Behaviour This species is a sedentary resident and partial migrant, making irregular movements (Hockey et al. 2005)in response to changes in local water conditions, especially with the rising and falling of flood-levels (del Hoyo et al. 1992). The breeding season varies geographically, although most breeding peaks are associated with periods of rainfall (Johnsgard 1993) or flooding (del Hoyo et al. 1992). The species breeds in association with other waterbird species (del Hoyo et al. 1992, Nelson 2005), usually nesting in small numbers (1-5 pairs) amid much larger mixed-species colonies (Brown et al. 1982, Langrand 1990). It generally fishes singly (Brown et al. 1982, Langrand 1990, del Hoyo et al. 1992) or in small groups in shallow water by day (Brown et al. 1982, Langrand 1990), with peaks of activity in the early morning and late afternoon (Brown et al. 1982, Nelson 2005), occasionally also hunting cooperatively in loose associations with conspecifics or other species (Hockey et al. 2005, Nelson 2005). It commutes to foraging areas singly or in loose flocks (Hockey et al. 2005), and roosts nightly in large numbers (e.g. several thousands), often in mixed-species groups (Brown et al. 1982). During droughts the species may concentrate on permanent water-bodies, such as large rivers (del Hoyo et al. 1992). Habitat The species shows a preference for sheltered waters with fringing vegetation, emergent trees (del Hoyo et al. 1992, Nelson 2005) and gently sloping shores (Hockey et al. 2005), preferring to fish in shallow water c.2 m deep (Brown et al. 1982, Hockey et al. 2005, Nelson 2005), and within c.100 m of the shore (Nelson 2005). It is quick to colonise temporary flood-waters (del Hoyo et al. 1992), and will frequent most freshwater habitats except fast-flowing streams (Hockey et al. 2005), commonly roosting in Typha or Phragmites beds, or on partly submerged bushes or trees (Brown et al. 1982). Habitats include large and small slow-flowing rivers (Brown et al. 1982, del Hoyo et al. 1992, Nelson 2005), lagoons (del Hoyo et al. 1992, Hockey et al. 2005), ponds (Brown et al. 1982, del Hoyo et al. 1992), small farm dams, creeks, lakes (Nelson 2005), swamps (del Hoyo et al. 1992, Nelson 2005) and thickets of scrub or stands of trees within sedge-filled areas of water (Nelson 2005). It is occasionally observed on inland alkaline lakes (Brown et al. 1982, del Hoyo et al. 1992) and on freshwater wetlands along the coast (del Hoyo et al. 1992) (e.g. coastal lagoons) (Brown et al. 1982, Nelson 2005), and sometimes frequents rocky shores (Nelson 2005), inshore islands (Nelson 2005) with rocky outcrops and flats (Johnsgard 1993), mangrove swamps (Brown et al. 1982, del Hoyo et al. 1992, Nelson 2005), estuaries (Brown et al. 1982, del Hoyo et al. 1992, Hockey et al. 2005) and sheltered coastal waters (Hockey et al. 2005). Diet This species is a generalist, taking any slow-moving prey (Hockey et al. 2005). In estuaries, coastal lagoons and large inland lakes its diet is dominated by fish of up to 20 cm long, especially cichlids (Haplochromis, Pseudocrenilabrus and tilapia Sarotherodon) (Brown et al. 1982, del Hoyo et al. 1992), but at smaller water-bodies frogs, crustaceans, aquatic insects (Brown et al. 1982, del Hoyo et al. 1992), molluscs and occasionally small birds (Brown et al. 1982) are more important (Hockey et al. 2005). Breeding site The species nests in mixed-species colonies, with nests scattered throughout the group, often nearer water than the other species (Brown et al. 1982). The nest is a platform of twigs and other vegetation built 0.5-6 m above the ground (Brown et al. 1982), although the height of the nest is influenced by water-levels (it breeds higher in trees when water-levels are low, to reduce the risk of predation) (Hockey et al. 2005). Nesting sites include the forks of trees (often partly submerged, over water or on islands) (Hockey et al. 2005), reedbeds (Brown et al. 1982, del Hoyo et al. 1992, Hockey et al. 2005), sand (Nelson 2005) and tufts of vegetation on the ground (Brown et al. 1982), or cliffs and rocky outcrops on coastal islands (Hockey et al. 2005, Nelson 2005). Management information Three artificially constructed heronries in a man-made wetland at Blouvlei (Western Cape, South Africa) attracted a number of nesting pairs of this species which proceeded to breed successfully (Harrison et al. 2001). The heronries were erected in open water (the centre of a pond), and took the form of rectangular frameworks anchored by sunken corner posts, with natural poles and branches of dead wood arranged and secured within them to imitate natural thickets (Harrison et al. 2001). No decoy birds or nests were used (Harrison et al. 2001).