer which can often be seen beside paths and tracks. Their long leaves have a distinctive thin, white vein along the centre.

The name "rosebay" dates from at least Tudor times and is thought to be based on loose resemblances of the leaves to bay leaves and the flowers to wild roses. The overall family are also known as "willowherbs" due to the resemblance of the leaves to willow leaves. The two names have since been brought together resulting in the slightly confusing duplicate description of the leaf shape.

Rosebay willowherb is known as fireweed in USA as it's found on burnt sites after forest fires. For similar reasons it was known as London's Ruin after the Great Fire. In the Second World War it was also known as bombweed due to its rapid colonisation of bomb craters.

It is a pioneer species which is good at colonising disturbed ground as its seeds travel long distances in the wind and remain viable in the soil for many years. It was considered a rare species in Britain in the 18th century but spread along the corridors cleared for railways in Victorian times.

The large black birds nesting on offshore rocks, known colloquially as the cormorant and shag, are two birds of the same family and to the untrained eye look pretty similar. The origin of the name "shag" is a crest that this species has on top of its head and the cormorant doesn't. The cormorant is the larger of the two birds with a whiter throat. The shag's throat is yellow, and mature shags have a metallic green sheen on their feathers which cormorants lack.

The beach at Pentewan is owned by the holiday park but is open to the public. There's a sandy beach at all states of the tide and is relatively sheltered as it faces east into St Austell bay away from prevailing winds and has headlands either side. The St Austell River divides the beach. The small area to the left can be accessed via the old harbour. The larger area to the right of the river is accessed via the holiday park. A bridge crosses the river into the holiday park near the lock gates of the old harbour.