Habitat and Ecology
Habitat and Ecology
Behaviour This species makes little known7 dispersive movements1, 3 related to water conditions1, 2. It is locally nomadic in southern Africa in response to changing wetland conditions6, and western African populations make northward movements into sub-Saharan steppe during the wet season, returning southwards in the dry season1, 2, 4. The species breeds all year round, although most start late in the wet season1, 3, 4. It is gregarious both during breeding and non-breeding5, nesting in small groups or larger loose colonies of between 20 and 500 pairs1, 2, 7 (often alongside other species3, 5). It roosts nocturnally in groups4, but is more of a solitary feeder, preferring to fish singly or in small loose groups of less than 30 individuals3, 4, 5. It is chiefly diurnally active, especially during the morning and evening, although it may also fish on moonlit nights2, 5. Habitat The species inhabits a wide range of aquatic habitats, but prefers to feed in quiet backwaters and weed-grown lagoons1 where there is shallow water and emergent vegetation5, generally avoiding steep, vegetated lake margins3. It shows a preference for freshwater lakes, swamps, large slow-flowing rivers, and seasonal pools1, 2, 3, 4, 5, but also frequents reservoirs2, 4, seasonally flooded land3 and flood-plains near river mouths7. It may occur on alkaline and saline lakes and lagoons2, 3, 4, 5, and can sometimes be found along the coast in bays1 and estuaries2, 3, 5 (although seldom on open seashore)2, 3. The species tends to roost and breed in trees (e.g. mangroves), but will also roost on sandy islands, cliffs, coral reefs and sand-dunes1. Nesting trees are often killed by repeated nesting, which forces breeding colonies to move (although birds will usually not move far)1, 2. Diet The diet of this species consists entirely of fish (of any size up to 450 g, although usually in the range of 80-290 g)3, with cichlids (especially Haplochromis and Tilapia) being preferred1, 2, 3, 4. Breeding site The species nests colonially in trees, reeds or low bushes along waterfronts1, 2, 3 as well as (less often) on the ground on sandy islands and in mangroves1, 3. The nest is small and constructed of sticks1, and may be situated at elevations of 10-50 m above the ground4. A single tree may contain many nests3 that can be very close together (often touching)7, and a single pair will refurbish and re-use the same nest from year to year if it has not collapsed3.
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