Valladolid Natural Spaces
Riberas de Castronuño
The Riberas de Castronuño is a natural space situated in
the Midwestern region of the province of Valladolid, and covers
the stretch of the river Duero between the localities of Tordesillas
and Castronuño. The latter also contains the Embalse de
San José (reservoir). The Riberas de Castronuño
constitutes a classic marsh ecosystem, noted for its importance
as a nesting and hibernating zone for many water birds. An interesting
riverbank forest, formed mainly of black poplars, willows, white
poplars, ash trees and hawthorns, accompanies the river along
its course down the sedimentary plain.
As well as adding beauty to the plain landscape, this rocky area
provides protection and refuge for a great number of birds, most
notably, significant colonies of grey heron, night heron and little
egret.
Castronuño is also a hibernating zone for a great number of mallards, shovelers, pochards and cormorants. Upstream from Castronuño, we find the interesting town of Tordesillas, site of many convents, churches, palaces and hospitals. The town gives it name to the famous treaty signed there at the end of the 15th century, by which the kingdoms of Castille and Portugal divided up dominion of the whole world .