A wilderness that grew on rubble: 350 hectares of lagoons, reedbeds and pampas grass behind the glass towers of Puerto Madero, with black-necked swans, screaming screamers, oven-building horneros and coypu, ten minutes' walk from the Casa Rosada.
In the 1970s the city dumped demolition rubble into the Río de la Plata behind the old port, meaning to build on it. The project was abandoned, the river silted in, and nature took over.
The marsh that grew over the rubble is now 350 hectares of lagoons, reedbeds and pampas grass, perhaps the best urban birding site in South America. Look for coscoroba and black-necked swans, southern screamers honking from the reeds, rufous horneros, Argentina's national bird, building their mud ovens, and hummingbirds in the flowering ceibos. Coypu and freshwater turtles bask on the banks.
Gravel tracks loop round the lagoons to the river wall, where the brown estuary stretches to the horizon. The reserve opens Tuesday to Sunday from 8am and closes on Mondays and after heavy rain. Go early with binoculars, then eat at the choripán carts along the Costanera outside the gate.
A flat loop; bring binoculars and take your time.
Cross from the docks to the southern entrance and pick up a map at the visitor centre.
The track skirts the first big lagoon, with coots, grebes, whistling ducks and swans in the open water.
Reach the old breakwater and the river, brown and endless, with Uruguay somewhere beyond the haze.
Return past the coypu lagoon and its reedbeds, listening for screamers and spinetails.
Leave by the north or south gate and eat at the grill carts along the Costanera.
Walk from San Telmo or Puerto Madero, about 15 minutes from Plaza de Mayo; or take a bus to the Costanera.
Open Tuesday to Sunday from 8am to early evening; check the city's website after storms.
Free guided walks and full-moon night walks run on some weekends: ask at the visitor centre.
Buenos Aires practical notes →Wikimedia Commons photographs are used under their licences.
