The Hadeda is a large (~76 cm long), grey-to-partly brown species of ibis, found throughout Sub-Saharan Africa in open grasslands, savanna and wetlands, as well as urban parks, school fields, green corridors and large gardens.
It has an extremely loud and distinctive "haa-haa-haa-de-dah" call -- hence the name. The call is often heard when the birds are flying or are startled, or when the birds communicate socially, for example early in the morning in residential suburbs.
Reference: Wikipedia