This species is mostly sedentary (del Hoyo et al.
1992), but moves seasonally within wetlands in response to changing water levels, showing movements in response to rains (Hancock et al.
2006a), which cause seasonal variation in habitat conditions (Tyler 2005). However the movements are in general poorly understood. It occurs year-round in some areas (such as Zambia) where it is not known to breed (Tyler 2005,
Kushlan and Hancock 2005). Occasional records from Malawi, Zimbabwe, Mozambique and South Africa indicate that the species has a tendency to vagrancy (del Hoyo et al.
1992, Kushlan and Hancock 2005).
Breeding appears to be irregular, but most often occurs during the months of March to June, coinciding with high flood-levels (Randall and Herremans 1994, Harrison et al.
1997, S. J. Tyler in litt
. 2007). It breeds in small colonies of 1-60 nests, and usually forages in small groups of 4-8 individuals (Hancock and Kushlan 1984), although it may forage solitarily or occasionally in larger aggregations of up to 60 individuals (Tyler 2005,
Kushlan and Hancock 2005). Habitat
It inhabits river floodplains, marshes, and temporary shallow wetlands, preferring areas where water levels are receding from their seasonal peak (Hancock, Elliott and Gillmor 1978, Hancock and Kushlan 1984, Kushlan and Hancock 2005). It tends to avoid open water (Kushlan and Hancock 2005), being most often found in areas where there is ample cover of short, emergent vegetation (Dowsett 1981, Martnez-Vilalta and Motis 1992) such as Cynodon dactylon
and Panicum repens
(Hancock et al.
2006a). The availability of this habitat is increased by fire and high grazing pressure, however there has so far been insufficient data to confirm important links between these factors and the species's abundance, although it has been observed to be more abundant on burnt floodplains, and it often occurs in association with Red Lechwe Kobus leche
(Hancock et al.
2006a). It forages in water less than 10cm in depth (Kushlan and Hancock 2005). Breeding
It breeds in temporary wetlands at the time of - or shortly after - maximum water levels (Kushlan and Hancock 2005). Its preferred breeding habitat is Phragmites
reedbed (Hancock et al.
2006a), but it will also nest on islands of vegetation such as water figs Ficus verruculosa
species (Hancock et al.
2006a, Reed 2006) and date (Tsaro) palms Phoenix reclinata
(Atkinson 2003, Hancock et al.
2006b) . Diet
When possible it feeds mainly on young fish (Dowsett 1981, Mathews and McQuaid 1983), especially cichlids (Hancock 2006c), but in temporary wetlands where fish do not occur, its diet consists of frogs, aquatic invertebrates (Hancock et al.
2006a, 2006c) and tadpoles (Hancock 2006c,
Kushlan and Hancock 2005, Mathews and McQuaid 1983). It locates prey by sight in clear, shallow water (Hancock et al.
2006a, 2006c). Additionally it will glean snails from lily pads and uses 'standing flycatching' to catch dragonflies and other insects (Mathews and McQuaid 1983, Kushlan and Hancock 2005
It forages diurnally, often in association with other heron and wader species (Kushlan and Hancock 2005). Breeding Site
The nest is a bowl lined with fine plant material (Hancock et al.
2006b), usually on a platform constructed from sticks, and the species shows high nest-site fidelity (Hancock et al.
2006a). Clutch-size has been recorded as 1-4 eggs, with a mean of 2.4 (n = 16) (Hancock et al.
2006a, 2006b), and the incubation period in one nest was recorded as 22-24 days (Hancock 2006a).