The Wetland
Classically defined as ‘land covered with shallow water or saturated with water either permanently or temporarily,’ wetlands cover a very wide range of habitats that are closely linked to water: marshes, swamps, bogs, riverbank woodlands, estuaries, ponds and lakes, and damp woodlands. They are often small in size, protected and fragile. They are some of the most biodiverse habitats on the planet. They are characterized by their own specific flora. They perform particular functions and have many beneficial uses, including flood limitation – by slowing the flow of the water, expanding the flood zones and reducing the effects of drought – because these waterlogged terrains are closely linked to the nearby rivers, and will replenish them when the levels are low, which allows the supply of drinking water to be maintained. 
These wetlands are reservoirs of biodiversity as they provide homes for a great many water-loving species of plants and animals, such as amphibians. 
Wetlands are often simply ditches or streams that are fed by waste-water or urban and agricultural run-off. 
They capture the fine soil particles in the waste-water and they transform the nutrients, such as nitrates and phosphates, into carbon storage. 
Wetlands serve as climatic buffer zones, and in urban areas, they significantly reduce the ambient temperature. 
Wetlands, with their often exuberant vegetation, contribute to the diversity of the landscapes, as well as being a place to walk and discover nature. 

The Orchard 
In April 2017, the Mairie of Pibrac signed an agreement with the benevolent society Jardin Nature Pibrac (JNP), giving them the use of an area of about 4,000 m2 in the Tambourettes quarter, to create an orchard for education and the conservation of fruit trees, by planting ancient local varieties. 
The first nine trees were planted in the spring of 2017, and forty-two were planted in the autumn of that year, then six more in spring 2018.  
Each tree is labelled, to teach identification, and to give the visitor details about the variety and its history. 
There are already six information panels about local biodiversity, an educational beehive, an insect hotel and a biodiversity spiral-island. 
This conservation orchard, which serves as a symbol and a demonstration of vegetation diversity, s well as an educational tool, and a way of preserving local heritage, also allows locals and visitors to discover, observe, recognize and compare different species, varieties and cultivars of fruit trees. 
The apple ‘Reinette de Sainte Germaine’ has its place, of course, and advertises the local heritage. 
The site is regularly visited by schoolchildren and amateur gardeners. Along with the Educational Garden, it allows for variety of activities linked to the environment and citizenship. It is also an ideally convivial location. 

The Biodiversity Spiral
The framework for the biodiversity island is in the form of two spirals made from solid oak (class 4), sourced from sustainably managed forests. Oak is said to be able to last for over 15 years in these conditions. The oak planks have been specially made to create harmonious curves, and they have been dug in deeply. 
The spiral has been filled using local earth, sand, vegetable compost, pebbles from the Garonne, roof tiles and slate. This substrate covers four shelters inside the structure. This biodiversity island can accommodate pollinating insects, predatory insects, insects that recycle organic matter, birds, small mammals, amphibians and reptiles. 
When making these refuges, different materials are used to create suitable conditions for reproduction, hibernation, protection, or simply to meet a physiological need: shade, cool air or inversely direct sunlight.  
The refuge cavities are hidden within the structure, and each one has its own entrance. 
At the top of the spiral, there is a cavity made for earth bumblebees, and it is lined with twigs to which the nest can be attached. Various solitary bees find refuge in stems that are hollow or pithy, tied in bundles, and attached to the edge of the spiral. Lizards can enjoy warming themselves on the roof-tiles and by the two slates placed vertically. Amphibians and reptiles can hide in the small hollows at the base of the spiral. The largest internal cavity can provide space for hedgehogs. There is a nest-box for Blue Tits at the top of the tall post. 
The plants have been chosen for their low water consumption and their resilience: 
- Borage, flowering March-November;  
- Lavender, flowering June-August; 
- Rosemary, flowering January-April; 
- Sage, flowering May-October; 
- Mint, flowering July-August; 
- Oregano, flowering July-September; 
- Salad Burnet, flowering June-July; 
- Thyme, flowering May-July; 
- Lemon Thyme, flowering May-July; 
- Verbena, flowering June-October; 

The Educational Beehive  
A beehive is a place where a colony of bees develops. In olden times, it was often a woven basket or a hollow tree trunk. For the past two centuries, bee-keepers have usually been raising bees in wooden hives with moveable frames.  
A bee colony is made up of three different castes: 
 A queen bee, whose lifespan is from two to three years. She is the mother of all the other bees in the colony. She can lay up to 2,000 eggs daily. 
 Female worker bees, who live between one month in the summer and four or five months in winter. They do all the tasks in the hive: building cells, cleaning, feeding larva, protecting, storing the nectar and finally going outside the hive as field bees fetching nectar, pollen or water. In high season, there are about 30,000 worker bees. 
 Male drone bees, whose lifespan is from four to five months. Their main task is to mate with the young queen bees who will establish new colonies. They also participate in the heating and elaboration of the honey. There are between 2,000 and 3,000 males in a colony. At the end of the season, in August, they are expelled from the hive by their sister bees.  
The bees lay wax combs on the frames of the hive composed of perfectly hexagonal cells. At the centre of the frame you find the cells of eggs and larva. They are surrounded by cells containing pollen (for feeding the larva) which are in turn bordered by the stocks of honey.  
A bee-keeper always leaves the honey in the body of the hive as a reserve for the bees. In springtime, however, he installs a ‘super’ on top of the hive where the bees will stock the excess honey which he then collects.  

The Educational Garden 
By an agreement concluded in January 2015, the Mayor of Pibrac allowed the association Jardin Nature Pibrac (JNP) the use of an area of 400 square meters in the Tamborettes sector in order to create an educational garden based on principles of agro-ecology.  
The originators of the project wanted to enable schoolchildren in Pibrac and also JNP members to discover and practice gardening while, in a wider sense, getting them interested in plant life, soil animal life and the environment. The other objective was to allow members of the association to meet regularly in order to share experiences, practice new forms of gardening, ensure up-keep of the garden, attend lectures, participate in workshops and at several other events held throughout the year.  
In January 2017, the surface area was extended to 4000 square meters in order to create an educational orchard of ancient varieties of fruit trees. More recently, a beehive was also installed. 
JNP finances, lays out, plants and manages the Jardin, the orchard and the beehive. 
The remainder of the garden is made up of a pergola, a table, descriptive notice boards on biodiversity and on the beehive, a small pond and finally nests for insects. The workshops held there are presented by an organic market gardener.  
The area is open to the public. Every year, the garden hosts an inter-generational scarecrow competition with participants coming from the local associations, schools, nurseries and EHPAD homes. Young people help with decorating and with some of the lay-out of the garden. JNP ensures conservation of ancient forms of wheat in support of the Pétanielle association. The pumpkins grown in the garden are sold for the benefit of the Téléthon and the Restos du Coeur. 
Conviviality is an important aspect of the educational garden as well as in the other events organized by Jardin Nature Pibrac.  

Birds have existed on earth for hundreds of millions of years. These animals are: bipeds (two feet), oviparous (they lay eggs), endotherms (warm-blooded) and they have feathers. 
There are more than 11,000 species of birds in the world, and they are distributed all over the planet. Birds occupy most ecological niches: banks of rivers and streams, forests, fields, woodland edges, oceans … Some birds are diurnal (active by day), and others are nocturnal (active by night). Birds have adapted to the changing of the seasons, and about half of them have developed a tendency to migrate, the other half remain sedentary. 
The body shape of birds tells us about their way of life: 
- The blackbird’s powerful legs and beak show its capacity for rummaging among the leaves to find its food on the ground. 
- The woodpeckers’ long front toes, with two toes pointing backwards, it’s rigid tail feathers and its very powerful beak, all show us its capacity to climb trees and make holes in the wood. 
- The swift’s slender wings and very short legs indicate its preference for flying. 
Most birds fly. There are three types of flight: 
- Wing Flapping: Some birds need to flap their wings to fly: ducks, passerines, fowl … 
- Hovering: Some birds are able to hover in one place, and some can even fly backwards: falcons, hummingbirds… 
- Gliding: Some birds, once they have taken off, use their wings and rising air currents to glide in flight: raptors, seagulls, petrels … 

The Riverbank Woodland 
Riparian forests are wooded areas that lie along watercourses. On the intensively farmed plains, they become the only corridors for the animals to move along. The woodland lining the banks of the Courbet and the Aussonelle has become the most important passage for birds moving between the Garonne river and the Bouconne forest. 
Riparian forests are always composed of three layers of vegetation: 
- The trees, whose deep roots anchor and strengthen the river banks. Here the commonest species are: Common Alder, Black Poplar, Ash … Very often, these species are replaced and outdone by an invasive species: Robinia pseudo-acacia. One adult alder tree is able to provide a solid anchor for ten or so metres of riverbank. They also enable several bird species to come and nest: Carrion Crow, Rook, Woodpeckers, Jay, Heron, Magpie.  
- The shrubs, with their interlacing branches, help to reduce the speed of the river during flooding, and in this way they reduce erosion. The most common along the Courbet are: Willow, Bramble, Blackthorn, Dogwood and Viburnum. This layer also serves as shelter and nesting habitat for many bird species and several mammals. 
- The herb layer helps to reduce the eroding quality of the water. It is also the most active filter for the retention of sediments and any polluting chemicals. The main types of plant found are: sedges, fescue grasses, rushes, reed canary grass … The tall herbaceous plants provide shelter for Reed Warblers, Mallard Ducks and Moorhens. The steep banks very often contain Coypu burrows, and it is possible to see Otters, which are currently recolonizing the Aussonelle. 
Amongst the areas of intensive agriculture, the riverside woodlands and the grassy strips beside the river are the only defence against pervasive agricultural waste and pesticides. 

A mammal is a vertebrate animal where the mother suckles her young. 
In this woodland, the mammals most frequently seen are: 
- A solitary Roe Deer, often at the forest edge, with its long legs. The male has antlers, renewed once a year. He can by distinguished by his bark of danger, which allows him to raise the alarm of a nearby predator. 
- Wild Boar live in groups most of the time. It is not unusual to see 5 or 10 or more individuals, from the little piglets, with their distinctive coats, to the matriarchal sow. The large males are more usually solitary. 
- Foxes, whose russet coat is easily identifiable, eats mainly small rodents. 
- Squirrels, living in the tree canopy, are the easiest for us to observe. 
- Hedgehogs are mostly nocturnal. You can often see them on the ground in parks, gardens and forest, looking for food. 
- The Mustelids: the Weasel, the smallest European carnivore, 20 cm long and less than 100 grammes; the Stone and Pine Martens, which look like Weasels but are bigger at 45 cm and 1.4 kg; the Polecat, totally brown except its lighter cheek and chin, 45 cm and 1.5 kg. The Badger is the most easily recognisable by its very wide back and the three white stripes on its head – 70 cm long and 20 kg. 
- Moles and Shrews live under ground and eat earthworms, caterpillars, larvae, slugs and many kinds of insects. 
- Bats: Common Pipistrelle, Kuhl’s Pipistrelle, Daubenton’s Bat, Lesser Noctule, Lesser and Greater Horseshoe Bat. 

The Woodland 
A forest is an area of vegetation made up of trees that are either planted or growing naturally, often growing over a shrub layer or herbaceous layer.  
In this region, they are all found either on steep slopes separating river terraces in agricultural use, or on river plains prone to flooding. 
The hillside forests grow on poor, leached soils, composed of ‘graves’ (gravel) and ‘boulbènes’ (fine sandy-clay soils). The forests on the flood plains grow on shallow soils with layers of ‘grep’ (pebbles of different sizes) or ‘marne’ (marl – calcareous clay). The roots cannot easily penetrate these soils. 
The species of trees present along this path, starting with the most common: 
Oak: the commonest being the Sessile Oak on the dry soils; some Pedunculate oaks in the cooler, moister areas, and some Downy Oaks in the most gravelly soil. Then there are Alders on the damp soil, Ash on the dry soil, Robinia pseudo-acacia on the edges, Hornbeam on the deep, moist soil, and also Wild Service Tree. 
The shrub layer is present in the clearings and forest edge, and under the tree canopy, where it forms very thick undergrowth. This means that the woodlands are relatively impenetrable. 
The shrubs found are: Green Heather, Gorse, Ling Heather, Bracken, Blackthorn, Juniper, alder Buckthorn, Dogwood, Bramble, Hawthorn, Wild Rose… 
The herbaceous layer is mainly at the forest edges. It is mainly composed of fescue grass, sedges, orchids, asphodels and lungwort. 
Because of the poor quality of the trees, these woodlands have had few industrial uses. However, from the Middle Ages until quite recent times, they provided the main source of heating houses, and especially bread ovens in this region. This regular usage explains their continued existence. 
The main roles of the forest are: protection of the fauna, carbon storage, climate regulation by reducing temperatures through evapotranspiration, and they have a social role as spaces for recreation and leisure. 

The Row of Oak Trees
There are 800 types of oaks, but only a few species are indigenous to mainland France. Pedunculate, Sessile and Downy Oaks shed their leaves, while Evergreen Oaks, Kermes Oaks and Cork Oaks keep them all year round. 
Some oaks keep their leaves, dry on the branches, throughout the winter; they fall when the buds open in spring. 
Oaks have different male and female flowers on the same tree. 
It is one of the longest-lived of all trees. It starts to produce acorns at around 35 years old. It reaches its maximum acorn production at between 75 and 100 years; at 300 years it becomes a veteran tree, and it can live to 800 years and more. 
The pedunculate oak is so called because the fruit is borne on a long stalk, or peduncle. It is a Eurasian species, living in an Oceanic climate, and it can be found all over France except above 1,300 m in altitude and in the Mediterranean region.  
The nearby Foret de Bouconne is an ancient, relic forest, it once occupied the whole of the bend in the Garonne river from Saint-Gaudens to Montauban. It is still standing today because the gravel soils on which it grows are of no agricultural value. 
The oak is associated with the Jay because its acorns represent about 75% of the Jay’s food. The bird disperses around 5,000 acorns every year, it hides them then forgets them, in soils that are not bare but treeless. Sixty per cent of young oak trees growing wild come from these seeds. The two species are co-evolved: the Oak feeds the Jay and the Jay disperses the acorns. 
Oak wood is the hardest and most durable of European woods. It is used for roof timber, railway sleepers, fine carpentry, stilts for houses, naval construction. The wood is also used for making barrels, due to the quality of its heartwood and the presence of tannins. France produces three quarters of the world’s barrels. And finally, the oak bark supplies the tannin used for tanning leather. 

The Siberian False Elm 
This is a variety of the Ulmaceae family of trees called the Caucasus Elm or False Elm of Siberia (the real elm of Siberia being Ulmus pumila). It is increasingly called in French Zelkova or Zelkoua which comes from the Caucasian word tzelkva. 
The False Elm of Siberia was introduced in Kew in 1760. Some saplings were later brought to France. However, it was not until 1785 in France that the botanist André Michaux, on returning from a mission in Persia, gave a complete description of mature trees observed in the forests of Gilan on the shores of the Caspian Sea (initially an oral description and later in written form under the pen name of Planera Richardi in his Flora boreali Americana, published in 1803). He brought back from Iran seeds and plants gathered in the Gilan forests. The oldest Zelkova carpinifolia in France was brought back from that mission and is to be found in the Jardin des Plantes in Paris.  
The leaves resemble those of the hornbeam (Carpinus) tree, being staggered, jagged, sharp pointed while smaller than those of the Elm as well as being thinner.  
The Caucasian Elm is to be found in the Caucasus and in Northern Iran. 
It is not vulnerable to Dutch elm disease because of its resistant bark which prevents the Scolytes, or Elm Bark Beetle, that ravaged the Elm from nesting on it. Its gold-tainted wood, comparable to that of real elms, is used in cabinet-making. 
It is often used in Bonsai because of its thin branches and the small size of its leaves. In Europe, it is also frequently used as a decorative tree in parks because of its majestic appearance and its perfectly egg-shaped crown.  

Dragonflies are insects belonging to the order of Odonata. They are most often to be found near fresh water habitats, as they need these in which to lay their eggs in and breed. 
The word ‘dragonfly’ is very often used to denote all kinds of Odonata, but actually the Odonata comprises two main sub-orders: the Anisoptera (or dragonflies) and the Zygoptera (or damselfies).  
Damselfies’ front and back wings are the same, and most of them rest with their wings folded over the body. The Lestes family is an exception, that rests with its wings either open or towards the back. They are light, delicate, slender in flight, and always found near water. 
Dragonflies (Anisoptera) have front and back wings that are different, and they rest with their wings spread. They are large-bodies, powerful insects, that can fly very fast, and that can be found far away from water. 
The Odonata’s way of mating is very distinctive, and the couple form what is known as a ‘heart shaped coupling’. The male holds the female behind her head with claspers at the rear of his abdomen, and the female takes the drop of sperm from the second segment of the male’s abdomen, where he has placed it. 
The female lays the eggs beneath the water’s surface. The larvae may remain in the water for between two months and five years, according to the species. They have a carnivorous diet: insect larvae (including mosquitoes), aquatic invertebrates, tadpoles and fish fry. 
The adult, or ‘imago’, is an insect with six legs and two pairs of wings. It will only live for one season. It lies in wait for its prey, very often from the same perch. Its favorite food is flies and mosquitoes. 
There are about fifteen species of Odonata here by the banks of the Courbet. 

Wood-boring insects 
A tree is a living being, and like all living beings, it is born, grows, reproduces and dies. 
The various causes of tree death are: unsuitable soil, (excess water or lime); weather events such as prolonged drought; diseases, especially cryptogamic ones, such as rust or mildew; damage to the roots during building works; and fungi developing on the trees. 
The Cork Oak is also the victim of a multitude of insects, that attack the leaves, (Gypsy moth and Green Oak Tortrix moth); the roots, (white grub Cockchafer larva); and the cork layer, (Cork grub and Cork Ant). There are also wood-boring insects that attack both living and dead wood, such as the Oak Pinhole Borer, the Oak Jewel Beetle, and the Great Capricorn Beetle. 
With its long body, 6 cm excluding antennae, the Great Capricorn (Cerambyx cerdo) can actually destroy trees. The male can be identified by his antennae that are longer than his body; the female’s antennae are never longer than the end of the abdomen. A larva with a healthy appetite can reach a size of 7 to 8 cm long, and it digs galleries the size of its body. 
The insect appears in late May to early June, and it is active in the twilight hours. It flies slowly, its body at 45°, its wing-cases in a V-shape, its antennae in a wide, circular arc. It lives for one or two months, eating only sap from trees and ripe fruit. 
It is more often found on trees that are already weak, (age, disease, severe pollarding, …). It prefers trees that are at the forest edge or isolated.  
Unlike other longhorn beetles, the Great Capricorn attacks living wood, and moreover, it burrows quite deeply. 
This insect is currently protected by law and it is indeed becoming rarer in certain regions. 
Cork Oaks, like many trees, after undergoing physical attacks such as fire or felling, do not die; they can always grow again. 
Under the dead bark, buds will grow that will develop into branches. These buds were dormant on the axil of the leaves, which fell several years ago, or even several centuries ago. 

The Cork Oak 
Cork Oak, ‘Quercus suber’, is a typical tree of the western Mediterranean region: Italy, Tunisia, Algeria, Morocco, Spain, France, and also the eastern part of the Atlantic region: Portugal, Spain and France (Gascony). The oaks present in this region are at the eastern edge of their range within Gascony. 
In Gascony this tree is known as ‘Tarta’, ‘Cors’, or ‘Surrè’. It is a specific variety of cork oak, ‘Quercus suber occidentalis’. Tarta is thought to have given the name to the town of Tartas founded in the 7th or 8th century. It is thought that the species was planted in a scattered way, under Henri IV’s reign, during the first ‘improvements’ to the Landes de Gascogne, the vast heathlands near the Atlantic coast. At the beginning of the 19th century, during the great plantations in the Landes, 20,000 hectares were envisaged for this species. In 1860 there remained about 5,000 hectares, in 1912, 1,000 hectares, especially around Andiran, near Nérac. The winter of 1830 decimated a very large part of the subéraies (cork forests) in the Nérac region. 
In 1646, on the first land register of Pibrac, the Bois de Labarthe is shown as planted with cork (Cork Oak) and holm (Evergreen Oak). This forest was protected by an enclosure wall. These trees must have been planted around 1580 by the Faur family, who owned the land. The family also owned land in the Nérac region, and must have been familiar with growing Cork Oaks. The family also had close links with the French crown, as ambassador and chancellor of Kings Henry III and IV. 
The Cork Oak lives around 150 to 200 years, but its life expectancy canbe up to 300 or even 800 years. 
It is an evergreen tree. 
It is a monoecious tree: it has male flowers on the growth of the current year and female flowers on the growth of at least two years. 
The ‘occidentalis’ variety of Cork Oak resists cold weather better, and it is also unusual in that it flowers both in spring and autumn, so that its autumn acorns are carried until the following summer. It is an alkaline-intolerant tree that prefers poor, dry soils. 

The Heathland
A soil that has formerly been cultivated does not remain fallow for long. It only needs a few decades for it to become a forest. This transition goes through a series of stages. 
Fields of monoculture crops are very productive but very poor in biodiversity: namely, the crop itself and some pioneer weeds that try to survive: Ragweed, Broomrape, Cocklebur, Thorn-Apple, Black Twitch Grass, Common Knotgrass, Rye Grass … Unfortunately, over the last few decades, certain of these pioneer weeds, as well as weeds of cultivation, have become rare or very rare, due to the use of pesticides. 
Once cultivation has ceased, in only a few months a herb layer will burst forth, with the pioneer species listed above, as well as other plants such as Wild Carrot, Grasses, Plantain, Ragworts, Groundsels and Nettles … 
A few years later, the vegetation starts to grow higher and you start to see Elder, Dogwood, Wild Rose, Bramble, Blackthorn … Bramble is a classic pioneer species of uncultivated land. It is very good at enabling honey production, it has excellent fruit, and is also a natural shelter for many different animals. Beneath its lush vegetation and its thorns, it protects the growth of young trees. 
The trees that have germinated and grown naturally, still sparse, can serve as nests for fruit-eating species, which will continue to set seed and make this young forest permanent. If the tree layer finds the conditions suitable for growth, it will end up by depriving all the other layers of light, and they will decline. The forest created in this way is not eternal and if it is left alone, little by little the trees will die and fall, and there will be a new cycle of natural repopulation, which will enrich the biodiversity of the place. 
Heart-shaped Serapias: ‘Serapias cordigera’ is an orchid that is easily recogniseable by its heart-shaped lower lobe. 
The plant is 20 to 40 cm tall. Its stalk is clasped by leaves and is covered in purple strips. The flowerhead is quite short and dense and is made up of 3 to 10 flowers. 
This species prefers open or semi-open habitats. It is particularly found on land that has formerly been cultivated, former vineyards, or sparsely-wooded areas. 
If the vegetation is not regularly kept as the herb layer, this orchid disappears. 

An insect is an invertebrate animal, whose body is protected and maintained by an exoskeleton, is made up of three segments and which has three pairs of legs. 
Insects are the most common type of animal on our nature trail, where you can find: Lepidopterans (butterflies and moths), Orthopterans (such as bush-crickets), Coleopterans (such as ladybirds), and Hymenopterans (such as bees). 
Butterflies have a life cycle with four successive stages of metamorphosis. The egg is laid on one plant: the host plant. After a few days, the egg will hatch and a larva will appear: it’s a caterpillar. This will eat the leaves of its host plant and it will shed its skin four to six times. When the caterpillar has finished developing, it will go through a metamorphosis. For butterflies, this is called a chrysalis. The caterpillar surrounds itself with a hard case, which it has fixed to a support. Sometimes, this chrysalis is encased in a silk cocoon that it weaves with its saliva glands. Important transformations occur inside the chrysalis, some organs will wither away, such as digestive organs, and others will develop, such as legs, wings, antennae … When the chrysalis has finished its transformation, and if the weather is favorable, the chrysalis will split open and free the imago: the butterfly. 
Orthopterans have an incomplete metamorphosis: the immature insect that comes out of the egg is very similar to the adult insect, but it will undergo a series of moults where the wings will grow and the insect will become mature. 
Coleopterans, or beetles, undergo complete metamorphosis in four stages. The egg is laid on a substance needed for the life of the larva, (in the earth, on a plant, in compost …). After several days, the egg will hatch and a larva will appear. It will feed itself and undergo a series of moults. When it has finished its development, it will undergo a transformation, and when these are finished, and if the weather is favorable, the adult will appear. 
Hymenopterans, (ants, bees and wasps), also have a four-stage metamorphosis. The egg is laid. After a few days, the egg will hatch and a larva will appear. This is the larval stage. The larva will be fed by the workers, (if they are a social insect), or alone in its micro-habitat if it is not a social insect. When the larva is fully developed, it will undergo transformations, and when these are finished, the imago will appear. 

The River Courbet 
The stream of the Courbet is the reunion of three smaller streams near Pujaudran: the Sainte-Blaise, to the north, which starts in the municipal woodland at L’Isle Jourdain and collects water from there; the Cardayré, in the centre, which starts a few hundred metres north-east of Pujaudran; and the Lartus, to the south, which more or less follows the road deviation around Pujaudran. 
These three streams together form a river that is called le ruisseau de Sainte-Blaise in the Gers, becoming le Courbet, as it enters the Haute-Garonne. It passes through the districts of Pujaudran, Léguevin, Brax and Pibrac before ultimately converging with the Aussonelle at Colomiers. The catchment area covers 47 km2, stretching over 12 km, with an average slope of 5%. 
The Courbet collects and carries surface water run off, without other regular sources of inflows. This means that floods are more likely to occur in summer, during heavy storms, and they only last a few hours. 
Since 2011, all of the catchment wastewater has been fed into the Garonne by a collector system, and the Courbet is once again a clear river with good water quality. However, it is still prone to pollution and problems linked with storm water overflow, pollution caused by various pesticides, and water removed for irrigation purposes. 
Nonetheless, a fairly rich flora and fauna is found along this river. Among the ten or so fish species present, the Gudgeon is of particular note, as it is very sensitive to pollution. Its elongated body (15 cm for 30 grammes) is almost round in cross-section. Its tail fin is forked. It prefers places that are rich in organic matter, and shallow rivers. It likes to live in shoals. It rummages in the river bottom using the barbels either side of its mouth. It eats small molluscs, insect larvae, worms, zooplankton, crustaceans (gammarids – shrimp-like creatures, waterlice), as well as vegetable detritus. 
The Gudgeon spawns from May to June, in fast-flowing streams, among the stones and vegetation. At this period, the male Gudgeon’s head becomes rough, and is covered with small protrusions. The female lays about 2,000 eggs, which hatch after two or three weeks.