The coastal lagoons of the Puerto Vallarta region lie astride the Pacific flyway, one of the Americas’ major north–south paths for migrating waterfowl. Many of the familiar American and Canadian species, including pintail, gadwall, baldpate, shoveler, redhead, and scaup, arrive October–January, when their numbers will have swollen into the millions. They settle near food and cover—even at the borders of cornfields, to the frustration of farmers.

Besides the migrants, swarms of resident species—herons and egrets (garzas), cormorant-like anhingas, lily-walkers (jacanas), and hundreds more—stalk, nest, and preen in the same lagoons.

Few spots are better for observing seabirds than the beaches of the Puerto Vallarta region. Brown pelicans and black-and-white frigate birds are among the prime actors. When a flock of pelicans spots a school of their favorite fish, they go about their routine deliberately. Singly or in pairs, they circle and plummet into the waves to come up, more often than not, with fish in their gullets. Each bird then bobs and floats over the swells for a minute or two, seeming to wait for its dozen or so fellow pelicans to take their turns. This continues until they’ve bagged a dinner of 10–15 fish apiece.

Frigate birds, the scavengers par excellence of the Puerto Vallarta region, often profit by the labor of the teams of fishermen who haul in nets of fish on village beaches. After the fishermen auction off the choice morsels of perch, tuna, red snapper, octopus, or shrimp to merchants, and the local villagers have scavenged everything else edible, the motley residue of small fish, sea snakes, skates, squid, slugs, and sharks is thrown to a screeching flock of frigate birds.

The sprawling, wild mangrove wetland near San Blas, 100 miles north of Puerto Vallarta, nurtures a trove of wildlife, especially birds, ripe for viewing on foot near the town, or by guided boat tours.