New Zealand's moa were exterminated by the hungry few

[Blind groper]

Piscator

Those ideas have been postulated. My personal view is that it is more likely that the giant moa were eated as carrion after death by the eagle rather than attacked and killed. The giant eagle reached a maximum mass of 12 to 15 kg, and the giant moa was a quarter tonne. Too much like David and Goliath.

On the other hand, there were 10 other, smaller species of moa, down to turkey size, and all flightless. They would have been easier prey. It is even possible that the evolutionary influence driving the big species to become a giant was to resist the giant eagle.

Other NZ native birds, like the kiwi, are nocturnal, probably to avoid predation by the giant eagle, so it is quite possible the moas were also nocturnal.

Anyway, I doubt they were totally dependent on moa. A dead seal is too easy, and provides good food. Pretty much all raptors are also carrion eaters when they can, and I see no reason the giant eagle should not also.

[mistermack]

The Moa might have been driven to extinction by humans eating their eggs, rather than eating the birds themselves.
Before humans came along, there was probably nothing that could break the shells of the eggs.

I have a feeling that the Moa eggs were bigger and thicker shelled than that.
And it looks like the bird is a trained performer. They taught her to roll over backwards, so they probably taught her to crack eggs as well.

One of those extinct huge eagles might have had the muscle to crack a moa egg I guess. But without the element of surprise, I doubt if it could take on an angry parent.
In any case, most predators don't hunt prey to extinction, unless they are newly arrived invaders.

[Hermit]

And it looks like the bird is a trained performer. They taught her to roll over backwards, so they probably taught her to crack eggs as well.

Black-breasted buzzards use stones to crack emu eggs in the wild.

Even birdbrains can be problem solvers.

[mistermack]

Black-breasted buzzards use stones to crack emu eggs in the wild.

Even birdbrains can be problem solvers.

Yeh, I know that's right, and it's pretty impressive. I think it was mentioned somewhere that it was nearly always abandoned eggs that didn't hatch that they would normally get a chance of.
I can't see it contributing to the extinction of the Moa though.
It would probably take longer in the wild, than in that demonstration, as that bird was probably coached, and supplied with ideal stones for the job.
In the wild, it takes a lot of experience for an animal to choose the right tool. You often see them using completely hopeless tools, when they are young, and learning the techniques.
Working out what is the best stone is actually quite a challenge, when you have a tiny brain.
But it is very impressive that they can do it.

[Blind groper]

If a New Zealand bird were to learn to crack moa eggs, it would be more likely to be a kea (mountain parrot), which David Attenborough described as the world's most intelligent bird. If the David says so, it gotta be right!

Keas are omnivores. The only parrots in the world to eat meat. They dig petrel chicks out of their burrows, and kill and eat them.

[Blind groper]

www.youtube.com/watch?v=bxoCuRuHlt8

Just in case you are interested, the youtube video referenced above shows the kea's antics and intelligence.

[mistermack]

The trick that sticks in my mind is where they perch on a sheep's back, and start eating it alive.
Nature in the raw. Literally.

[Blind groper]

That did not happen too often. A small number of occurences, which led to a vendetta against the kea.

I have happier memories of kea, with me hand feeding wild birds with cheese. I once camped just below the snow line in the South Island and got woken by a scrabbling noise. Got up to investigate and found several kea trying to pull out my tent pegs.

They have very powerful and sharp beaks, which serve as very effective tools.

Kea are known to tear off the rubber seals around car windscreens, and to use the iron roofs of huts as slides, apparently for sheer pleasure.

They are green on top, but scarlet under their wings. This may have been an adaptation to avoid being attacked by eagles. Flying low over tussock, they would be hard to see, but still able to carry out brilliant sexual displays by raising their wings, and 'flashing' their sexuality via the brilliant scarlet.

[JimC]

I tried flashing my sexuality once, but it got me in a spot of bother...