Redgannet: Costanera Sur Reserve, Buenos Aires, November 2012

My new-found companion, Morton and I, continued into Reserva Ecológica Costanera Sur. We had walked 2km along the promenade in Buenos Aires to reach the main gate and Visitors’ Centre (Google Earth ref; 34°36'59.71"S 58°21'18.78"W), noting 37 birds along the way. I want to treat the inside and outside of the park separately, so the post for our approach along the promenade can be seen below, or here. We took a very quick look at the Visitors’ Centre, noting a Saffron Finch as we did so, then turned left and headed northwest(-ish) on a path that ran parallel to the promenade.

The path was lined with the Tipuana Tipu tree that had also lined the promenade and are so common throughout the city. Morton spotted a Bran-coloured Flycatcher and while he was trying to point it out to me, a Small-billed Elainia too. Continuing on a theme he found a Streaked Flycatcher on the other side of the path.

What used to be lakes on the reserve had now silted up for the most part, so swathes of reeds reached out on both sides. Green-barred Woodpeckers were common and fed from the ground as well as in the trees that formed a covered avenue.

A streaky finch was bringing nesting material to line a nest cavity in one of the trees. Noticing the yellow shoulders we pencilled in Grassland Sparrow, but the streaks and the cavity-nesting must make it a Saffron Finch.

Towards the end of the straight, the path passes through a small area of Pampas Grass. Just beyond here, there is a secondary gate which recently appears to have become an official entrance and exit (at Google Earth ref; 34°35'56.65"S 58°21'44.70"W). To exit bear left (this is often a good place to find Gray-necked Wood Rail. We had seen one on the path just before reaching this spot), to continue, keep to the right.

We followed the path around to the right and headed towards the river. A Black-and-rufous Warbling-Finch sat for a moment. In a deep trench on the left we found a few Yellow-billed Teal and encountered this rather sizeable lizard.

Most of the common birds were living up to their reputation and were easy to see. Rufous Hornero, Rufous-bellied Thrush, Picazuro Pigeon and Eared Dove are all gimmes here. A brood of Chalk-browed Mockingbirds waited for their parents to bring food and were rewarded for their squealing.

The path now tracked along the bank of the Rio Plata and though there was not much to see out on the water, we both remarked on how many birds we were seeing inland on the reserve. Not just species, but lots of individuals too. Low in the grass by the path was a Grassland Yellow-Finch.

A few Brazilian Guinea-Pigs (Cuis) braved the edges of the path, but were quick to dive for cover as we approached.

Rufous-collared Sparrow and Black and Rufous Warbling Finches continued to be common along this stretch and Morton rounded out his mission to find lifer Flycatchers for me with a Yellow-browed Tyrant.

The day was wearing on and we took the quicker, diagonal route back to the Visitors’ Centre. The circuit had taken about 4 hours and had covered 4.5kms.We speeded up for the last section, unsure if there was a closing time at the gate, but a few birds were still able to slow us down. A Gilded Hummingbird sat nicely close to a viewing platform.

Birds seen; 37

Yellow-billed Teal 2, Neotropic Cormorant 3, Great Egret 3, Snowy Egret 1, Southern Caracara 3, Chimango Caracara 2, Gray-necked Wood-rail 1, Picazuro Pigeon 30, Eared Dove 20, Nanday Parakeet 5, Monk Parakeet 10, Gilded Hummingbird 1, Green-barred Woodpecker 8, Rufous Hornero 15, Small-billed Elaenia 3, Bran-colored Flycatcher 2, Yellow-browed Tyrant 1, Great Kiskadee 15, Streaked Flycatcher 2, Tropical Kingbird 6, Red-eyed Vireo 1, Brown-chested Martin 20, White-rumped Swallow 15, House Wren 8, Masked Gnatcatcher 3, Rufous-bellied Thrush 15, Creamy-bellied Thrush 4, Chalk-browed Mockingbird 10, White-lined Tanager 1, Golden-billed Saltator 5, Black-and-rufous Warbling-finch 5, Double-collared Seedeater 4, Saffron Finch 8, Grassland Yellow-finch 1, Rufous-collared Sparrow 5, Bay-winged Cowbird 5, Hooded Siskin 6.

The bird list from the promenade was, by coincidence, also 37 birds. The reserve gates do not open until 08.00, so the early birder can use his time effectively by scouring the Laguna de los Coipos, the long thin rectangle of reeds overlooked by the promenade, marked as no.6 on the map below.

Costanera Sur Ecological Reserve covers more than 800 acres on the bank of the Rio Plata in Buenos Aires. It started as a magnificent promenade where the good people of BA could come to bathe. It lost favour as the water quality in the river deteriorated and swimming fell out of fashion. Landfill and reclamation separated the promenade from the riverbank and subsequent silting gave Nature the chance to colonise and flourish. The reclaimed area became a protected reserve and was awarded Ramsar status in 2005.

The promenade still exists, though it is now over half a mile inland. It makes a fine walk on a warm afternoon, adjacent to the Ave Int. Hernan M. Geralt. For 2kms, the wide pavement looks down on a stretch of marsh and reeds. A few years ago rains would raise the level sufficiently for open water to attract many species of duck, but the water is much reduced now. Only tiny areas at the south-eastern end remain free from reeds but are likely to silt up altogether in the future.

Two gates allow visitors into the reserve. One can be found at each end of the promenade, but the one at the southeastern end (Google Earth ref; 34°36'59.71"S 58°21'18.78"W) is the main gate by the Visitors’ Centre. The gate at the ferry terminal end of the promenade (at Google Earth ref; 34°35'56.65"S 58°21'44.70"W) is more of a back door and does not always open as advertised. The opening hours are from 08.00 until 18.00 during the winter and 08.00 until 19.00 during the summer. The reserve is closed on Mondays and Public holidays.