Despite the variety of waterfowls present nowadays, the three major lagoons in the reserve were once dry grasslands for years because of a drought. In 2013, a system of pumps was constructed to pump the water from Rio de La Plata, which led to the return of more than 20 species of birds within the same year.
Standing besides the lagoons, it is possible to see different waterfowls such as Rosy-billed Pochard, Silver Teal, Brazilian Teal, Yellow-billed Teal, just to name a few. These are species that can be seen in all the lagoons. However, the most spectacular ducks would be the two kinds of whistling-ducks: Fulvous Whistling-Duck and White-faced Whistling-Duck.
One can also find several kinds of herons and egrets perching in the lagoons. The most common one is the Great Egret, which usually flies overhead. The Snowy Egret differs from the Great Egret not only in its bill color, but it is also conspicuously smaller and more active. If you pay some attention, you will definitely find the solitary and static Cocoi Heron, which closely resembles the Grey Heron in the Old World.
However, if I’m asked to name the bird with greatest panache, Rufescent Tiger-Heron will definitely be the strongest candidate. Its color pattern always reminds me of the Chinese Pond Heron, which is distributed mainly in Asia. But its color is so much more soothing and picturesque compared to any other species.
There is also the need of getting to know some species that do not belong to our familiar categories of birds: Southern Screamer (Chauna torquata), Limpkin (Aramus guarauna), and Wattled Jacana (Jacana jacana). They can all be found in the reserve. All of these birds have unique characteristics that make them one of the few species in their corresponding family.
Southern Screamer is one of the three species in its family Anhimidae. It is mostly close to ducks. Walking around the lagoons, sometimes you can hear the loud scream coming from a flock of them. Limpkin is the only member of family Aramidae, which is skeletally close to the cranes. Wattled Jacanas are one of the eight members of its family. They are usually seen walking in floating vegetation with their huge feet. They also showcase their bright yellow underwing in flight. The most intriguing thing about Wattled Jacanas is that they adopt a polyandrous mating system, in which males take care of the fledglings and females mate with multiple males. To put things into perspective, only about 1% of the birds are polyandrous.
Rails are also common inhabitants of the reserve. It is possible to find species including Common Gallinule and Spot-flanked Gallinule. In addition, there are three species of coots in the reserve, including the Red-gartered Coot, White-winged Coot, and Red-fronted Coot. The major field mark to distinguish them is the color of their bill and frontal shield.
The most amazing rails would be the Giant Wood-Rail, the Gray-cowled Wood-Rail, and the Plumbeous Rail. They are probably the shyest birds in the reserve that often run through bushes beside the lagoons. In order to spot them, you have to wait patiently in one place or pay close attention to the movement in the bushed when walking. If you are lucky enough, you’ll see them traversing the trail quickly.
There are much more genera of birds that have not yet been discussed: grebes, gulls, ibises, etc. It is truly overwhelming to even attempt to introduce all the birds in Reserva Ecológica Costanera Sur, especially when it has more than 300 species of birds on record. And remember, part of the success can be attributed to the feat of human engineering. When the water from Río de La Plata was pumped into the lagoons, we’ve seen the return of these waterfowls. It proves that by creating an appropriate habitat, we can recover and preserve biodiversity in one place in a short period of time.
[To be continued…]
The Green Rocks 