The crown jewel of Rio Grande Valley parks, Bentsen-Rio Grande Valley State Park well deserves its status as headquarters of the World Birding Center. Birders across the nation know Bentsen as a treasure trove of Valley specialties those birds found nowhere else in the United States but deepest South Texas and Mexican vagrants rare visitors from across the Rio Grande. The 760-acre Bentsen-RGV State Park, together with over 1,700 acres of adjoining federal refuge land, promises year-round nature adventures in the richest birding area north of the Mexican border. photos .. you can do 11 to 13 miles in some rough terrain