the young, but survival rates in the former appear to be more consistent. Colonies typically consist of 5-15 nests, some of which are within 50 cm apart in tree colonies, but at different heights. One colony from a study on the llanos comprised as many as 40 nests. Colonial and solitary nesters also differ in the way they defend their nests. Colonial nesters are more aggressive than solitary nesters and physically attack intruders with bill jabbing. Contrarily, solitary nesters use a "lead-away" strategy, in which the nesting bird walks up behind the intruder with threatening bill clattering, and ceases to clatter its bill when the intruder moves away from the nest. Courtship and nesting displays Although colonial breeding is common amongst storks, the maguari stork differs in that courting takes place in congregations before established breeding pairs remove themselves to each of their nesting sites; whereas similar species such as the white stork and the oriental white stork court directly at the nest. 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. In the latter case however, it is unknown whether both mates enter the courtship assembly together or locate each other after each having migrated there separately. This stork shows unique nesting behaviours not observed in many other storks and that may reflect its adaptation to nesting on the ground. For example, it is one of a minority of stork species to perform a distinct Nest Covering Display to protect nestlings from potential predators. 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. Another nesting behaviour apparently unique to the maguari stork is the Mock Resting display. 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. This behaviour likely evolved as an adaptation to ground nesting in dense vegetation because the posture maintained by the nesting bird amongst the grass and reeds may render it difficult to see by the intruder;