This video from New Zealand is called Moa Footprints.
Mighty Moa Demise Detailed
June 15, 2005 — The moa, the biggest bird that ever lived, was hunted to extinction partly because of the extreme length of time it took the giant creature to reach reproductive maturity, scientists say.
The moa once thronged across New Zealand before being wiped out several hundred years ago by the Maori, the Polynesians who according to legend migrated to Aotearoa ("the land of the long white cloud") by canoe from the Cook Islands around seven centuries ago or longer.
The flightless, wingless bird, a cousin of the kiwi, stood up to 3.5 meters (11.5 feet) high and, at 250 kilos (550 pounds), was a plentiful source of meat.
But how did a small Maori population, armed only with close-range wooden weapons and traps, wipe out such a plentiful species in such a large country?
The answer, according to the new research, may be found in growth rings in the bones of these extinct giants.
These marks are common in many animal species and are caused by differing growth rates in changing seasons.
But bird species do not have these rings, as in most cases, their growth phase is confined to less than a year.
The moa, though, was the exception.
Examination of rings in stored bones suggest that the two moa species, luxuriating in the safety of New Zealand's unique ecosystem, may have taken several years to reach reproductive maturity and up to a decade to attain skeletal maturity.