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. Nesting habits Unlike other stork species, this stork is commonly found to nest on the ground, whereas many other stork species habitually nest at higher elevation. The nest always lies near to shallow water amongst tall grass and reeds, since aquatic organisms form the bulk of the nestlings’ diet. The maguari stork's nest is also unusual in extensively comprising grass and reeds. Common species used in nest fabrication include the reed Cyperus giganteus and the marsh grass Zizianopsis bonariensis, alongside other aquatic plants in the families Polygonaceae and Solinaceae. 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. The nest rises up to two feet above the surface of the water and its location is largely treeless. Hence overall, the maguari stork's nest seems to more closely resemble that of cranes and screamers such as the southern screamer Chauna torquata than that of other stork species. In the Venezuelan llanos, the maguari stork is also found to nest in low, thick-trunked trees including Ficus pertusa and Randia venezuelansis. These nests comprise sticks that are usually less than a metre long and less than 2 cm in diameter, and often from the palm species Copernicia tectorum. Nevertheless, the species does not seem to naturally perch in trees because unlike its sympatric heterospecifics such as the jabiru, it cannot stand on its hallux. Therefore, it probably only nests opportunistically above the ground. The same nest may be used by a pair in successive years, sometimes for as long as seven years. However, ground nests composed of herbaceous plants usually disintegrate after a year, whereupon the same breeding pair returns to the nest site to rebuild the nest. Both partners participate in building and lining the nest, which continues throughout incubation and brooding. Nest lining usually begins when the base is about a metre wide, and lining material largely consists of wet grass that dries and hardens in the intense sun. The maguari stork is primarily a colonial nester, although it also less frequently nests solitarily. Solitary nests are found to be less successful than colonial nests in terms of survival of