by Bruce Batt, Ph.D.
The west coast of Mexico provides vital wintering habitat for North American waterfowl. Its importance grew in the middle of the last century as the million-acre Colorado River Delta was destroyed with the almost complete diversion of its water for agricultural, recreational, and domestic uses in the western United States. The Central Valley of California is now the most critical wintering area for Pacific Flyway waterfowl. Biologists consider habitat conditions there to be better now than they have been in the past 20 years. Farmers now flood more than 300,000 acres of rice stubble that provides excellent habitat for more than 5 million waterfowl.
All is not secure, though, in the Central Valley, as current rice-farming practices are not certain to continue for the long term. Drought could also easily eliminate for one or more winters much of the water needed for flooding rice fields, refuges, and wildlife management areas in California. Thus, the wetlands of Mexico’s west coast are a critical safety valve for Pacific Flyway waterfowl.
Most of the important wetland habitats are in three states: Sonora, Sinaloa, and Nyarit. These wetlands—predominantly coastal lagoons, bahías, and estuaries—provide a variety of habitats grading from brackish to freshwater. Until about 15 years ago, agriculture also provided significant food resources for waterfowl, as farmers planted 300,000 acres of irrigated rice in Sonora and Sinaloa. But the rice is gone now. World markets have lowered the price so much that growing rice is no longer economically feasible in Mexico. With the loss of those 300,000 acres of rice, the remaining wetland habitats are even more important to wintering waterfowl.