Portal de Turismo de Castilla y León

Welcome to the "Riberas de Castronuño y Vega del Duero" Park House.

As in the rest of the houses of the park spread throughout the Castilla y León region, it is the recommended gateway to these natural areas. Here, information on emblematic species and habitats of these locations is provided to facilitate the identification and highlight their cultural and natural heritage, while promoting the conservation and appreciation of biodiversity and cultural heritage.

The house is located in the upper part of the village next to the Romanesque church of Santa María del Castillo, which dates back to the 12th century and is surrounded by the chimneys of the traditional underground cellars dug into the ground.

The house is located at the top of La Muela in the municipality of Castronuño. Did you know that the village of Castronuño originated as a defensive point on the Duero River in the 11th century? In the 15th century, in the war for the succession to the throne between the Catholic Monarchs and Joanna of Castile "La Beltraneja", the municipality sided with Joanna of Castile and was besieged for eleven months. Their surrender put an end to the war and also to the ramparts, which were demolished.

The Riberas de Castronuño and Vega del Duero Park House has glass windows overlooking the Duero River and the landscapes of the region. Here you can also find a permanent exhibition and a remote video recording system that allows real-time observation of the fauna present in the Reserve.

The Riberas de Castronuño and Vega del Duero Reserve covers the towns of Castronuño, Pollos, Torrecilla de la Abadesa, and Tordesillas, with an area of 8,420 hectares.

The main artery of the Reserve is the Duero River, which crosses the area from east to west. The retention of the waters of the Duero River in the territory of Castronuño, through the construction of the San José reservoir in the 1940s, led to the creation of this Nature Reserve. The river was widened for thirteen kilometres, which had a significant impact on the riverbank vegetation. The intermediate section that was created is occupied by reeds.

These plants need moisture and moderate heat and require nutrient-rich soil, making them a good indicator of soil richness. Reeds live on the margins of marshes, lagoons, and riverbanks with slow-moving waters, forming dense communities known as reedbeds, which are very important for ecosystems because this is where many water birds live and nest. Their leaves are elongated and lanceolate, in other words, they are lance-shaped, and their spikes form very characteristic feathery plumes.

Before the dam was built, only a few reed beds separated the river from the forest. However, the dam caused it to widen, especially in the Castronuño area, creating an important habitat for purple herons, kingfishers, egrets, and marsh harriers. The reservoir is an important ornithological site in Castilla y León for breeding birds. It’s also a place for migratory birds to rest and reorient their flight during their long journey.

Following this reedbed, irrigated fields are cultivated, mainly alfalfa and corn, which give way to yellow cereal fields, dotted with holm oak groves.

In addition, in this area, the moors and sedimentary plains stand out. There are rainfed and irrigated crops, holm oak forests, and riparian forests. The diversity of the landscape means that there is also a great diversity of birds.

The Nature Reserve is divided into different zones according to their levels of protection. The Reserve is the area of greatest environmental protection, where the most diverse habitats are found. Then, depending on their environmental quality, there are zones that allow different human activities or land uses, such as what we call "limited use one," "limited use two," "compatible use" and "general use" area. In these areas there is agricultural land, extensive, or intensive livestock farming, through which the Reserve's trails run, as well as the associated towns and industries.

The emblem of the Park House is a circle with a purple heron's head and a reed stalk with its plumes, as these are the two most representative species of the area.

The purple heron is a very slender bird, with an extraordinarily slender silhouette. In flight, it adopts a posture by tucking in its neck, its wings are curved and its outstretched legs protrude below the end of the tail. It is smaller and darker in colour than the grey heron.

As for the reed, it is a plant that grows from rhizomes, which are submerged stems, forming long, flexible canes, with lanceolate or spear-shaped leaves. At the top of the stems, flowers appear in summer or autumn, forming plumes.

In the Nature Reserve, over 200 species of birds have been recorded, such as the reed warbler and the great crested grebe, which find not only food, but also shelter, protection and material for building their nests in the reed beds.

Another important bird is the marsh harrier, a medium-sized bird of prey that inhabits wetlands. It is an opportunistic hunter that feeds on a wide variety of prey, including fish, amphibians, reptiles, birds, and small mammals. It is listed as a species of "Least Concern" on the IUCN Red List, but its population is declining in some areas. It has a wingspan about 120 centimetres, with a robust body and long, narrow wings. Its plumage is dark brown in general, with a lighter shade on the head and neck. It has a large, rounded head with a long, curved beak. Its eyes are large and yellow. Its legs are long and yellow, with black claws.

The fragility and relevance of the ecosystems generated by the construction of the dam led to the protection of the area as a Nature Reserve. The dam was erected to form the San José reservoir, with the dual purpose of generating electricity through a hydroelectric plant and building two irrigation canals: the Toro canal and the San José canal, which carry water to areas far from the river. The fact that the dam has led to a marked increase in biodiversity in the surrounding area is a positive effect of its construction.

One of the nesting boxes has a large entrance, no roof and is full of feathers. Can you imagine how they build this entrance?

The architect is a woodpecker, in this case, a great spotted woodpecker, which, on discovering the perfect little hole in the nesting box, pecked at it and made it bigger so that it could get in. Once it managed to get into the nesting box, it saw that it is too small to nest in and had no insects, so it left, leaving the nesting box useless. Great spotted woodpeckers are insectivorous birds, with strong beaks, a reinforced skull and strong legs and tail that they use to rest on the trunk for extra strength when pecking.

The main function of these nest boxes is to encourage the nesting of small insectivorous birds, such as Eurasian blue tits, finches, fringilla or European robins. Sometimes, however, wasps take over the box and make it their home.

On the trunk, you can see a woodpecker’s nest. The woodpecker fills its nest with soft material found in the environment, like moss and poplar fluff, which provides a bed for its eggs and chicks. As a curious fact, if the great spotted woodpecker were to find sheep nearby, they will use their wool to pad the nest.

It is common to hear the rhythmic sound of the great spotted woodpecker, which can reach up to twenty-two times per minute. Like all woodpeckers, they use pecking for nest building, foraging, and to attract the attention of females during courtship.

In the theatre there are special nesting boxes for bats. In Castilla y León, more than twenty-one species of bats have been identified, all of which are protected.

Bats are the only flying mammals in the world. They are small and light animals, varying in weight and size from species to species.

Bats bodies are adapted to flight. Their wings are formed by a membrane that extends from the fingers to the toes. This membrane is reinforced by bones and muscles that give it rigidity and strength. They have a large head with an elongated snout, small eyes with night vision and highly developed hearing, which allows them to orient themselves and capture their prey.

Bats feed on a wide variety of prey, including insects, fruits, flower nectar, and small fish, mammals and reptiles. Insectivorous species are the most numerous and play an important role in controlling insect populations. They are nocturnal animals that hunt at dusk. Their flight is silent and agile, allowing them to approach their prey undetected.

Here you can observe a sample of the tracks left by the animals that live in the area, for instance, moults from Montpellier snakes and ladder snakes, pellets, nests, nibbled almonds, feathers, and eggs. There are also animal remains such as skulls and antlers. All this demonstrates the existence of a great biodiversity, which, although most of the time invisible to humans, leaves clues to their presence in the area.

You can also find pieces of charcoal from the Mediterranean scrubland, where charcoal makers used to make charcoal from holm oak wood.

The work of the charcoal maker was a hard and laborious activity dating back to ancient times. Charcoal makers were responsible for the extraction and production of charcoal, a fuel used for cooking, heating, and lighting. The charcoal-making process began with the selection of suitable wood, usually oak, holm oak, or cork oak. The wood was cut into approximately metre-long logs and transported to the place where the charcoal was to be made.

Once on site, the logs were stacked in a pyramid shape. Stacking was carried out carefully so that the wood was well compacted. A layer of earth or dry leaves was then placed on top of the wood.

The next step was to light the fire. The fire was placed in the centre of the pyramid and left to spread slowly for days.

Once the wood was charred, it was stored in sacks and transported to the markets.

The charcoal maker trade largely disappeared in the 20th century, due to the development of coal mining. However, there are still some charcoal makers who continue to work in the Mediterranean forest, maintaining an ancestral tradition.

If you carry on, you can find a room with an interactive game, a map and information panels describing the natural areas of Castilla y León.

The Montaña Palentina area, declared a Nature Reserve in 2000 for its natural, scenic, fauna, and botanical value, is the natural habitat of the brown bear and the Eurasian capercaillie. The vegetation includes oaks, beeches, holm oaks, and junipers. With a complex geology, it has an extremely modelled relief, the result of the action of both karst and glacial phenomena, which is reflected in cirques, valleys, and lagoons, such as the Lomas Lagoon, the Ves Lagoon, and the Curavacas Well.

With this information, you are welcome to discover other landscapes in the community.

Go on to the "Reserve Observatory" booth. Here you will find a screen where the images of the Nature Reserve recorded by the live camera are streamed.

This hut is one of the most important resources of the Park House, thanks to the live camera, located in the reedbed on the river bank, within the Nature Reserve zone, which is fully protected. The camera is operated by turning the knob on the pedestal in the centre of the room.

The camera makes it possible to follow the animals living in the river and the reedbed in real time. It has continuous recording and night vision. With these recordings, an important collection of sightings is collected, which can be shown during visits. Otters, purple herons, and nesting grebes, among others, have been recorded.

The camera has recorded how they pair up and incubate eggs, how they start feeding the chicks when they are small and how fast they grow. The camera has also witnessed the creation of stork's nests, kingfishers diving, birds of prey perched in the trees, turtles and crabs.

Climb to the top floor.

Upstairs, to the right of the room , there is a map and an interactive display summarising the characteristics of this natural space, which are the same as those on display on the ground floor.

This sign shows the main ecosystems of the Nature Reserve, with the river as the main axis of the landscape and the diversity of the environment. The Duero River is the aquatic ecosystem and, next to it, the riparian vegetation. Riverside forests, also called gallery forests or copses, are deciduous forests that grow on both sides of rivers. They are characterised by the presence of plant species that need the humidity of the river to survive. They are important for the environment, as they are refuge areas for wildlife, provide shade and coolness on river banks and help regulate water flow.

This is followed by the reedbed, which is often flooded. As you move away from the river, the biodiversity changes and the landscape becomes Mediterranean forest, characterised by the presence of pines and holm oaks, as well as rainfed crops, which are home to species such as great bustards, little bustards, and stone curlews.

In this Mediterranean area, species other than those closest to the river coexist, such as the badger, the dormouse, the Iberian eagle, and the deer. As a curious fact, it is worth noting that most of this area of Mediterranean forest belongs to private estates dedicated to big game hunting.

These Mediterranean forests play an important role in the environment, as they are refuge areas for wildlife, help regulate the water cycle and protect the soil from erosion.

In the upper section of the panel, you can interact with the magnifying glass that can be found on the pedestal and discover a butterfly wing, a feather, a millipede, a fly, or whatever is on display at the moment.

Initially, this magnifying glass was designed to observe the micro-organisms present in the river water, but the intensity of the light was so strong that it dried and heated the water, causing the micro-organisms to die.

Below, you will find steppe birds such as the stone-curlew, great bustard, little bustard, and the calandra lark.

These birds are found in areas with dry climates and sparse vegetation and can survive extreme conditions.

These birds are large to medium-sized, with long, pointed wings, allowing them to fly long distances in search of food and water. They also have dull-coloured plumage, which helps them camouflage in the environment.

Steppe birds feed on a wide variety of prey, including seeds, fruits, and small mammals, and help control insect populations.

Steppe birds are threatened by human activity. Agriculture, livestock farming, and urban planning are reducing the habitat of these birds.

Last of all, you can see a panel with plants from the reedbed, thus completing an interactive experience that combines information on birds and flora specific to the natural environment.

Then, in the interactive feature, you can discover which animals live in these forests in both summer and winter and match photos of raptors with the silhouettes of raptors in flight.

It is important to note that the most reliable method of identifying raptors is to look at their silhouette as they fly above you, usually against the light. Experts also analyse the flight, the environment and its colours.

This panel depicts the silhouettes of a short-toed snake eagle, a goshawk, a black kite, and a booted eagle.

They are all diurnal birds of prey; therefore, they hunt during the day. They have sharp claws and a curved beak that they use to capture and kill their prey.

In terms of physical characteristics, all these birds are relatively large, with long wings and a relatively short tail. They also have dark-coloured plumage that helps them blend into their environment.

Additionally, red kites, buzzards, griffon vultures, some black vultures, and the Iberian imperial eagle are common in this area.

Continue to the window. From there, you can see the church of Santa María del Castillo, built in the mid-13th century in a late Romanesque style with Gothic touches. Interestingly, if you look closely, the roof of the church does not have tiles but stone slabs.

When you reach the hall, you will discover panels with old black and white photos of the people who have lived on the banks of the Duero and who have based their existence on the river. These images have been donated by the residents of these villages, who are proud to have this centre.

In the past, the farm labourers worked on the estates, charring the holm oak, working the land, tending the herds, and hunting rabbits. As a curious fact, each labourer could take home half a rabbit out of every ten he hunted and the rest were sold. On one occasion, 40,000 rabbits were sent to Madrid.

There were also those who worked on the Duero. The fishermen used to go down to the river bank on mules to where they moored their boats in the place still known today as the harbour. The catch was sold in villages, sometimes far away from here.

Another important post was that of the boatmen, who were responsible for ferrying labourers and flocks of sheep in large barges from one shore to the other. On them, hundreds of people crossed the river daily for years.

The posters capture festive moments, landscapes, bicycle races, slaughter celebrations, children in first communion attire, and various aspects of the life of these neighbours. It is worth noting the photo of the landscape before the construction of the dam.

Carry on until you reach the viewpoint of the Park House. Here, the extensive ecosystem of the Mediterranean forest opens up before you. In the distance, the wind farms of San Pelayo and Torrelobatón can be seen. To your left, you can see the territories of the municipality of Toro, among vineyards, while the higher slopes to your right are part of the territory of Tordesillas. From this point, you can see how Castronuño is located on one of the meanders of the Duero River. Did you know that this curve is considered one of the largest meanders in Europe?

This part is a middle section of the river, flowing from the right to the left, where the velocity of the river is not very high and carries a considerable amount of suspended matter. Because of this, you won't find trout or salmon in these waters, but rather carp and barbel. On the opposite bank, at the height of the railway bridge, there is a sport fishing area with sixty stalls, where championships are held in collaboration with national fishing associations and federations.

The Nature Reserve undergoes changes throughout the year, especially in the riparian vegetation, which is mostly deciduous, showing a more evident change than other species such as pines and holm oaks. During the summer season, the reedbed becomes stronger and takes on a more greenish hue.

In addition to the natural landscape, the surrounding group of chimneys, which correspond to the cellars excavated on the top of La Muela, is also striking.

In front of the window, you will find excrement, pellets, and footprints.

Pellets are compact masses of non-digestible remains such as bones, hairs, feathers, and even insect exoskeletons, which certain birds, such as nocturnal raptors, regurgitate after ingesting their prey.

The pellets are a crucial source of information on bird feeding, as birds eject them with their beaks. All birds that eat micro-mammals, such as mice, voles, or fish, ingest parts that are not well digested. These parts are regurgitated through the beak in the form of hairballs and bones. Thanks to the remains found in the pellets, it is possible to identify the species that regurgitates them. For example, eagle owl pellets are huge, with a diameter of twelve centimetres. Herons, on the other hand, eject pellets composed of scales and spines. These structures provide valuable information about the presence of certain animals, similar to what tracks would do. For instance, the presence of the Algerian mouse in the Nature Reserve is only known thanks to the identification of its jaws in the pellets.

Enter the audio-visual room and take a seat inside the boat. The audio system, projections and a system of fans will create a montage in which you will feel like you are taking a boat ride on the Duero River.

The audio-visual projection brings the visit to an end. The tour of the Nature Reserve is summarised here with a visual and audio explanation.

The "Riberas de Castronuño y Vega del Duero" Park House is an open window to the Nature Reserve, where you can explore the geology, fauna, flora, and history of the area, through models, interactive games, posters and views from the viewpoint that underline the importance of conservation and appreciation for the ecosystems of the Nature Reserve.

When visiting the Nature Reserve, please remember to gather information on the different levels of protection of the areas and safety advice. It is essential to respect and protect the habitat of the Duero River, especially, the reeds and all the native animals.

To conclude, we will read a text by writer Valentín Herrera:

If you have come to Castronuño, to enjoy La Muela,

you will, unintentionally, see great things.

I would like to remember some places to admire

in the village, believe me it’s no dream.

Cuesta, Cartago, Cubillas, and part of La Ribera,

the entire Duero Valley, La Calda, and Las Laderas.

To La Salud fountain we go down for water,

with the jug on our shoulder, our head, or our hip.

From La Salud fountain through to Teso

I walk down to the olive groves and over to the pass.

From the pass to the viewpoint, I climb calmly and happily,

and when I get there, I can’t believe my eyes:

The Mucientes viewpoint is real, not a fairy tale,

enjoying this landscape is an event.

Few places like that can be seen today,

to admire it, you have to come here.

From the Mucientes viewpoint, I go to La Cal furnace

and when I get there, I see something special.

From La Cal furnace, to Peñarrubia I go

to enjoy the scenery if I were to climb to the viewpoint.

Of all these places, which I wanted to mention,

I think there are very few places that can match it today.

At the Nature Reserve House, you can get more information,

they will show you things with great kindness.

And so I want to say goodbye, without ever bidding adieu,

so you come often if you have the chance.

With this audio track, the visit is over. To exit, go back to the entrance or the door at the back of the room, which connects to the room you have reached on this floor. Here, you can use the stairs or the lift to go down to the lobby.

Thank you for your visit.