Largest organisms were related to the ostrich. They exceeded in height and . The last of the elephant birds became extinct about 300 years ago. Of almost exactly the same upper proportions as the largest elephant birds was "Dromornis stirtoni" of Australia, part of a 26,000-year-old group called mihirungs of the family Dromornithidae. The largest carnivorous bird was "Brontornis", an extinct flightless bird from South America which reached a weight of and a height of about . The tallest carnivorous bird was "Kelenken", which could reach 3 to 3.2 meters in height and 220 to 250 kilograms. The tallest bird ever was
Bird care after fledging varies; albatross chicks leave the nest on their own and receive no further help, while other species continue some supplementary feeding after fledging. Chicks may also follow their parents during their first migration. Brood parasitism, in which an egg-layer leaves her eggs with another individual's brood, is more common among birds than any other type of organism. After a parasitic bird lays her eggs in another bird's nest, they are often accepted and raised by the host at the expense of the host's own brood. Brood parasites may be either "obligate brood parasites", which must lay their