A deep estuary with some remnant brackish marshes, extensive mudflats and sandbanks. There is a small rocky islet at the mouth of the estuary and a large coastal cliff in the west of the area.
This is an important site for passage and wintering waders and Platalea leucorodia and resident seabirds.
Pressure/threats to key biodiversity
The main threats include disturbance from tourists and intense shellfish gathering and trawling. The bottom of the estuary has been damaged by dredging. There is a management plan for the Biosphere Reserve. Hunting is forbidden.
National None International Partial945 ha of IBA covered by Ramsar Site (Ría de Mundaka-Guernika, 945 ha). 1,020 ha of IBA covered by Biosphere Reserve (Urdaibai, 23,000 ha). 1,020 ha of IBA covered by Special Protection Area (Urdaibai, 23,000 ha).
BirdLife International (2020) Important Bird Areas factsheet: Urdaibai - Matxitxako. Downloaded from
http://www.birdlife.org on 29/11/2020.