Grus americana

Aransas NWR, near Rockport, TX

Blue crabs make up 80% - 90% of a Whooping Crane's diet. The salt marshes near Aransas NWR provide excellent habitat for blue crabs if the water salinity is the right degree of brackish (5 - 15 parts per thousand; open ocean salinity is 32 parts per thousand). Most of the fresh water that flows into San Antonio Bay comes from the Guadalupe and San Antonio rivers. If there is insufficient flow of fresh water from these rivers, the salinity greatly increases and blue crabs cannot survive. Thus, the fate of Whooping Cranes is strongly tied to the availability of fresh water to the San Antonio estuary.