Lake Calderón Chica and Ballestera Nature Reserve

One of the town’s protected areas of greatest wealth shines in its own light, the Endorheic Area. Each year, its beautiful and shallow lakes are visited by species of birds that rest in Osuna on their migratory route.

The lakes of Ballestera and Calderón Chica form the Nature Reserve of the Lantejuela Endorheic Complex, located in the north west of the municipality of Osuna. The area occupied by the Nature Reserve falls within the boundary between the Baetic Depression and the Sub-baetic units, where there was once a large endorheic area which spread across the Osuna and Ecija countryside.

Lake Calderón Chica

The high salinity which characterises its waters is one of the most striking values of the endorheic complex since it causes the colonisation of highly specialised species, of very restricted distribution, such as the aquatic macrophyte, Althenia Orientalis. A lake of scarce vegetation, formed by some isolated tamarisk stems together with some specimens of bulrushes, salicornias and other species adapted to conditions of high salinity.

Lake Ballestera

This lake also has severely degraded vegetation, preserving areas of reedbed and isolated tamarisk stems. Despite this, this lake is exceptionally important because of the presence of two aquatic plant species, of the Althenia genus, with a very limited supply in Andalusia. It is also characterised for being one of the protected areas of greatest environmental wealth and for its shallow waters.

The importance of the fauna of this complex lies in the abundance of aquatic birds, as the area is usually visited by numerous aquatic birds in migration. In particular, waterfowl come to this area as a place to rest and reproduce: mallards, northern shovelers, Eurasian wigeons, common shelduck, flamingos and, occasionally, greylag geese.

Its hundred-year-old holm oaks are the ideal place for large birds of prey, such as the Red Kite, Bonelli’s eagle, Marsh harrier, Common buzzard or Montagu’s harrier. Birds which, undoubtedly, offer us beautiful scenes and will make us fall in love with their spectacular flights.

Of all of the actions carried out, we can highlight the restoration of a significant and interesting pillar, the construction of 3 ornithological observatories, the installation of a picnic area, the reforestation of more than 3000 plants and the census and study of these lakes.