Doñana holds one of the most species-rich birdwatching sites in Europe, full stop. The park's position at the junction of two flyways — the Atlantic route from northern Europe and the western Mediterranean route from central Europe — means it acts as a bottleneck for millions of migrating birds. In a single spring morning at the right location you might count twenty or thirty species without moving your feet: flamingoes, spoonbills, glossy ibis, avocets, black-winged stilts, marsh harriers quartering low over reeds, booted eagles circling overhead, red-knobbed coots and purple gallinules working the margins.
Year-round residents are impressive in their own right. The purple gallinule — an improbable-looking bird, violet-blue with a traffic-light red bill — is reliably visible at La Rocina. The little bittern hides in reedbeds along the same stretch. The Audouin's gull breeds on the coast. And the park holds a significant breeding population of the white-headed duck, a species that came close to extinction in western Europe and is still critically endangered globally. The viewing hides at La Rocina (near El Rocío) and El Acebuche give access without requiring a guided tour. Both have raised wooden platforms over the water with good westward light in the afternoon.