For birdwatchers the nearly 115,000-acre Aransas National Wildlife Refuge is the premier site on the Texas coast – especially to spot whooping cranes, of which only 15 once remained in the wild. Bird numbers peak during March and November migrations but are great throughout the year, and there's always the opportunity to spot ground-based animals like collared peccary, alligators, bobcats and many more. The visitor center should be your first stop, to the left on the main road into the park.
You can borrow binoculars here for free. A 40ft observation tower is a 5-mile walk or drive from the visitor center and overlooks much of the refuge. It has free telescopes, though during migration season their double purpose as a bird perch may keep you away. The Auto Tour Loop covers 16 miles, so allow two to four hours. Among several looped walks, the 1.4-mile Heron Flats Trail is less-visited, with some nice shady portions and beach frontage (though the second half of the loop is prone to flooding), while the 1-mile Dagger Point Trail hilltop section offers excellent views of the bay.
Bikes are a good way to explore the many hiking trails. Boats tour the estuaries from about mid-November to mid-April to spot whooping cranes, and this is easily the best way to get a good view of the rare birds.