[4] The maguari stork was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[5] Gmelin's description was ultimately based on the "Maguari Brasiliensibus" that had been described and illustrated in 1648 by the German naturalist Georg Marcgrave in his book Historia Naturalis Brasiliae.

It soars at least a hundred metres above the ground with an outstretched neck and extended legs, intermittently beating its broad wings to gain momentum for long glides.

[13] After the chicks pass their third week of age, the black down develops olive streaks[21] and the only parts of the body that do not appear dark are the bright orange gular skin and a small patch of white down above and below the tail.

[22] This could arguably be advantageous because this stork breeds during the winter in the part of its range in the southern hemisphere, so that the chicks can be exposed to low environmental temperatures.

[10] The quality of these vocalisations is probably linked with the maguari stork's ground nesting habits and may be an adaptation to minimise attraction of predators’ attention.

[1] It is especially common and widespread in the Chaco of Argentina,[3] which appears to be a popular destination for flocks of about 30-40 migrant individuals from the southern hemisphere part of the range that come from the south in winter to seek warmer temperatures.

Its habitat largely comprises open lowland and shallow-water wetland such as tropical wet savannah grasslands, marshes, mudflats, and flooded fields.

[17] Numerous maguari stork assemblages have been observed in their habitat during the dry season, where they forage in low-level bodies of water where prey is concentrated.

[4] It feeds on fish, frogs, eels, earthworms, invertebrates, insect larvae, snakes, freshwater crabs, small mammals such as rats, and bird eggs.

More rarely, it may take smaller birds; as one case has shown where a large, intact rail was discovered in the gullet of an individual from Patagonia.

Its usual manner of hunting consists in walking slowly through wetlands with its bill close to the surface of the water, ready to seize any prey it comes into contact with.

[31] Notably numerous assemblages of foraging maguari storks have been sighted in the Brazilian municipality Quissama during the dry season in October, where they congregate around shallow pools in search of food.

[31] The maguari stork has been observed uplifting cowhides in dry fields in search of potential invertebrate prey underneath.

However, the proportions of these taxa differ between years depending on availability[13] and the food brought to the nest for the young consists predominantly of aquatic organisms.

Such differences in breeding and nesting habits have probably resulted from strong selection pressures that would have led this species to become adapted to survive in its open lowland wetland habitat that it originally invaded.

The nest always lies near to shallow water amongst tall grass and reeds,[10] since aquatic organisms form the bulk of the nestlings’ diet.

[13] Common species used in nest fabrication include the reed Cyperus giganteus and the marsh grass Zizianopsis bonariensis,[10] alongside other aquatic plants in the families Polygonaceae and Solinaceae.

[13] Ground nests found in the southern parts of the maguari stork's range are one-meter-high (3.3 ft) conical structures measuring 1.5–2.5 m in basal diameter, tapering to a flat platform of 1–1.5 m at the top.

[10] In the Venezuelan llanos, the maguari stork is also found to nest in low, thick-trunked trees including Ficus pertusa and Randia venezuelansis.

[10] These nuptial congregations in the maguari stork occur at freshwater marshes that have already been flooded with rainwater to a depth of about 20 cm and are the venue either for the formation of new pair-bonds in young individuals or for the reunion of mates from previous years.

[2][11] During this display, the nesting stork droops its wings along its sides with a strongly cocked tail and erect feathers on the head and neck; accompanied by a clattering of the bill that is pointed almost vertically downward.

[2] Here, during the presence of an intruder near the nest, the individual stands motionless with its back strongly arched, neck retracted, and wings and bill folded almost vertically downward.

[11] They crouch forward, partially spread their wings and erect the black feathers on their head, neck and back; followed by a shrill, rasping scream and an attempt to grab a persistent intruder with their bill.

[11] In many other stork species, akinesia lasts throughout much of the nestlings’ early life, and the constantly white plumage makes them appear as eggs to potential chick predators.

[21] Natural enemies of this stork include boa constrictors[21] and crested caracaras (Polyborus plancus),[32] both of which eat this species’ eggs.

[2] The maguari stork is potentially threatened in the Pantanal, which as well as being subject to considerable land reclamation for agriculture, has hosted increased operation of hydroelectric dams, especially in the Parana river basin.

Conversely, during the wet season, dams can lead to extensive flooding downstream caused by the release of a large volume of water at once that renders the storks’ usual foraging grounds too deep for them to stand in.

This should be a new target of conservationists, and a clearer overview of this stork's world status could be aided by carrying out numerous aerial surveys of nesting areas.

[27] Despite its relatively unthreatened overall status, the maguari stork should deserve closer global population monitoring to better safeguard it from future potential large-scale declines across its entire range.