Park Road 100 ends at the southern tip of the island in Isla Blanca, a Cameron County park with a daily entrance fee, campground, and the long granite jetty that flanks the north side of Brazos Santiago Pass. This is the island's seawatch. TPWD's entry lists northern gannet and magnificent frigatebird among the birds seen from the jetty, notes that Bonaparte's gulls are regular in winter, and records bridled tern and Cory's shearwater as rarities from the same vantage. The pass itself concentrates fish and therefore terns, pelicans, and gulls year-round, and the rock jetty attracts ruddy turnstones and other rock-loving shorebirds. The University of Texas Rio Grande Valley's Coastal Studies Laboratory is inside the park (chapter 09).
Bird gently
Stay on public paths, give resting and nesting birds room, keep voices low around blinds, and avoid crowding a bird for a photograph. Sightings are never guaranteed.