Occupying 57,191 acres on either side of the Rio Grande, this bird sanctuary is in a sense a manufactured habitat: Controlled flooding creates the marshes that draw the birds, which find food on farm plots dedicated to tasty grains. But this is really restoring a process that happened naturally before the Rio Grande was dammed.

The birds certainly have no objection. Arctic geese, sandhill cranes, bald eagles, and a whole variety of ducks happily settle in for the winter.

In the spring, migratory warblers and pelicans stop off on their way back to points north, while great blue herons make their spring nests here.

Summer is relatively quiet, as only the year-round species remain: hummingbirds, swallows, flycatchers, and the like.

Five miles inside the north border of the reserve, you pass the visitors center (7:30 a.m.–4 p.m. Mon.–Fri., 8 a.m.–4:30 p.m. Sat. and Sun.), where you can pick up maps and find out which birds have been spotted that day.

A bit farther south on Highway 1, a 12-mile paved car loop passes through all the marshlands and the grain fields; at certain points along the drive, you can get out and hike set trails, such as a quarter-mile boardwalk across a lagoon or a trail to the river. Some areas are open to mountain bikers.The loop drive opens when birdlife is at its best, one hour before sunrise; cars need to be out by an hour after dark.

With all its marshland, the bosque could just as well be called a mosquito sanctuary—slather on plenty of repellent before you start your drive.

The biggest event of the year is the arrival of the sandhill cranes—they were the inspiration for the refuge, as their population had dwindled to fewer than 20 in 1941, but now more than 15,000 of these graceful birds with six-foot wingspans winter over in the bosque.

They’re celebrated annually at the five-day Festival of the Cranes (www.friendsofthebosque.org/crane) in November, when birders gather to witness the mass morning liftoffs and evening fly-ins.