The park’s main conservation importance is that it holds three of the four Moroccan colonies of the northern bald ibis (Geronticus eremita). Together with the fourth site at nearby Tamri, it holds 95% of the world’s truly wild breeding birds of this endangered species.The ibis colonies and roost-sites are located on coastal cliffs within the National Park, and the coastal steppes and fields are used as feeding areas. The park has a nature trail at Oued Souss and a visitor centre at Oued Massa.
The Oued Massa holds water throughout the year and has breeding marbled ducks, a globally threatened species.[ It is the only known Moroccan breeding site for the glossy ibis. The two estuaries are important for migrants, especially waders and gulls. European spoonbilland Audouin’s gull winter in the park. Other notable breeding bird species are red-necked nightjar, thick-billed lark, Tristram’s warbler and Moussier’s redstart.
Souss-Massa also holds captive-breeding programmes for four threatened North African ungulates: scimitar oryx, addax, dama gazelle and dorcas gazelle, that are kept in separate enclosures within the park. The reintroduction of the North African ostrich – which is extinct north of the Sahara – is also underway.