Goliath Heron - Breeding

Breeding

Its breeding season coincides generally with the start of the rainy season, which is around November to March. In some areas, breeding is year around, with no discernable peak season. Breeding may not occur every year. Fairly adaptable in their nesting site selection, Goliath Herons generally prefer to nest on islands or islands of vegetation. The birds may abandon a nesting site if the island becomes attached to the mainland. Lakes or other large bodies of water usually hold colonies. They nest fairly low in variously sedge, reeds, bushes, trees or even on rocks or large tree stumps. The nesting dispersal seems highly variable as everything from a solitary pair (with no other Goliath nests anywhere near) to fairly large colonies have been observed, with no seeming local geographical preferences. Occasionally, they may join mixed-species colonies including other heron species, cormorants, darters, ibises and gulls. The breeding displays are not well known and may be subdued, due in part to breeding pairs possibly reunited year after year. The nests are large but often flimsy (depending on available vegetation around the nesting site), often measuring around 1 to 1.5 m (3.3 to 4.9 ft) in diameter.

Eggs are pale blue, averaging 72 mm (2.8 in) by 54 mm (2.1 in) and weighing around 108 g (3.8 oz). The clutch size can range from 2 to 5 (usually 3 or 4). Incubation lasts 24 to 30 days. Although they can sometimes replace clutches, often only around 25% of eggs succeed in hatching due to various environmental conditions or predation. The young are fed by regurgitation in the nest and, after a few weeks, can bill jab and practice defensive postures against each other. At around five weeks they leave the nest completely. The parents continue to tend to them for variously 40 to 80 days. Around 62% of fledgings who successfully leave the nest survive to adulthood. Locally, the White-tailed Eagle and the African Fish Eagle may be a predator at colonies. Due its size and formidable bill, the full-grown Goliath Heron may not have any regular avian predators. Despite their ponderous movements, Goliath Herons can think quickly and often take flight before mammalian carnivores (such as hyenas or jackals) can predate them.